Internet DRAFT - draft-schanzen-gns

draft-schanzen-gns







Independent Stream                                       M. Schanzenbach
Internet-Draft                                          Fraunhofer AISEC
Intended status: Informational                               C. Grothoff
Expires: 7 January 2024                            Berner Fachhochschule
                                                                  B. Fix
                                                             GNUnet e.V.
                                                             6 July 2023


                          The GNU Name System
                         draft-schanzen-gns-28

Abstract

   This document contains the GNU Name System (GNS) technical
   specification.  GNS is a decentralized and censorship-resistant
   domain name resolution protocol that provides a privacy-enhancing
   alternative to the Domain Name System (DNS) protocols.

   This document defines the normative wire format of resource records,
   resolution processes, cryptographic routines and security
   considerations for use by implementers.

   This specification was developed outside the IETF and does not have
   IETF consensus.  It is published here to inform readers about the
   function of GNS, guide future GNS implementations, and ensure
   interoperability among implementations including with the pre-
   existing GNUnet implementation.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 7 January 2024.






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Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Notation . . . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     3.1.  Names and Zones . . . . . . . . . . . . . . . . . . . . .   7
     3.2.  Publishing Binding Information  . . . . . . . . . . . . .   8
     3.3.  Resolving Names . . . . . . . . . . . . . . . . . . . . .   9
   4.  Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . .  10
     4.1.  Zone Top-Level Domain . . . . . . . . . . . . . . . . . .  12
     4.2.  Zone Revocation . . . . . . . . . . . . . . . . . . . . .  13
   5.  Resource Records  . . . . . . . . . . . . . . . . . . . . . .  17
     5.1.  Zone Delegation Records . . . . . . . . . . . . . . . . .  19
       5.1.1.  PKEY  . . . . . . . . . . . . . . . . . . . . . . . .  20
       5.1.2.  EDKEY . . . . . . . . . . . . . . . . . . . . . . . .  23
     5.2.  Redirection Records . . . . . . . . . . . . . . . . . . .  27
       5.2.1.  REDIRECT  . . . . . . . . . . . . . . . . . . . . . .  27
       5.2.2.  GNS2DNS . . . . . . . . . . . . . . . . . . . . . . .  27
     5.3.  Auxiliary Records . . . . . . . . . . . . . . . . . . . .  28
       5.3.1.  LEHO  . . . . . . . . . . . . . . . . . . . . . . . .  28
       5.3.2.  NICK  . . . . . . . . . . . . . . . . . . . . . . . .  29
       5.3.3.  BOX . . . . . . . . . . . . . . . . . . . . . . . . .  30
   6.  Record Encoding for Remote Storage  . . . . . . . . . . . . .  31
     6.1.  The Storage Key . . . . . . . . . . . . . . . . . . . . .  33
     6.2.  Plaintext Record Data (RDATA) . . . . . . . . . . . . . .  34
     6.3.  The Resource Records Block  . . . . . . . . . . . . . . .  35
   7.  Name Resolution . . . . . . . . . . . . . . . . . . . . . . .  37
     7.1.  Start Zones . . . . . . . . . . . . . . . . . . . . . . .  38
     7.2.  Recursion . . . . . . . . . . . . . . . . . . . . . . . .  39
     7.3.  Record Processing . . . . . . . . . . . . . . . . . . . .  40
       7.3.1.  REDIRECT  . . . . . . . . . . . . . . . . . . . . . .  41
       7.3.2.  GNS2DNS . . . . . . . . . . . . . . . . . . . . . . .  41
       7.3.3.  BOX . . . . . . . . . . . . . . . . . . . . . . . . .  42



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       7.3.4.  Zone Delegation Records . . . . . . . . . . . . . . .  43
       7.3.5.  NICK  . . . . . . . . . . . . . . . . . . . . . . . .  43
   8.  Internationalization and Character Encoding . . . . . . . . .  44
   9.  Security and Privacy Considerations . . . . . . . . . . . . .  44
     9.1.  Availability  . . . . . . . . . . . . . . . . . . . . . .  44
     9.2.  Agility . . . . . . . . . . . . . . . . . . . . . . . . .  45
     9.3.  Cryptography  . . . . . . . . . . . . . . . . . . . . . .  45
     9.4.  Abuse Mitigation  . . . . . . . . . . . . . . . . . . . .  46
     9.5.  Zone Management . . . . . . . . . . . . . . . . . . . . .  47
     9.6.  DHTs as Remote Storage  . . . . . . . . . . . . . . . . .  48
     9.7.  Revocations . . . . . . . . . . . . . . . . . . . . . . .  48
     9.8.  Zone Privacy  . . . . . . . . . . . . . . . . . . . . . .  49
     9.9.  Zone Governance . . . . . . . . . . . . . . . . . . . . .  49
     9.10. Namespace Ambiguity . . . . . . . . . . . . . . . . . . .  50
   10. GANA Considerations . . . . . . . . . . . . . . . . . . . . .  51
     10.1.  GNS Record Types Registry  . . . . . . . . . . . . . . .  51
     10.2.  .alt Subdomains Registry . . . . . . . . . . . . . . . .  52
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  53
   12. Implementation and Deployment Status  . . . . . . . . . . . .  53
   13. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  54
   14. Normative References  . . . . . . . . . . . . . . . . . . . .  54
   15. Informative References  . . . . . . . . . . . . . . . . . . .  57
   Appendix A.  Usage and Migration  . . . . . . . . . . . . . . . .  59
     A.1.  Zone Dissemination  . . . . . . . . . . . . . . . . . . .  59
     A.2.  Start Zone Configuration  . . . . . . . . . . . . . . . .  60
     A.3.  Globally Unique Names and the Web . . . . . . . . . . . .  61
     A.4.  Migration Paths . . . . . . . . . . . . . . . . . . . . .  62
   Appendix B.  Example flows  . . . . . . . . . . . . . . . . . . .  63
     B.1.  AAAA Example Resolution . . . . . . . . . . . . . . . . .  63
     B.2.  REDIRECT Example Resolution . . . . . . . . . . . . . . .  64
     B.3.  GNS2DNS Example Resolution  . . . . . . . . . . . . . . .  65
   Appendix C.  Base32GNS  . . . . . . . . . . . . . . . . . . . . .  66
   Appendix D.  Test Vectors . . . . . . . . . . . . . . . . . . . .  67
     D.1.  Base32GNS en-/decoding  . . . . . . . . . . . . . . . . .  67
     D.2.  Record sets . . . . . . . . . . . . . . . . . . . . . . .  68
     D.3.  Zone revocation . . . . . . . . . . . . . . . . . . . . .  81
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  84

1.  Introduction

   This specification describes the GNU Name System (GNS), a censorship-
   resistant, privacy-preserving and decentralized domain name
   resolution protocol.  GNS cryptographically secures the binding of
   names to arbitrary tokens, enabling it to double in some respects as
   an alternative to some of today's public key infrastructures.






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   In the terminology of the Domain Name System (DNS) [RFC1035], GNS
   roughly follows the idea of a local root zone deployment (see
   [RFC8806]), with the difference that the design encourages
   alternative roots and does not expect all deployments to use the same
   or any specific root zone.  In the GNS reference implementation,
   users can autonomously and freely delegate control of names to zones
   through their local configurations.  GNS expects each user to be in
   control of their setup.  By following Section 9.10 guidelines, users
   should manage to avoid any confusion as to how names are resolved.

   Name resolution and zone dissemination is based on the principle of a
   petname system where users can assign local names to zones.  The GNS
   has its roots in ideas from the Simple Distributed Security
   Infrastructure [SDSI], enabling the decentralized mapping of secure
   identifiers to memorable names.  A first academic description of the
   cryptographic ideas behind GNS can be found in [GNS].

   This document defines the normative wire format of resource records,
   resolution processes, cryptographic routines and security
   considerations for use by implementers.

   This specification was developed outside the IETF and does not have
   IETF consensus.  It is published here to guide implementers of GNS
   and to ensure interoperability among implementations.

1.1.  Requirements Notation

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Terminology

   Apex Label  This type of label is used to publish resource records in
      a zone that can be resolved without providing a specific label.
      It is the GNS method to provide what is the "zone apex" in DNS
      [RFC4033].  The apex label is represented using the character
      U+0040 ("@" without the quotes).

   Application  A component which uses a GNS implementation to resolve
      names into records and processes its contents.

   Blinded Zone Key  Key derived from a zone key and a label.  The zone
      key and any blinded zone key derived from it are unlinkable
      without knowledge of the specific label used for the derivation.




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   Extension Label  This type of label is used to refer to the
      authoritative zone that the record is in.  The primary use for the
      extension label is in redirections where the redirection target is
      defined relative to the authoritative zone of the redirection
      record (see Section 5.2).  The extension label is represented
      using the character U+002B ("+" without the quotes).

   Label Separator  Labels in a name are separated using the label
      separator U+002E ("." without the quotes).  In GNS, with the
      exceptions of zone Top-Level Domains (see below) and boxed records
      (see Section 5.3.3), every label separator in a name indicates
      delegation to another zone.

   Label  A GNS label is a label as defined in [RFC8499].  Labels are
      UTF-8 strings in Unicode Normalization Form C (NFC)
      [Unicode-UAX15].  The apex label and the extension label have
      special purposes in the resolution protocol which are defined in
      the rest of the document.  Zone administrators MAY disallow
      certain labels that might be easily confused with other labels
      through registration policies (see also Section 9.4).

   Name  A name in GNS is a domain name as defined in [RFC8499]: Names
      are UTF-8 [RFC3629] strings consisting of an ordered list of
      labels concatenated with a label separator.  Names are resolved
      starting from the rightmost label.  GNS does not impose length
      restrictions on names or labels.  However, applications MAY ensure
      that name and label lengths are compatible with DNS and in
      particular IDNA [RFC5890].  In the spirit of [RFC5895],
      applications MAY preprocess names and labels to ensure
      compatibility with DNS or support specific user expectations, for
      example according to [Unicode-UTS46].  A GNS name may be
      indistinguishable from a DNS name and care must be taken by
      applications and implementors when handling GNS names (see
      Section 9.10).  In order to avoid misinterpretation of example
      domains with (reserved) DNS domains this draft uses the suffix
      ".gns.alt" in examples which is also registered in the GANA ".alt
      Subdomains" registry [GANA] (see also [I-D.ietf-dnsop-alt-tld]).

   Resolver  The component of a GNS implementation which provides the
      recursive name resolution logic defined in Section 7.

   Resource Record  A GNS resource record is the information associated
      with a label in a GNS zone.  A GNS resource record contains
      information as defined by its resource record type.

   Start Zone  In order to resolve any given GNS name an initial start





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      zone must be determined for this name.  The start zone can be
      explicitly defined as part of the name using a zone Top-Level
      Domain (zTLD).  Otherwise, it is determined through a local
      suffix-to-zone mapping (see Section 7.1).

   Top-Level Domain  The rightmost part of a GNS name is a GNS Top-Level
      Domain (TLD).  A GNS TLD can consist of one or more labels.
      Unlike DNS Top-Level Domains (defined in [RFC8499]), GNS does not
      expect all users to use the same global root zone.  Instead, with
      the exception of Zone Top-Level Domains (see Section 4.1), GNS
      TLDs are typically part of the configuration of the local resolver
      (see Section 7.1), and might thus not be globally unique.

   Zone  A GNS zone contains authoritative information (resource
      records).  A zone is uniquely identified by its zone key.  Unlike
      DNS zones, a GNS zone does not need to have a SOA record under the
      apex label.

   Zone Key  A key which uniquely identifies a zone.  It is usually a
      public key of an asymmetric key pair.  However, the established
      technical term "public key" is misleading, as in GNS a zone key
      may be a shared secret that should not be disclosed to
      unauthorized parties.

   Zone Key Derivation Function  The zone key derivation function (ZKDF)
      blinds a zone key using a label.

   Zone Master  The component of a GNS implementation which provides
      local zone management and publication as defined in Section 6.

   Zone Owner  The holder of the secret (typically a private key) that
      (together with a label and a value to sign) allows the creation of
      zone signatures that can be validated against the respective
      blinded zone key.

   Zone Top-Level Domain  A GNS Zone Top-Level Domain (zTLD) is a
      sequence of GNS labels at the end of a GNS name which encodes a
      zone type and zone key of a zone (see Section 4.1).  Due to the
      statistical uniqueness of zone keys, zTLDs are also globally
      unique.  A zTLD label sequence can only be distinguished from
      ordinary TLD label sequences by attempting to decode the labels
      into a zone type and zone key.

   Zone Type  The type of a GNS zone determines the cipher system and
      binary encoding format of the zone key, blinded zone keys, and
      cryptographic signatures.





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3.  Overview

   GNS exhibits the three properties that are commonly used to describe
   a petname system:

   1.  Global names through the concept of zone top-level domains
       (zTLDs): As zones can be uniquely identified by their zone key
       and are statistically unique, zTLDs are globally unique mappings
       to zones.  Consequently, GNS domain names with a zTLD suffix are
       also globally unique.  Names with zTLDs suffixes are not human-
       readable.

   2.  Memorable petnames for zones: Users can configure local, human-
       readable references to zones.  Such petnames serve as zTLD
       monikers which provide convenient names for zones to the local
       operator.  The petnames may also be published as suggestions for
       other users searching for good label to use when referencing the
       respective zone.

   3.  A secure mapping from names to records: GNS allows zone owners to
       map labels to resource records or to delegate authority of names
       in the subdomain induced by a label to other zones.  Zone owners
       may choose to publish this information to make it available to
       other users.  Mappings are encrypted and signed using keys
       derived from the respective label before being published to
       remote storage.  When names are resolved, signatures on resource
       records including delegations are verified by the recursive
       resolver.

   In the remainder of this document, the "implementer" refers to the
   developer building a GNS implementation including the resolver, zone
   master, and supporting configuration such as start zones (see
   Section 7.1).

3.1.  Names and Zones

   It follows from the above that GNS does not support names which are
   simultaneously global, secure and human-readable.  Instead, names are
   either global and not human-readable or not globally unique and
   human-readable.  An example for a global name pointing to the record
   "example" in a zone is:

   example.000G006K2TJNMD9VTCYRX7BRVV3HAEPS15E6NHDXKPJA1KAJJEG9AFF884








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   Now consider the case where a user locally configured the petname
   "pet.gns.alt" for the zone with the "example" record of the name
   above.  The name "example.pet.gns.alt" would then point to the same
   record as the globally unique name above, but name resolution would
   only work on the local system where the "pet.gns.alt" petname is
   configured.

   The delegation of petnames and subsequent resolution of delegation
   builds on ideas from the Simple Distributed Security Infrastructure
   [SDSI].  In GNS, any user can create and manage any number of zones
   (see Section 4) if their system provides a zone master
   implementation.  For each zone, the zone type determines the
   respective set of cryptographic operations and the wire formats for
   encrypted data, public keys and signatures.  A zone can be populated
   with mappings from labels to resource records (see Section 5) by its
   owner.  A label can be mapped to a delegation record which results in
   the corresponding subdomain being delegated to another zone.
   Circular delegations are explicitly allowed, including delegating a
   subdomain to its immediate parent zone.  In order to support (legacy)
   applications as well as to facilitate the use of petnames, GNS
   defines auxiliary record types in addition to supporting existing DNS
   records.

3.2.  Publishing Binding Information

   Zone contents are encrypted and signed before being published in a
   remote key-value storage (see Section 6) as illustrated in Figure 1.
   In this process, unique zone identification is hidden from the
   network through the use of key blinding.  Key blinding allows the
   creation of signatures for zone contents using a blinded public/
   private key pair.  This blinding is realized using a deterministic
   key derivation from the original zone key and corresponding private
   key using record label values as inputs from which blinding factors
   are derived.  Specifically, the zone owner can derive blinded private
   keys for each record set published under a label, and a resolver can
   derive the corresponding blinded public keys.  It is expected that
   GNS implementations use decentralized remote storages such as
   distributed hash tables (DHT) in order to facilitate availability
   within a network without the need for dedicated infrastructure.
   Specification of such a distributed or decentralized storage is out
   of scope of this document, but possible existing implementations
   include those based on [RFC7363], [Kademlia] or [R5N].









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          Host A         |   Remote        |      Host B
                         |   Storage       |
                         |                 |
                         |    +---------+  |
                         |   /         /|  |
                Publish  |  +---------+ |  |  Publish
    +---------+ Records  |  |         | |  |  Records +---------+
    |  Zone   |----------|->| Record  | |<-|----------|  Zone   |
    | Master  |          |  | Storage | |  |          | Master  |
    +---------+          |  |         |/   |          +---------+
         A               |  +---------+    |               A
         |               |                 |               |
      +---------+        |                 |           +---------+
     /   |     /|        |                 |          /    |    /|
    +---------+ |        |                 |         +---------+ |
    |         | |        |                 |         |         | |
    |  Local  | |        |                 |         |  Local  | |
    |  Zones  | |        |                 |         |  Zones  | |
    |         |/         |                 |         |         |/
    +---------+          |                 |         +---------+

      Figure 1: An example diagram of two hosts publishing GNS zones.

   A zone master implementation SHOULD be provided as part of a GNS
   implementation to enable users to create and manage zones.  If this
   functionality is not implemented, names can still be resolved if zone
   keys for the initial step in the name resolution have been configured
   (see Section 7) or if the names end with a zTLD suffix.

3.3.  Resolving Names

   Applications use the resolver to lookup GNS names.  Starting from a
   configurable start zone, names are resolved by following zone
   delegations recursively as illustrated in Figure 2.  For each label
   in a name, the recursive GNS resolver fetches the respective record
   set from the storage layer (see Section 7).  Without knowledge of the
   label values and the zone keys, the different derived keys are
   unlinkable both to the original zone key and to each other.  This
   prevents zone enumeration (except via expensive online brute force
   attacks): To confirm affiliation of a query or the corresponding
   encrypted record set with a specific zone requires knowledge of both
   the zone key and the label, neither of which are disclosed to remote
   storage by the protocol.  At the same time, the blinded zone key and
   digital signatures associated with each encrypted record set allow
   resolvers and oblivious remote storage to verify the integrity of the
   published information without disclosing anything about the
   originating zone or the record sets.




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                              Local Host           |   Remote
                                                   |   Storage
                                                   |
                                                   |    +---------+
                                                   |   /         /|
                                                   |  +---------+ |
   +-----------+ Name     +----------+ Recursive   |  |         | |
   |           | Lookup   |          | Resolution  |  | Record  | |
   |Application|----------| Resolver |-------------|->| Storage | |
   |           |<---------|          |<------------|--|         |/
   +-----------+ Results  +----------+ Intermediate|  +---------+
                             A         Results     |
                             |                     |
                          +---------+              |
                         /   |     /|              |
                        +---------+ |              |
                        |         | |              |
                        |  Start  | |              |
                        |  Zones  | |              |
                        |         |/               |
                        +---------+                |

          Figure 2: High-level view of the GNS resolution process.

4.  Zones

   A zone in GNS is uniquely identified by its zone type and zone key.
   Each zone can be referenced by its zone Top-Level Domain (zTLD)
   string (see Section 4.1) which encodes the zone type and zone key.  A
   zone type (ztype) is a unique 32-bit number which corresponds to a
   resource record type number identifying a delegation record type in
   the GANA "GNS Record Types" registry [GANA].  The ztype is a unique
   identifier for the set cryptographic functions of the zone and the
   format of the delegation record type.  Any ztype registration MUST
   define the following set of cryptographic functions:

   KeyGen() -> d, zk  is a function to generate a new private key d and
      the corresponding public zone key zk.

   ZKDF(zk,label) -> zk'  is a zone key derivation function which blinds
      a zone key zk using a label. zk and zk' must be unlinkable.
      Furthermore, blinding zk with different values for the label must
      result in different, unlinkable zk' values.

   S-Encrypt(zk,label,expiration,plaintext) -> ciphertext  is a
      symmetric encryption function which encrypts the plaintext to
      derive ciphertext based on key material derived from the zone key
      zk, a label and an expiration timestamp.  In order to leverage



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      performance-enhancing caching features of certain underlying
      storages, in particular DHTs, a deterministic encryption scheme is
      recommended.

   S-Decrypt(zk,label,expiration,ciphertext) -> plaintext  is a
      symmetric decryption function which decrypts the ciphertext into
      plaintext based on key material derived from the zone key, a
      label, and an expiration timestamp.

   Sign(d,message) -> signature  is a function to sign a message using
      the private key d, yielding an unforgeable cryptographic
      signature.  In order to leverage performance-enhancing caching
      features of certain underlying storages, in particular DHTs, a
      deterministic signature scheme is recommended.

   Verify(zk,message,signature) -> boolean  is a function to verify the
      signature was created using the private key d corresponding to the
      zone key zk where d,zk := Keygen().  The function returns a
      boolean value of "TRUE" if the signature is valid, and otherwise
      "FALSE".

   SignDerived(d,label,message) -> signature  is a function to sign a
      message (typically encrypted record data) that can be verified
      using the derived zone key zk' := ZKDF(zk,label).  In order to
      leverage performance-enhancing caching features of certain
      underlying storages, in particular DHTs, a deterministic signature
      scheme is recommended.

   VerifyDerived(zk,label,message,signature) -> boolean  is function to
      verify the signature using the derived zone key zk' :=
      ZKDF(zk,label).  The function returns a boolean value of "TRUE" if
      the signature is valid, and otherwise "FALSE".

   The cryptographic functions of the default ztypes are specified with
   their corresponding delegation records in Section 5.1.  In order to
   support cryptographic agility, additional ztypes MAY be defined in
   the future which replace or update the default ztypes defined in this
   document.  All ztypes MUST be registered as dedicated zone delegation
   record types in the GANA "GNS Record Types" registry (see [GANA]).
   When defining new record types the cryptographic security
   considerations of this document apply, in particular Section 9.3.










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4.1.  Zone Top-Level Domain

   A zone Top-Level Domain (zTLD) is a string which encodes the zone
   type and zone key into a domain name suffix.  A zTLD is used as a
   globally unique references to a zone in the process of name
   resolution.  It is created by encoding a binary concatenation of the
   zone type and zone key (see Figure 3).  The used encoding is a
   variation of the Crockford Base32 encoding [CrockfordB32] called
   Base32GNS.  The encoding and decoding symbols for Base32GNS including
   this modification are defined in Figure 30.  The functions for
   encoding and decoding based on this table are called Base32GNS-Encode
   and Base32GNS-Decode, respectively.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |       ZONE TYPE       |      ZONE KEY         /
   +-----+-----+-----+-----+                       /
   /                                               /
   /                                               /
   +-----+-----+-----+-----+-----+-----+-----+-----+

              Figure 3: The binary representation of the zTLD

   The ZONE TYPE must be encoded in network byte order.  The format of
   the ZONE KEY depends entirely on the ZONE TYPE.

   Consequently, a zTLD is encoded and decoded as follows:

   zTLD := Base32GNS-Encode(ztype||zkey)
   ztype||zkey := Base32GNS-Decode(zTLD)

   where "||" is the concatenation operator.

   The zTLD can be used as-is as a rightmost label in a GNS name.  If an
   application wants to ensure DNS compatibility of the name, it MAY
   also represent the zTLD as follows: If the zTLD is less than or equal
   to 63 characters, it can be used as a zTLD as-is.  If the zTLD is
   longer than 63 characters, the zTLD is divided into smaller labels
   separated by the label separator.  Here, the most significant bytes
   of the "ztype||zkey" concatenation must be contained in the rightmost
   label of the resulting string and the least significant bytes in the
   leftmost label of the resulting string.  This allows the resolver to
   determine the ztype and zTLD length from the rightmost label and to
   subsequently determine how many labels the zTLD should span.  A GNS
   implementation MUST support the division of zTLDs in DNS compatible
   label lengths.  For example, assuming a zTLD of 130 characters, the
   division is:




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   zTLD[126..129].zTLD[63..125].zTLD[0..62]

4.2.  Zone Revocation

   In order to revoke a zone key, a signed revocation message MUST be
   published.  This message MUST be signed using the private key of the
   zone.  The revocation message is broadcast to the network.  The
   specification of the broadcast mechanism is out of scope for this
   document.  A possible broadcast mechanism for efficient flooding in a
   distributed network is implemented in [GNUnet].  Alternatively,
   revocation messages could also be distributed via a distributed
   ledger or a trusted central server.  To prevent flooding attacks, the
   revocation message MUST contain a proof of work (PoW).  The
   revocation message including the PoW MAY be calculated ahead of time
   to support timely revocation.

   For all occurrences below, "Argon2id" is the Password-based Key
   Derivation Function as defined in [RFC9106].  For the PoW
   calculations the algorithm is instantiated with the following
   parameters:

   S  The salt.  Fixed 16-byte string: "GnsRevocationPow".

   t  Number of iterations: 3

   m  Memory size in KiB: 1024

   T  Output length of hash in bytes: 64

   p  Parallelization parameter: 1

   v  Algorithm version: 0x13

   y  Algorithm type (Argon2id): 2

   X  Unused

   K  Unused

   Figure 4 illustrates the format of the data "P" on which the PoW is
   calculated.










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   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                      POW                      |
   +-----------------------------------------------+
   |                   TIMESTAMP                   |
   +-----------------------------------------------+
   |       ZONE TYPE       |    ZONE KEY           |
   +-----+-----+-----+-----+                       |
   /                                               /
   /                                               /
   +-----+-----+-----+-----+-----+-----+-----+-----+

                   Figure 4: The Format of the PoW Data.

   POW  A 64-bit value that is a solution to the PoW.  In network byte
      order.

   TIMESTAMP  denotes the absolute 64-bit date when the revocation was
      computed.  In microseconds since midnight (0 hour), January 1,
      1970 UTC in network byte order.

   ZONE TYPE  is the 32-bit zone type in network byte order.

   ZONE KEY  is the 256-bit public key zk of the zone which is being
      revoked.  The wire format of this value is defined by the ZONE
      TYPE.

   Usually, PoW schemes require to find one POW value such that a
   specific number of leading zeroes are found in the hash result.  This
   number is then referred to as the difficulty of the PoW.  In order to
   reduce the variance in time it takes to calculate the PoW, a valid
   GNS revocation requires that a number Z different PoWs must be found
   that on average have D leading zeroes.

   Given an average difficulty of D, the proofs have an expiration time
   of EPOCH.  Applications MAY calculate proofs with a difficulty that
   is higher than D by providing POW values where there are (on average)
   more than D bits of leading zeros.  With each additional bit of
   difficulty, the lifetime of the proof is prolonged by another EPOCH.
   Consequently, by calculating a more difficult PoW, the lifetime of
   the proof and thus the persistence of the revocation message can be
   increased on demand by the zone owner.

   The parameters are defined as follows:

   Z  The number of PoWs that are required.  Its value is fixed at 32.

   D  The lower limit of the average difficulty.  Its value is fixed at



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      22.

   EPOCH  A single epoch.  Its value is fixed at 365 days in
      microseconds.

   The revocation message wire format is illustrated in Figure 5.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   TIMESTAMP                   |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                      TTL                      |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                     POW_0                     |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                       ...                     |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                     POW_Z-1                   |
   +-----------------------------------------------+
   |       ZONE TYPE       |    ZONE KEY           |
   +-----+-----+-----+-----+                       |
   /                                               /
   /                                               /
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   SIGNATURE                   |
   /                                               /
   /                                               /
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+

               Figure 5: The Revocation Message Wire Format.

   TIMESTAMP  denotes the absolute 64-bit date when the revocation was
      computed.  In microseconds since midnight (0 hour), January 1,
      1970 UTC in network byte order.  This is the same value as the
      time stamp used in the individual PoW calculations.

   TTL  denotes the relative 64-bit time to live of the record in
      microseconds in network byte order.  The field SHOULD be set to
      EPOCH * 1.1.  Given an average number of leading zeros D', then
      the field value MAY be increased up to (D'-D+1) * EPOCH * 1.1.
      Validators MAY reject messages with lower or higher values when
      received.

   POW_i  The values calculated as part of the PoW, in network byte
      order.  Each POW_i MUST be unique in the set of POW values.  To
      facilitate fast verification of uniqueness, the POW values must be
      given in strictly monotonically increasing order in the message.



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   ZONE TYPE  The 32-bit zone type corresponding to the zone key in
      network byte order.

   ZONE KEY  is the public key zk of the zone which is being revoked and
      the key to be used to verify SIGNATURE.

   SIGNATURE  A signature over a time stamp and the zone zk of the zone
      which is revoked and corresponds to the key used in the PoW.  The
      signature is created using the Sign() function of the cryptosystem
      of the zone and the private key (see Section 4).

   The signature over the public key covers a 32-bit header prefixed to
   the time stamp and public key fields.  The header includes the key
   length and signature purpose.  The wire format is illustrated in
   Figure 6.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |         SIZE          |       PURPOSE (0x03)  |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   TIMESTAMP                   |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |       ZONE TYPE       |     ZONE KEY          |
   +-----+-----+-----+-----+                       |
   /                                               /
   /                                               /
   +-----+-----+-----+-----+-----+-----+-----+-----+

       Figure 6: The Wire Format of the Revocation Data for Signing.

   SIZE  A 32-bit value containing the length of the signed data in
      bytes in network byte order.

   PURPOSE  A 32-bit signature purpose flag.  The value of this field
      MUST be 3.  The value is encoded in network byte order.  It
      defines the context in which the signature is created so that it
      cannot be reused in other parts of the protocol including possible
      future extensions.  The value of this field corresponds to an
      entry in the GANA "GNUnet Signature Purpose" registry [GANA].

   TIMESTAMP  Field as defined in the revocation message above.

   ZONE TYPE  Field as defined in the revocation message above.

   ZONE KEY  Field as defined in the revocation message above.

   In order to validate a revocation the following steps MUST be taken:




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   1.  The signature MUST be verified against the zone key.

   2.  The set of POW values MUST NOT contain duplicates which MUST be
       checked by verifying that the values are strictly monotonically
       increasing.

   3.  The average number of leading zeroes D' resulting from the
       provided POW values MUST be greater than or equal to D.
       Implementers MUST NOT use an integer data type to calculate or
       represent D'.

   The TTL field in the revocation message is informational.  A
   revocation MAY be discarded without checking the POW values or the
   signature if the TTL (in combination with TIMESTAMP) indicates that
   the revocation has already expired.  The actual validity period of
   the revocation MUST be determined by examining the leading zeroes in
   the POW values.

   The validity period of the revocation is calculated as (D'-D+1) *
   EPOCH * 1.1.  The EPOCH is extended by 10% in order to deal with
   unsynchronized clocks.  The validity period added on top of the
   TIMESTAMP yields the expiration date.  If the current time is after
   the expiration date, the revocation is considered stale.

   Verified revocations MUST be stored locally.  The implementation MAY
   discard stale revocations and evict then from the local store at any
   time.

   Implementations MUST broadcast received revocations if they are valid
   and not stale.  Should the calculated validity period differ from the
   TTL field value, the calculated value MUST be used as TTL field value
   when forwarding the revocation message.  Systems might disagree on
   the current time, so implementations MAY use stale but otherwise
   valid revocations but SHOULD NOT broadcast them.  Forwarded stale
   revocations MAY be discarded.

   Any locally stored revocation MUST be considered during delegation
   record processing (see Section 7.3.4).

5.  Resource Records

   A GNS implementation SHOULD provide a mechanism to create and manage
   local zones as well as a persistence mechanism (such as a local
   database) for resource records.  A new local zone is established by
   selecting a zone type and creating a zone key pair.  If this
   mechanism is not implemented, no zones can be published in the
   storage (see Section 6) and name resolution is limited to non-local
   start zones (see Section 7.1).



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   A GNS resource record holds the data of a specific record in a zone.
   The resource record format is defined in Figure 7.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   EXPIRATION                  |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |    SIZE   |   FLAGS   |          TYPE         |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                      DATA                     /
   /                                               /
   /                                               /

                 Figure 7: The Resource Record Wire Format.

   EXPIRATION  denotes the absolute 64-bit expiration date of the
      record.  In microseconds since midnight (0 hour), January 1, 1970
      UTC in network byte order.

   SIZE  denotes the 16-bit size of the DATA field in bytes in network
      byte order.

   FLAGS  is a 16-bit bit field indicating special properties of the
      resource record.  The semantics of the different bits are defined
      below.

   TYPE  is the 32-bit resource record type in network byte order.  This
      type can be one of the GNS resource records as defined in
      Section 5 or a DNS record type as defined in [RFC1035] or any of
      the complementary standardized DNS resource record types.  Note
      that values below 2^16 are reserved for 16-bit DNS Resorce Record
      types allocated by IANA [RFC6895].  Values above 2^16 are
      allocated by the GANA "GNS Record Types" registry [GANA].

   DATA  the variable-length resource record data payload.  The content
      is defined by the respective type of the resource record.

   The FLAGS field is used to indicate special properties of the
   resource record.  An application creating resource records MUST set
   all bits in FLAGS to 0 unless it specifically understands and wants
   to set the respective flag.  As additional flags can be defined in
   future protocol versions, if an application or implementation
   encounters a flag which it does not recognize, it MUST be ignored.
   However, all implementations MUST understand the SHADOW and CRITICAL
   flags defined below.  Any combination of the flags specified below
   are valid.  Figure 8 illustrates the flag distribution in the 16-bit
   FLAGS field of a resource record:




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   0           13            14      15
   +--------...+-------------+-------+---------+
   | Reserved  |SUPPLEMENTAL |SHADOW |CRITICAL |
   +--------...+-------------+-------+---------+

              Figure 8: The Resource Record Flag Wire Format.

   CRITICAL  If this flag is set, it indicates that processing is
      critical.  Implementations that do not support the record type or
      are otherwise unable to process the record MUST abort resolution
      upon encountering the record in the resolution process.

   SHADOW  If this flag is set, this record MUST be ignored by resolvers
      unless all (other) records of the same record type have expired.
      Used to allow zone publishers to facilitate good performance when
      records change by allowing them to put future values of records
      into the storage.  This way, future values can propagate and can
      be cached before the transition becomes active.

   SUPPLEMENTAL  This is a supplemental record.  It is provided in
      addition to the other records.  This flag indicates that this
      record is not explicitly managed alongside the other records under
      the respective name but might be useful for the application.

5.1.  Zone Delegation Records

   This section defines the initial set of zone delegation record types.
   Any implementation SHOULD support all zone types defined here and MAY
   support any number of additional delegation records defined in the
   GANA "GNS Record Types" registry (see [GANA]).  Not supporting some
   zone types will result in resolution failures in case the respective
   zone type is encountered.  This can be a valid choice if some zone
   delegation record types have been determined to be cryptographically
   insecure.  Zone delegation records MUST NOT be stored and published
   under the apex label.  A zone delegation record type value is the
   same as the respective ztype value.  The ztype defines the
   cryptographic primitives for the zone that is being delegated to.  A
   zone delegation record payload contains the public key of the zone to
   delegate to.  A zone delegation record MUST have the CRITICAL flag
   set and MUST be the only non-supplemental record under a label.
   There MAY be inactive records of the same type which have the SHADOW
   flag set in order to facilitate smooth key rollovers.

   In the following, "||" is the concatenation operator of two byte
   strings.  The algorithm specification uses character strings such as
   GNS labels or constant values.  When used in concatenations or as
   input to functions the null-terminator of the character strings MUST
   NOT be included.



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5.1.1.  PKEY

   In GNS, a delegation of a label to a zone of type "PKEY" is
   represented through a PKEY record.  The PKEY DATA entry wire format
   can be found in Figure 9.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   PUBLIC KEY                  |
   |                                               |
   |                                               |
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+

                      Figure 9: The PKEY Wire Format.

   PUBLIC KEY  A 256-bit Ed25519 public key.

   For PKEY zones the zone key material is derived using the curve
   parameters of the twisted Edwards representation of Curve25519
   [RFC7748] (the reasoning behind choosing this curve can be found in
   Section 9.3) with the ECDSA scheme [RFC6979].  The following naming
   convention is used for the cryptographic primitives of PKEY zones:

   d  is a 256-bit Ed25519 private key (private scalar).

   zk  is the Ed25519 public zone key corresponding to d.

   p  is the prime of edwards25519 as defined in [RFC7748], i.e.  2^255
      - 19.

   G  is the group generator (X(P),Y(P)).  With X(P),Y(P) of
      edwards25519 as defined in [RFC7748].

   L  is the order of the prime-order subgroup of edwards25519 in
      [RFC7748].

   KeyGen()  The generation of the private scalar d and the curve point
      zk := d*G (where G is the group generator of the elliptic curve)
      as defined in Section 2.2. of [RFC6979] represents the KeyGen()
      function.

   The zone type and zone key of a PKEY are 4 + 32 bytes in length.
   This means that a zTLD will always fit into a single label and does
   not need any further conversion.  Given a label, the output zk' of
   the ZKDF(zk,label) function is calculated as follows for PKEY zones:





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   ZKDF(zk,label):
     PRK_h := HKDF-Extract ("key-derivation", zk)
     h := HKDF-Expand (PRK_h, label || "gns", 512 / 8)
     zk' := (h mod L) * zk
     return zk'

   The PKEY cryptosystem uses a hash-based key derivation function
   (HKDF) as defined in [RFC5869], using SHA-512 [RFC6234] for the
   extraction phase and SHA-256 [RFC6234] for the expansion phase.
   PRK_h is key material retrieved using an HKDF using the string "key-
   derivation" as salt and the zone key as initial keying material.  h
   is the 512-bit HKDF expansion result and must be interpreted in
   network byte order.  The expansion information input is a
   concatenation of the label and the string "gns".  The multiplication
   of zk with h is a point multiplication, while the multiplication of d
   with h is a scalar multiplication.

   The Sign() and Verify() functions for PKEY zones are implemented
   using 512-bit ECDSA deterministic signatures as specified in
   [RFC6979].  The same functions can be used for derived keys:

   SignDerived(d,label,message):
     zk := d * G
     PRK_h := HKDF-Extract ("key-derivation", zk)
     h := HKDF-Expand (PRK_h, label || "gns", 512 / 8)
     d' := (h * d) mod L
     return Sign(d',message)

   A signature (R,S) is valid if the following holds:

   VerifyDerived(zk,label,message,signature):
     zk' := ZKDF(zk,label)
     return Verify(zk',message,signature)

   The S-Encrypt() and S-Decrypt() functions use AES in counter mode as
   defined in [MODES] (CTR-AES-256):















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   S-Encrypt(zk,label,expiration,plaintext):
     PRK_k := HKDF-Extract ("gns-aes-ctx-key", zk)
     PRK_n := HKDF-Extract ("gns-aes-ctx-iv", zk)
     K := HKDF-Expand (PRK_k, label, 256 / 8)
     NONCE := HKDF-Expand (PRK_n, label, 32 / 8)
     IV := NONCE || expiration || 0x0000000000000001
     return CTR-AES256(K, IV, plaintext)

   S-Decrypt(zk,label,expiration,ciphertext):
     PRK_k := HKDF-Extract ("gns-aes-ctx-key", zk)
     PRK_n := HKDF-Extract ("gns-aes-ctx-iv", zk)
     K := HKDF-Expand (PRK_k, label, 256 / 8)
     NONCE := HKDF-Expand (PRK_n, label, 32 / 8)
     IV := NONCE || expiration || 0x0000000000000001
     return CTR-AES256(K, IV, ciphertext)

   The key K and counter IV are derived from the record label and the
   zone key zk using a hash-based key derivation function (HKDF) as
   defined in [RFC5869].  SHA-512 [RFC6234] is used for the extraction
   phase and SHA-256 [RFC6234] for the expansion phase.  The output
   keying material is 32 bytes (256 bits) for the symmetric key and 4
   bytes (32 bits) for the nonce.  The symmetric key K is a 256-bit AES
   [RFC3826] key.

   The nonce is combined with a 64-bit initialization vector and a
   32-bit block counter as defined in [RFC3686].  The block counter
   begins with the value of 1, and it is incremented to generate
   subsequent portions of the key stream.  The block counter is a 32-bit
   integer value in network byte order.  The initialization vector is
   the expiration time of the resource record block in network byte
   order.  The resulting counter (IV) wire format can be found in
   Figure 10.

   0     8     16    24    32
   +-----+-----+-----+-----+
   |         NONCE         |
   +-----+-----+-----+-----+
   |       EXPIRATION      |
   |                       |
   +-----+-----+-----+-----+
   |      BLOCK COUNTER    |
   +-----+-----+-----+-----+

                 Figure 10: The Block Counter Wire Format.







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5.1.2.  EDKEY

   In GNS, a delegation of a label to a zone of type "EDKEY" is
   represented through a EDKEY record.  The EDKEY DATA entry wire format
   is illustrated in Figure 11.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   PUBLIC KEY                  |
   |                                               |
   |                                               |
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+

                   Figure 11: The EDKEY DATA Wire Format.

   PUBLIC KEY  A 256-bit EdDSA zone key.

   For EDKEY zones the zone key material is derived using the curve
   parameters of the twisted edwards representation of Curve25519
   [RFC7748] (a.k.a.  Ed25519) with the Ed25519 scheme [ed25519] as
   specified in [RFC8032].  The following naming convention is used for
   the cryptographic primitives of EDKEY zones:

   d  is a 256-bit EdDSA private key.

   a  is is an integer derived from d using the SHA-512 hash function as
      defined in [RFC8032].

   zk  is the EdDSA public key corresponding to d.  It is defined as the
      curve point a*G where G is the group generator of the elliptic
      curve as defined in [RFC8032].

   p  is the prime of edwards25519 as defined in [RFC8032], i.e.  2^255
      - 19.

   G  is the group generator (X(P),Y(P)).  With X(P),Y(P) of
      edwards25519 as defined in [RFC8032].

   L  is the order of the prime-order subgroup of edwards25519 in
      [RFC8032].

   KeyGen()  The generation of the private key d and the associated
      public key zk := a*G where G is the group generator of the
      elliptic curve and a is an integer derived from d using the
      SHA-512 hash function as defined in Section 5.1.5 of [RFC8032]
      represents the KeyGen() function.




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   The zone type and zone key of an EDKEY are 4 + 32 bytes in length.
   This means that a zTLD will always fit into a single label and does
   not need any further conversion.

   The "EDKEY" ZKDF instantiation is based on [Tor224].  The calculation
   of a is defined in Section 5.1.5 of [RFC8032].  Given a label, the
   output of the ZKDF function is calculated as follows:

   ZKDF(zk,label):
     /* Calculate the blinding factor */
     PRK_h := HKDF-Extract ("key-derivation", zk)
     h := HKDF-Expand (PRK_h, label || "gns", 512 / 8)
     /* Ensure that h == h mod L */
     h[31] &= 7

     zk' := h * zk
     return zk'

   Implementers SHOULD employ a constant time scalar multiplication for
   the constructions above to protect against timing attacks.
   Otherwise, timing attacks could leak private key material if an
   attacker can predict when a system starts the publication process.

   The EDKEY cryptosystem uses a hash-based key derivation function
   (HKDF) as defined in [RFC5869], using SHA-512 [RFC6234] for the
   extraction phase and HMAC-SHA256 [RFC6234] for the expansion phase.
   PRK_h is key material retrieved using an HKDF using the string "key-
   derivation" as salt and the zone key as initial keying material.  The
   blinding factor h is the 512-bit HKDF expansion result.  The
   expansion information input is a concatenation of the label and the
   string "gns".  The result of the HKDF must be clamped and interpreted
   in network byte order.  a is the 256-bit integer corresponding to the
   256-bit private key d.  The multiplication of zk with h is a point
   multiplication, while the division and multiplication of a and a1
   with the co-factor are integer operations.

   The Sign(d,message) and Verify(zk,message,signature) procedures MUST
   be implemented as defined in [RFC8032].













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   Signatures for EDKEY zones use a derived private scalar d' which is
   not compliant with [RFC8032].  As the corresponding private key to
   the derived private scalar is not known, it is not possible to
   deterministically derive the signature part R according to [RFC8032].
   Instead, signatures MUST be generated as follows for any given
   message and private zone key: A nonce is calculated from the highest
   32 bytes of the expansion of the private key d and the blinding
   factor h.  The nonce is then hashed with the message to r.  This way,
   the full derivation path is included in the calculation of the R
   value of the signature, ensuring that it is never reused for two
   different derivation paths or messages.

   SignDerived(d,label,message):
     /* Key expansion */
     dh := SHA-512 (d)
     /* EdDSA clamping */
     a := dh[0..31]
     a[0] &= 248
     a[31] &= 127
     a[31] |= 64
     /* Calculate zk corresponding to d */
     zk := a * G

     /* Calculate blinding factor */
     PRK_h := HKDF-Extract ("key-derivation", zk)
     h := HKDF-Expand (PRK_h, label || "gns", 512 / 8)
     /* Ensure that h == h mod L */
     h[31] &= 7

     zk' := h * zk
     a1 := a >> 3
     a2 := (h * a1) mod L
     d' := a2 << 3
     nonce := SHA-256 (dh[32..63] || h)
     r := SHA-512 (nonce || message)
     R := r * G
     S := r + SHA-512(R || zk' || message) * d' mod L
     return (R,S)

   A signature (R,S) is valid if the following holds:

   VerifyDerived(zk,label,message,signature):
     zk' := ZKDF(zk,label)
     (R,S) := signature
     return S * G == R + SHA-512(R, zk', message) * zk'

   The S-Encrypt() and S-Decrypt() functions use XSalsa20 as defined in
   [XSalsa20] (XSalsa20-Poly1305):



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   S-Encrypt(zk,label,expiration,plaintext):
     PRK_k := HKDF-Extract ("gns-xsalsa-ctx-key", zk)
     PRK_n := HKDF-Extract ("gns-xsalsa-ctx-iv", zk)
     K := HKDF-Expand (PRK_k, label, 256 / 8)
     NONCE := HKDF-Expand (PRK_n, label, 128 / 8)
     IV := NONCE || expiration
     return XSalsa20-Poly1305(K, IV, plaintext)

   S-Decrypt(zk,label,expiration,ciphertext):
     PRK_k := HKDF-Extract ("gns-xsalsa-ctx-key", zk)
     PRK_n := HKDF-Extract ("gns-xsalsa-ctx-iv", zk)
     K := HKDF-Expand (PRK_k, label, 256 / 8)
     NONCE := HKDF-Expand (PRK_n, label, 128 / 8)
     IV := NONCE || expiration
     return XSalsa20-Poly1305(K, IV, ciphertext)

   The result of the XSalsa20-Poly1305 encryption function is the
   encrypted ciphertext followed by the 128-bit authentication tag.
   Accordingly, the length of encrypted data equals the length of the
   data plus the 16 bytes of the authentication tag.

   The key K and counter IV are derived from the record label and the
   zone key zk using a hash-based key derivation function (HKDF) as
   defined in [RFC5869].  SHA-512 [RFC6234] is used for the extraction
   phase and SHA-256 [RFC6234] for the expansion phase.  The output
   keying material is 32 bytes (256 bits) for the symmetric key and 16
   bytes (128 bits) for the NONCE.  The symmetric key K is a 256-bit
   XSalsa20 [XSalsa20] key.  No additional authenticated data (AAD) is
   used.

   The nonce is combined with an 8 byte initialization vector.  The
   initialization vector is the expiration time of the resource record
   block in network byte order.  The resulting counter (IV) wire format
   is illustrated in Figure 12.

   0     8     16    24    32
   +-----+-----+-----+-----+
   |         NONCE         |
   |                       |
   |                       |
   |                       |
   +-----+-----+-----+-----+
   |       EXPIRATION      |
   |                       |
   +-----+-----+-----+-----+

            Figure 12: The Counter Block Initialization Vector.




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5.2.  Redirection Records

   Redirect records are used to redirect resolution.  Any implementation
   SHOULD support all redirection record types defined here and MAY
   support any number of additional redirection records defined in the
   GANA "GNS Record Types" registry [GANA].  Redirection records MUST
   have the CRITICAL flag set.  Not supporting some record types can
   result in resolution failures.  This can be a valid choice if some
   redirection record types have been determined to be insecure, or if
   an application has reasons to not support redirection to DNS for
   reasons such as complexity or security.  Redirection records MUST NOT
   be stored and published under the apex label.

5.2.1.  REDIRECT

   A REDIRECT record is the GNS equivalent of a CNAME record in DNS.  A
   REDIRECT record MUST be the only non-supplemental record under a
   label.  There MAY be inactive records of the same type which have the
   SHADOW flag set in order to facilitate smooth changes of redirection
   targets.  No other records are allowed.  Details on processing of
   this record is defined in Section 7.3.1.  A REDIRECT DATA entry is
   illustrated in Figure 13.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   REDIRECT NAME               |
   /                                               /
   /                                               /
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+

                 Figure 13: The REDIRECT DATA Wire Format.

   REDIRECT NAME  The name to continue with.  The value of a redirect
      record can be a regular name, or a relative name.  Relative GNS
      names are indicated by an extension label (U+002B, "+") as
      rightmost label.  The string is UTF-8 encoded and 0-terminated.

5.2.2.  GNS2DNS

   A GNS2DNS record delegates resolution to DNS.  The resource record
   contains a DNS name for the resolver to continue with in DNS followed
   by a DNS server.  Both names are in the format defined in [RFC1034]
   for DNS names.  There MAY be multiple GNS2DNS records under a label.
   There MAY also be DNSSEC DS records or any other records used to
   secure the connection with the DNS servers under the same label.
   There MAY be inactive records of the same type(s) which have the
   SHADOW flag set in order to facilitate smooth changes of redirection



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   targets.  No other non-supplemental record types are allowed in the
   same record set.  A GNS2DNS DATA entry is illustrated in Figure 14.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                      NAME                     |
   /                                               /
   /                                               /
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                 DNS SERVER NAME               |
   /                                               /
   /                                               /
   |                                               |
   +-----------------------------------------------+

                  Figure 14: The GNS2DNS DATA Wire Format.

   NAME  The name to continue with in DNS.  The value is UTF-8 encoded
      and 0-terminated.

   DNS SERVER NAME  The DNS server to use.  This value can be an IPv4
      address in dotted-decimal form or an IPv6 address in colon-
      hexadecimal form or a DNS name.  It can also be a relative GNS
      name ending with a "+" as the rightmost label.  The implementation
      MUST check the string syntactically for an IP address in the
      respective notation before checking for a relative GNS name.  If
      all three checks fail, the name MUST be treated as a DNS name.
      The value is UTF-8 encoded and 0-terminated.

   NOTE: If an application uses DNS names obtained from GNS2DNS records
   in a DNS request they MUST first be converted to an IDNA compliant
   representation [RFC5890].

5.3.  Auxiliary Records

   This section defines the initial set of auxiliary GNS record types.
   Any implementation SHOULD be able to process the specified record
   types according to Section 7.3.

5.3.1.  LEHO

   This record is used to provide a hint for LEgacy HOstnames:
   Applications can use the GNS to lookup IPv4 or IPv6 addresses of
   internet services.  However, sometimes connecting to such services
   does not only require the knowledge of an address and port, but also
   requires the canonical DNS name of the service to be transmitted over
   the transport protocol.  In GNS, legacy host name records provide



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   applications the DNS name that is required to establish a connection
   to such a service.  The most common use case is HTTP virtual hosting
   and TLS Server Name Indication [RFC6066], where a DNS name must be
   supplied in the HTTP "Host"-header and the TLS handshake,
   respectively.  Using a GNS name in those cases might not work as it
   might not be globally unique.  Furthermore, even if uniqueness is not
   an issue, the legacy service might not even be aware of GNS.

   A LEHO resource record is expected to be found together in a single
   resource record with an IPv4 or IPv6 address.  A LEHO DATA entry is
   illustrated in Figure 15.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                 LEGACY HOSTNAME               |
   /                                               /
   /                                               /
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+

                   Figure 15: The LEHO DATA Wire Format.

   LEGACY HOSTNAME  A UTF-8 string (which is not 0-terminated)
      representing the legacy hostname.

   NOTE: If an application uses a LEHO value in an HTTP request header
   (e.g.  "Host:" header) it MUST be converted to an IDNA compliant
   representation [RFC5890].

5.3.2.  NICK

   Nickname records can be used by zone administrators to publish a
   label that a zone prefers to have used when it is referred to.  This
   is a suggestion to other zones what label to use when creating a
   delegation record (Section 5.1) containing this zone key.  This
   record SHOULD only be stored locally under the apex label "@" but MAY
   be returned with record sets under any label as a supplemental
   record.  Section 7.3.5 details how a resolver must process
   supplemental and non-supplemental NICK records.  A NICK DATA entry is
   illustrated in Figure 16.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                  NICKNAME                     |
   /                                               /
   /                                               /
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+



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                   Figure 16: The NICK DATA Wire Format.

   NICKNAME  A UTF-8 string (which is not 0-terminated) representing the
      preferred label of the zone.  This string MUST be a valid GNS
      label.

5.3.3.  BOX

   GNS lookups are expected to return all of the required useful
   information in one record set.  This avoids unnecessary additional
   lookups and cryptographically ties together information that belongs
   together, making it impossible for an adversarial storage to provide
   partial answers that might omit information critical for security.

   This general strategy is incompatible with the special labels used by
   DNS for SRV and TLSA records.  Thus, GNS defines the BOX record
   format to box up SRV and TLSA records and include them in the record
   set of the label they are associated with.  For example, a TLSA
   record for "_https._tcp.example.org" will be stored in the record set
   of "example.org" as a BOX record with service (SVC) 443 (https) and
   protocol (PROTO) 6 (tcp) and record TYPE "TLSA".  For reference, see
   also [RFC2782].  A BOX DATA entry is illustrated in Figure 17.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |   PROTO   |    SVC    |       TYPE            |
   +-----------+-----------------------------------+
   |                 RECORD DATA                   |
   /                                               /
   /                                               /
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+

                    Figure 17: The BOX DATA Wire Format.

   PROTO  the 16-bit protocol number in network byte order.  Values
      below 2^8 are reserved for 8-bit Internet Protocol numbers
      allocated by IANA [RFC5237] (e.g. 6 for TCP).  Values above 2^8
      are allocated by the GANA "Overlay Protocols" registry [GANA].

   SVC  the 16-bit service value of the boxed record in network byte
      order.  In case of TCP and UDP it is the port number.

   TYPE  is the 32-bit record type of the boxed record in network byte
      order.

   RECORD DATA  is a variable length field containing the "DATA" format




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      of TYPE as defined for the respective TYPE.  Thus, for TYPE values
      below 2^16, the format is the same as the respective record type's
      binary format in DNS.

6.  Record Encoding for Remote Storage

   Any API which allows storing a block under a 512-bit key and
   retrieving one or more blocks from a key can be used by an
   implementation for remote storage.  To be useful, the API MUST permit
   storing at least 176 byte blocks to be able to support the defined
   zone delegation record encodings, and SHOULD allow at least 1024 byte
   blocks.  In the following, it is assumed that an implementation
   realizes two procedures on top of a storage:

   PUT(key,block)
   GET(key) -> block

   A GNS implementation publishes blocks in accordance to the properties
   and recommendations of the underlying remote storage.  This can
   include a periodic refresh operation to preserve the availability of
   published blocks.

   There is no mechanism to explicitly delete individual blocks from
   remote storage.  However, blocks include an EXPIRATION field which
   guides remote storage implementations to decide when to delete
   blocks.  Given multiple blocks for the same key, remote storage
   implementations SHOULD try to preserve and return the block with the
   largest EXPIRATION value.

   All resource records from the same zone sharing the same label are
   encrypted and published together in a single resource records block
   (RRBLOCK) in the remote storage under a key q as illustrated in
   Figure 18.  A GNS implementation MUST NOT include expired resource
   records in blocks.  An implementation MUST use the PUT storage
   procedure when record sets change to update the zone contents.
   Implementations MUST ensure that the EXPIRATION fields of RRBLOCKs
   increases strictly monotonically for every change, even if the
   smallest expiration time of records in the block does not.













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                              Local Host          |   Remote
                                                  |   Storage
                                                  |
                                                  |    +---------+
                                                  |   /         /|
                                                  |  +---------+ |
   +-----------+                                  |  |         | |
   |           |       +---------+PUT(q, RRBLOCK) |  | Record  | |
   |    User   |       |  Zone   |----------------|->| Storage | |
   |           |       | Master  |                |  |         |/
   +-----------+       +---------+                |  +---------+
        |                     A                   |
        |                     | Zone records      |
        |                     | grouped by label  |
        |                     |                   |
        |                 +---------+             |
        |Create / Delete /    |    /|             |
        |and Update     +---------+ |             |
        |Local Zones    |         | |             |
        |               |  Local  | |             |
        +-------------->|  Zones  | |             |
                        |         |/              |
                        +---------+               |

        Figure 18: Management and publication of local zones in the
                            distributed storage.

   The storage key derivation and records block creation is specified in
   the following sections and illustrated in Figure 19.






















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   +----------+ +-------+ +------------+ +-------------+
   | Zone Key | | Label | | Record Set | | Private Key |
   +----------+ +-------+ +------------+ +-------------+
       |          |            |               |
       |          |            v               |
       |          |           +-----------+    |
       |          +---------->| S-Encrypt |    |
       +----------|---------->+-----------+    |
       |          |               |    |       |
       |          |               |    v       v
       |          |               |   +-------------+
       |          +---------------|-->| SignDerived |
       |          |               |   +-------------+
       |          |               |        |
       |          v               v        v
       |      +------+        +---------------+
       +----->| ZKDF |------->| Records Block |
              +------+        +---------------+
                 |
                 v
              +------+        +-------------+
              | Hash |------->| Storage Key |
              +------+        +-------------+

        Figure 19: Storage key and records block creation overview.

6.1.  The Storage Key

   The storage key is derived from the zone key and the respective label
   of the contained records.  The required knowledge of both zone key
   and label in combination with the similarly derived symmetric secret
   keys and blinded zone keys ensures query privacy (see [RFC8324],
   Section 3.5).

   Given a label, the storage key q is derived as follows:

   q := SHA-512 (ZKDF(zk, label))

   label  is a UTF-8 string under which the resource records are
      published.

   zk  is the zone key.

   q  Is the 512-bit storage key under which the resource records block
      is published.  It is the SHA-512 hash [RFC6234] over the derived
      zone key.





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6.2.  Plaintext Record Data (RDATA)

   GNS records from a zone are grouped by their labels such that all
   records under the same label published together as a single block in
   the storage.  Such grouped record sets MAY be paired with
   supplemental records.

   Record data (RDATA) is the format used to encode such a group of GNS
   records.  The binary format of RDATA is illustrated in Figure 20.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                 EXPIRATION                    |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |    SIZE   |    FLAGS  |        TYPE           |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                      DATA                     /
   /                                               /
   /                                               /
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   EXPIRATION                  |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |    SIZE   |    FLAGS  |        TYPE           |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                     DATA                      /
   /                                               /
   +-----+-----+-----+-----+-----+-----+-----+-----+
   /                     PADDING                   /
   /                                               /
   +-----+-----+-----+-----+-----+-----+-----+-----+

                     Figure 20: The RDATA Wire Format.

   EXPIRATION, SIZE, TYPE, FLAGS and DATA  These fields were defined in
      the resource record format in Section 5.

   PADDING  When serializing records into RDATA, a GNS implementation
      MUST ensure that the size of the RDATA is a power of two using the
      padding field.  The field MUST be set to zero and MUST be ignored
      on receipt.  As a special exception, record sets with (only) a
      zone delegation record type are never padded.










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6.3.  The Resource Records Block

   The resource records grouped in an RDATA are encrypted using the
   S-Encrypt() function defined by the zone type of the zone to which
   the resource records belong and prefixed with meta data into a
   resource record block (RRBLOCK) for remote storage.  The GNS RRBLOCK
   wire format is illustrated in Figure 21.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |          SIZE         |    ZONE TYPE          |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   /                  ZONE KEY                     /
   /                  (BLINDED)                    /
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   SIGNATURE                   |
   /                                               /
   /                                               /
   |                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   EXPIRATION                  |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                    BDATA                      /
   /                                               /
   /                                               |
   +-----+-----+-----+-----+-----+-----+-----+-----+

                    Figure 21: The RRBLOCK Wire Format.

   SIZE  A 32-bit value containing the length of the block in bytes in
      network byte order.  Despite the message format's use of a 32-bit
      value, implementations MAY refuse to publish blocks beyond a
      certain size significantly below the theoretical block size limit
      of 4 GB.

   ZONE TYPE  is the 32-bit ztype in network byte order.

   ZONE KEY (BLINDED)  is the blinded zone key "ZKDF(zk, label)" to be
      used to verify SIGNATURE.  The length and format of the blinded
      public key depends on the ztype.

   SIGNATURE  The signature is computed over the EXPIRATION and BDATA
      fields as detailed in Figure 22.  The length and format of the
      signature depends on the ztype.  The signature is created using
      the SignDerived() function of the cryptosystem of the zone (see
      Section 4).




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   EXPIRATION  Specifies when the RRBLOCK expires and the encrypted
      block SHOULD be removed from the storage and caches as it is
      likely stale.  However, applications MAY continue to use non-
      expired individual records until they expire.  The value MUST be
      set to the maximum of the expiration time of the resource record
      contained within this block with the smallest expiration time and
      the previous EXPIRATION value (if any) plus one to ensure strict
      monotonicity (see Section 9.3).  If the RDATA includes shadow
      records, then the maximum expiration time of all shadow records
      with matching type and the expiration times of the non-shadow
      records is considered.  This is a 64-bit absolute date in
      microseconds since midnight (0 hour), January 1, 1970 UTC in
      network byte order.

   BDATA  The encrypted RDATA computed using S-Encrypt() with the zone
      key, label and expiration time as additional inputs.  Its ultimate
      size and content are determined by the S-Encrypt() function of the
      ztype.

   The signature over the public key covers a 32-bit pseudo header
   conceptually prefixed to the EXPIRATION and the BDATA fields.  The
   wire format is illustrated in Figure 22.

   0     8     16    24    32    40    48    56
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |         SIZE          |       PURPOSE (0x0F)  |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                   EXPIRATION                  |
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                    BDATA                      |
   /                                               /
   /                                               /
   +-----+-----+-----+-----+-----+-----+-----+-----+

     Figure 22: The Wire Format used for creating the signature of the
                                  RRBLOCK.

   SIZE  A 32-bit value containing the length of the signed data in
      bytes in network byte order.

   PURPOSE  A 32-bit signature purpose flag in network byte order.  The
      value of this field MUST be 15.  It defines the context in which
      the signature is created so that it cannot be reused in other
      parts of the protocol including possible future extensions.  The
      value of this field corresponds to an entry in the GANA "GNUnet
      Signature Purpose" registry [GANA].

   EXPIRATION  Field as defined in the RRBLOCK message above.



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   BDATA  Field as defined in the RRBLOCK message above.

7.  Name Resolution

   Names in GNS are resolved by recursively querying the record storage.
   Recursive in this context means that a resolver does not provide
   intermediate results for a query to the application.  Instead, it
   MUST respond to a resolution request with either the requested
   resource record or an error message in case resolution fails.
   Figure 23 illustrates how an application requests the lookup of a GNS
   name (1).  The application MAY provide a desired record type to the
   resolver.  Subsequently, a Start Zone is determined (2) and the
   recursive resolution process started.  This is where the desired
   record type is used to guide processing.  For example, if a zone
   delegation record type is requested, the resolution of the apex label
   in that zone must be skipped, as the desired record is already found.
   Details on how the resolution process is initiated and each iterative
   result (3a,3b) in the resolution is processed are provided in the
   sections below.  The results of the lookup are eventually returned to
   the application (4).  The implementation MUST NOT filter the returned
   resource record sets according to the desired record type.  Filtering
   of record sets is typically done by the application.

                              Local Host             |   Remote
                                                     |   Storage
                                                     |
                                                     |    +---------+
                                                     |   /         /|
                                                     |  +---------+ |
   +-----------+ (1) Name +----------+               |  |         | |
   |           | Lookup   |          | (3a) GET(q)   |  | Record  | |
   |Application|----------| Resolver |---------------|->| Storage | |
   |           |<---------|          |<--------------|--|         |/
   +-----------+ (4)      +----------+ (3b) RRBLOCK  |  +---------+
                 Records     A                       |
                             |                       |
        (2) Determination of |                       |
            Start Zone       |                       |
                             |                       |
                          +---------+                |
                         /   |     /|                |
                        +---------+ |                |
                        |         | |                |
                        |  Start  | |                |
                        |  Zones  | |                |
                        |         |/                 |
                        +---------+                  |




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              Figure 23: The recursive GNS resolution process.

7.1.  Start Zones

   The resolution of a GNS name starts by identifying the start zone
   suffix.  Once the start zone suffix is identified, recursive
   resolution of the remainder of the name is initiated (see
   Section 7.2).  There are two types of start zone suffixes: zTLDs and
   local suffix-to-zone mappings.  The choice of available suffix-to-
   zone mappings is at the sole discretion of the local system
   administrator or user.  This property addresses the issue of a single
   hierarchy with a centrally controlled root and the related issue of
   distribution and management of root servers in DNS (see [RFC8324],
   Sections 3.10 and 3.12).

   For names ending with a zTLD the start zone is explicitly given in
   the suffix of the name to resolve.  In order to ensure uniqueness of
   names with zTLDs any implementation MUST use the given zone as start
   zone.  An implementation MUST first try to interpret the rightmost
   label of the given name as the beginning of a zTLD (see Section 4.1).
   If the rightmost label cannot be (partially) decoded or if it does
   not indicate a supported ztype, the name is treated as a normal name
   and start zone discovery MUST continue with finding a local suffix-
   to-zone mapping.  If a valid ztype can be found in the rightmost
   label, the implementation MUST try to synthesize and decode the zTLD
   to retrieve the start zone key according to Section 4.1.  If the zTLD
   cannot be synthesized or decoded, the resolution of the name fails
   and an error is returned to the application.  Otherwise, the zone key
   MUST be used as the start zone:

   Example name: www.example.<zTLD>
   => Start zone: zk of type ztype
   => Name to resolve from start zone: www.example

   For names not ending with a zTLD the resolver MUST determine the
   start zone through a local suffix-to-zone mapping.  Suffix-to-zone
   mappings MUST be configurable through a local configuration file or
   database by the user or system administrator.  A suffix MAY consist
   of multiple GNS labels concatenated with a label separator.  If
   multiple suffixes match the name to resolve, the longest matching
   suffix MUST be used.  The suffix length of two results MUST NOT be
   equal.  This indicates a misconfiguration and the implementation MUST
   return an error.  The following is a non-normative example mapping of
   start zones:







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   Example name: www.example.xyz.gns.alt
   Local suffix mappings:
   xyz.gns.alt = zTLD0 := Base32GNS(ztype0||zk0)
   example.xyz.gns.alt = zTLD1 := Base32GNS(ztype1||zk1)
   example.com.gns.alt = zTLD2 := Base32GNS(ztype2||zk2)
   ...
   => Start zone: zk1
   => Name to resolve from start zone: www

   The process given above MAY be supplemented with other mechanisms if
   the particular application requires a different process.  If no start
   zone can be discovered, resolution MUST fail and an error MUST be
   returned to the application.

7.2.  Recursion

   In each step of the recursive name resolution, there is an
   authoritative zone zk and a name to resolve.  The name MAY be empty.
   If the name is empty, it is interpreted as the apex label "@".
   Initially, the authoritative zone is the start zone.

   From here, the following steps are recursively executed, in order:

   1.  Extract the right-most label from the name to look up.

   2.  Calculate q using the label and zk as defined in Section 6.1.

   3.  Perform a storage query GET(q) to retrieve the RRBLOCK.

   4.  Check that (a) the block is not expired, (b) the SHA-512 hash of
       the derived authoritative zone key zk' from the RRBLOCK matches
       the query q, and (c) the signature is valid.  If any of these
       tests fail, the RRBLOCK MUST be ignored and, if applicable, the
       storage lookup GET(q) MUST continue to look for other RRBLOCKs.

   5.  Obtain the RDATA by decrypting the BDATA contained in the RRBLOCK
       using S-Decrypt() as defined by the zone type, effectively
       inverting the process described in Section 6.3.

   Once a well-formed block has been decrypted, the records from RDATA
   are subjected to record processing.










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7.3.  Record Processing

   In record processing, only the valid records obtained are considered.
   To filter records by validity, the resolver MUST at least check the
   expiration time and the FLAGS field of the respective record.
   Specifically, the resolver MUST disregard expired records.
   Furthermore, SHADOW and SUPPLEMENTAL flags can also exclude records
   from being considered.  If the resolver encounters a record with the
   CRITICAL flag set and does not support the record type the resolution
   MUST be aborted and an error MUST be returned.  The information that
   the critical record could not be processed SHOULD be returned in the
   error description.  The implementation MAY choose not to return the
   reason for the failure, merely complicating troubleshooting for the
   user.

   The next steps depend on the context of the name that is being
   resolved:

   *  Case 1: If the filtered record set consists of a single REDIRECT
      record, the remainder of the name is prepended to the REDIRECT
      data and the recursion is started again from the resulting name.
      Details are described in Section 7.3.1.

   *  Case 2: If the filtered record set consists exclusively of one or
      more GNS2DNS records resolution continues with DNS.  Details are
      described in Section 7.3.2.

   *  Case 3: If the remainder of the name to be resolved is of the
      format "_SERVICE._PROTO" and the record set contains one or more
      matching BOX records, the records in the BOX records are the final
      result and the recursion is concluded as described in
      Section 7.3.3.

   *  Case 4: If the current record set consist of a single delegation
      record, resolution of the remainder of the name is delegated to
      the target zone as described in Section 7.3.4.

   *  Case 5: If the remainder of the name to resolve is empty the
      record set is the final result.  If any NICK records are in the
      final result set, they MUST first be processed according to
      Section 7.3.5.  Otherwise, the record result set is directly
      returned as the final result.

   *  Finally, if none of the above is applicable, resolution fails and
      the resolver MUST return an empty record set.






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7.3.1.  REDIRECT

   If the remaining name is empty and the desired record type is
   REDIRECT, in which case the resolution concludes with the REDIRECT
   record.  If the rightmost label of the redirect name is the extension
   label (U+002B, "+"), resolution continues in GNS with the new name in
   the current zone.  Otherwise, the resulting name is resolved via the
   default operating system name resolution process.  This can in turn
   trigger a GNS name resolution process depending on the system
   configuration.  In case resolution continues in DNS, the name MUST
   first be converted to an IDNA compliant representation [RFC5890].

   In order to prevent infinite loops, the resolver MUST implement loop
   detection or limit the number of recursive resolution steps.  The
   loop detection MUST be effective even if a REDIRECT found in GNS
   triggers subsequent GNS lookups via the default operating system name
   resolution process.

7.3.2.  GNS2DNS

   When a resolver encounters one or more GNS2DNS records and the
   remaining name is empty and the desired record type is GNS2DNS, the
   GNS2DNS records are returned.

   Otherwise, it is expected that the resolver first resolves the IP
   addresses of the specified DNS name servers.  The DNS name MUST be
   converted to an IDNA compliant representation [RFC5890] for
   resolution in DNS.  GNS2DNS records MAY contain numeric IPv4 or IPv6
   addresses, allowing the resolver to skip this step.  The DNS server
   names might themselves be names in GNS or DNS.  If the rightmost
   label of the DNS server name is the extension label (U+002B, "+"),
   the rest of the name is to be interpreted relative to the zone of the
   GNS2DNS record.  If the DNS server name ends in a label
   representation of a zone key, the DNS server name is to be resolved
   against the GNS zone zk.

   Multiple GNS2DNS records can be stored under the same label, in which
   case the resolver MUST try all of them.  The resolver MAY try them in
   any order or even in parallel.  If multiple GNS2DNS records are
   present, the DNS name MUST be identical for all of them.  Otherwise,
   it is not clear which name the resolver is supposed to follow.  If
   different DNS names are present the resolution fails and an
   appropriate error is SHOULD be returned to the application.

   If there are DNSSEC DS records or any other records used to secure
   the connection with the DNS servers stored under the label, the DNS
   resolver SHOULD use them to secure the connection with the DNS
   server.



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   Once the IP addresses of the DNS servers have been determined, the
   DNS name from the GNS2DNS record is appended to the remainder of the
   name to be resolved, and resolved by querying the DNS name server(s).
   The synthesized name has to be converted to an IDNA compliant
   representation [RFC5890] for resolution in DNS.  If such a conversion
   is not possible, the resolution MUST be aborted and an error MUST be
   returned.  The information that the critical record could not be
   processed SHOULD be returned in the error description.  The
   implementation MAY choose not to return the reason for the failure,
   merely complicating troubleshooting for the user.

   As the DNS servers specified are possibly authoritative DNS servers,
   the GNS resolver MUST support recursive DNS resolution and MUST NOT
   delegate this to the authoritative DNS servers.  The first successful
   recursive name resolution result is returned to the application.  In
   addition, the resolver SHOULD return the queried DNS name as a
   supplemental LEHO record (see Section 5.3.1) with a relative
   expiration time of one hour.

   Once the transition from GNS into DNS is made through a GNS2DNS
   record, there is no "going back".  The (possibly recursive)
   resolution of the DNS name MUST NOT delegate back into GNS and should
   only follow the DNS specifications.  For example, names contained in
   DNS CNAME records MUST NOT be interpreted by resolvers that support
   both DNS and GNS as GNS names.

   GNS resolvers SHOULD offer a configuration option to disable DNS
   processing to avoid information leakage and provide a consistent
   security profile for all name resolutions.  Such resolvers would
   return an empty record set upon encountering a GNS2DNS record during
   the recursion.  However, if GNS2DNS records are encountered in the
   record set for the apex label and a GNS2DNS record is explicitly
   requested by the application, such records MUST still be returned,
   even if DNS support is disabled by the GNS resolver configuration.

7.3.3.  BOX

   When a BOX record is received, a GNS resolver must unbox it if the
   name to be resolved continues with "_SERVICE._PROTO".  Otherwise, the
   BOX record is to be left untouched.  This way, TLSA (and SRV) records
   do not require a separate network request, and TLSA records become
   inseparable from the corresponding address records.









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7.3.4.  Zone Delegation Records

   When the resolver encounters a record of a supported zone delegation
   record type (such as PKEY or EDKEY) and the remainder of the name is
   not empty, resolution continues recursively with the remainder of the
   name in the GNS zone specified in the delegation record.

   Whenever a resolver encounters a new GNS zone, it MUST check against
   the local revocation list (see Section 4.2) whether the respective
   zone key has been revoked.  If the zone key was revoked, the
   resolution MUST fail with an empty result set.

   Implementations MUST NOT allow multiple different zone delegations
   under a single label (except if some are shadow records).
   Implementations MAY support any subset of ztypes.  Implementations
   MUST NOT process zone delegation records stored under the apex label
   ("@").  If a zone delegation record is encountered under the apex
   label, resolution fails and an error MUST be returned.  The
   implementation MAY choose not to return the reason for the failure,
   merely impacting troubleshooting information for the user.

   If the remainder of the name to resolve is empty and a record set was
   received containing only a single delegation record, the recursion is
   continued with the record value as authoritative zone and the apex
   label "@" as remaining name.  Except in the case where the desired
   record type as specified by the application is equal to the ztype, in
   which case the delegation record is returned.

7.3.5.  NICK

   NICK records are only relevant to the recursive resolver if the
   record set in question is the final result which is to be returned to
   the application.  The encountered NICK records can either be
   supplemental (see Section 5) or non-supplemental.  If the NICK record
   is supplemental, the resolver only returns the record set if one of
   the non-supplemental records matches the queried record type.  It is
   possible that one record set contains both supplemental and non-
   supplemental NICK records.

   The differentiation between a supplemental and non-supplemental NICK
   record allows the application to match the record to the
   authoritative zone.  Consider the following example:

   Query: alice.example.gns.alt (type=A)
   Result:
   A: 192.0.2.1
   NICK: eve (non-supplemental)




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   In this example, the returned NICK record is non-supplemental.  For
   the application, this means that the NICK belongs to the zone
   "alice.example.gns.alt" and is published under the apex label along
   with an A record.  The NICK record is interpreted as: The zone
   defined by "alice.example.gns.alt" wants to be referred to as "eve".
   In contrast, consider the following:

   Query: alice.example.gns.alt (type=AAAA)
   Result:
   AAAA: 2001:DB8::1
   NICK: john (supplemental)

   In this case, the NICK record is marked as supplemental.  This means
   that the NICK record belongs to the zone "example.gns.alt" and is
   published under the label "alice" along with an AAAA record.  Here,
   the NICK record should be interpreted as: The zone defined by
   "example.gns.alt" wants to be referred to as "john".  This
   distinction is likely useful for other records published as
   supplemental.

8.  Internationalization and Character Encoding

   All names in GNS are encoded in UTF-8 [RFC3629].  Labels MUST be
   canonicalized using Normalization Form C (NFC) [Unicode-UAX15].  This
   does not include any DNS names found in DNS records, such as CNAME
   record data, which is internationalized through the IDNA
   specifications [RFC5890].

9.  Security and Privacy Considerations

9.1.  Availability

   In order to ensure availability of records beyond their absolute
   expiration times, implementations MAY allow to locally define
   relative expiration time values of records.  Records can then be
   published recurringly with updated absolute expiration times by the
   implementation.

   Implementations MAY allow users to manage private records in their
   zones that are not published in the storage.  Private records are
   considered just like regular records when resolving labels in local
   zones, but their data is completely unavailable to non-local users.









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9.2.  Agility

   The security of cryptographic systems depends on both the strength of
   the cryptographic algorithms chosen and the strength of the keys used
   with those algorithms.  The security also depends on the engineering
   of the protocol used by the system to ensure that there are no non-
   cryptographic ways to bypass the security of the overall system.
   This is why developers of applications managing GNS zones SHOULD
   select a default ztype considered secure at the time of releasing the
   software.  For applications targeting end users that are not expected
   to understand cryptography, the application developer MUST NOT leave
   the ztype selection of new zones to end users.

   This document concerns itself with the selection of cryptographic
   algorithms used in GNS.  The algorithms identified in this document
   are not known to be broken (in the cryptographic sense) at the
   current time, and cryptographic research so far leads us to believe
   that they are likely to remain secure into the foreseeable future.
   However, this is not necessarily forever, and it is expected that new
   revisions of this document will be issued from time to time to
   reflect the current best practices in this area.

   In terms of crypto-agility, whenever the need for an updated
   cryptographic scheme arises to, for example, replace ECDSA over
   Ed25519 for PKEY records, it can simply be introduced through a new
   record type.  Zone administrators can then replace the delegation
   record type for future records.  The old record type remains and
   zones can iteratively migrate to the updated zone keys.  To ensure
   that implementations correctly generate an error message when
   encountering a ztype that they do not support, current and future
   delegation records must always have the CRITICAL flag set.

9.3.  Cryptography

   The following considerations provide background on the design choices
   of the ztypes specified in this document.  When specifying new ztypes
   as per Section 4, the same considerations apply.














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   GNS PKEY zone keys use ECDSA over Ed25519.  This is an unconventional
   choice, as ECDSA is usually used with other curves.  However,
   standardized ECDSA curves are problematic for a range of reasons
   described in the Curve25519 and EdDSA papers [ed25519].  Using EdDSA
   directly is also not possible, as a hash function is used on the
   private key which destroys the linearity that the key blinding in GNS
   depends upon.  We are not aware of anyone suggesting that using
   Ed25519 instead of another common curve of similar size would lower
   the security of ECDSA.  GNS uses 256-bit curves because that way the
   encoded (public) keys fit into a single DNS label, which is good for
   usability.

   In order to ensure ciphertext indistinguishability, care must be
   taken with respect to the initialization vector in the counter block.
   In our design, the IV always includes the expiration time of the
   record block.  When applications store records with relative
   expiration times, monotonicity is implicitly ensured because each
   time a block is published into the storage, its IV is unique as the
   expiration time is calculated dynamically and increases monotonically
   with the system time.  Still, an implementation MUST ensure that when
   relative expiration times are decreased, the expiration time of the
   next record block MUST be after the last published block.  For
   records where an absolute expiration time is used, the implementation
   MUST ensure that the expiration time is always increased when the
   record data changes.  For example, the expiration time on the wire
   could be increased by a single microsecond even if the user did not
   request a change.  In case of deletion of all resource records under
   a label, the implementation MUST keep track of the last absolute
   expiration time of the last published resource block.
   Implementations MAY define and use a special record type as a
   tombstone that preserves the last absolute expiration time, but then
   MUST take care to not publish a block with such a tombstone record.
   When new records are added under this label later, the implementation
   MUST ensure that the expiration times are after the last published
   block.  Finally, in order to ensure monotonically increasing
   expiration times the implementation MUST keep a local record of the
   last time obtained from the system clock, so as to construct a
   monotonic clock in case the system clock jumps backwards.

9.4.  Abuse Mitigation

   GNS names are UTF-8 strings.  Consequently, GNS faces similar issues
   with respect to name spoofing as DNS does for internationalized
   domain names.  In DNS, attackers can register similar sounding or
   looking names (see above) in order to execute phishing attacks.  GNS
   zone administrators must take into account this attack vector and
   incorporate rules in order to mitigate it.




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   Further, DNS can be used to combat illegal content on the Internet by
   having the respective domains seized by authorities.  However, the
   same mechanisms can also be abused in order to impose state
   censorship.  Avoiding that possibility is one of the motivations
   behind GNS.  In GNS, TLDs are not enumerable.  By design, the start
   zone of the resolver is defined locally and hence such a seizure is
   difficult and ineffective in GNS.

9.5.  Zone Management

   In GNS, zone administrators need to manage and protect their zone
   keys.  Once a private zone key is lost, it cannot be recovered and
   the zone revocation message cannot be computed anymore.  Revocation
   messages can be pre-calculated if revocation is required in case a
   private zone key is lost.  Zone administrators, and for GNS this
   includes end-users, are required to responsibly and diligently
   protect their cryptographic keys.  GNS supports signing records in
   advance ("offline") in order to support processes (such as air gaps)
   which aim to protect private keys.

   Similarly, users are required to manage their local start zone
   configuration.  In order to ensure integrity and availability or
   names, users must ensure that their local start zone information is
   not compromised or outdated.  It can be expected that the processing
   of zone revocations and an initial start zone is provided with a GNS
   implementation ("drop shipping").  Shipping an initial start zone
   configuration effectively establishes a root zone.  Extension and
   customization of the zone is at the full discretion of the user.

   While implementations following this specification will be
   interoperable, if two implementations connect to different remote
   storages they are mutually unreachable.  This can lead to a state
   where a record exists in the global namespace for a particular name,
   but the implementation is not communicating with the remote storage
   that contains the respective block and is hence unable to resolve it.
   This situation is similar to a split-horizon DNS configuration.
   Which remote storages are implemented usually depends on the
   application it is built for.  The remote storage used will most
   likely depend on the specific application context using GNS
   resolution.  For example, one application is the resolution of hidden
   services within the Tor network, which would suggest using Tor
   routers for remote storage.  Implementations of "aggregated" remote
   storages are conceivable, but are expected to be the exception.








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9.6.  DHTs as Remote Storage

   This document does not specify the properties of the underlying
   remote storage which is required by any GNS implementation.  It is
   important to note that the properties of the underlying remote
   storage are directly inherited by the GNS implementation.  This
   includes both security as well as other non-functional properties
   such as scalability and performance.  Implementers should take great
   care when selecting or implementing a DHT for use as remote storage
   in a GNS implementation.  DHTs with reasonable security and
   performance properties exist [R5N].  It should also be taken into
   consideration that GNS implementations which build upon different DHT
   overlays are unlikely to be interoperable with each other.

9.7.  Revocations

   Zone administrators are advised to pre-generate zone revocations and
   to securely store the revocation information in case the zone key is
   lost, compromised or replaced in the future.  Pre-calculated
   revocations can cease to be valid due to expirations or protocol
   changes such as epoch adjustments.  Consequently, implementers and
   users must take precautions in order to manage revocations
   accordingly.

   Revocation payloads do not include a 'new' key for key replacement.
   Inclusion of such a key would have two major disadvantages:

   1.  If a revocation is published after a private key was compromised,
       allowing key replacement would be dangerous: if an adversary took
       over the private key, the adversary could then broadcast a
       revocation with a key replacement.  For the replacement, the
       compromised owner would have no chance to issue a revocation.
       Thus, allowing a revocation message to replace a private key
       makes dealing with key compromise situations worse.

   2.  Sometimes, key revocations are used with the objective of
       changing cryptosystems.  Migration to another cryptosystem by
       replacing keys via a revocation message would only be secure as
       long as both cryptosystems are still secure against forgery.
       Such a planned, non-emergency migration to another cryptosystem
       should be done by running zones for both cipher systems in
       parallel for a while.  The migration would conclude by revoking
       the legacy zone key only once it is deemed no longer secure, and
       hopefully after most users have migrated to the replacement.







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9.8.  Zone Privacy

   GNS does not support authenticated denial of existence of names
   within a zone.  Record data is published in encrypted form using keys
   derived from the zone key and record label.  Zone administrators
   should carefully consider if a label and zone key are public, or if
   one or both of these should be used as a shared secret to restrict
   access to the corresponding record data.  Unlike public zone keys,
   low-entropy labels can be guessed by an attacker.  If an attacker
   knows the public zone key, the use of well known or guessable labels
   effectively threatens the disclosure of the corresponding records.

   It should be noted that the guessing attack on labels only applies if
   the zone key is somehow disclosed to the adversary.  GNS itself does
   not disclose it during a lookup or when resource records are
   published (as only the blinded zone keys are used on the network).
   However, zone keys do become public during revocation.

   It is thus RECOMMENDED to use a label with sufficient entropy to
   prevent guessing attacks if any data in a resource record set is
   sensitive.

9.9.  Zone Governance

   While DNS is distributed, in practice it relies on centralized,
   trusted registrars to provide globally unique names.  As the
   awareness of the central role DNS plays on the Internet rises,
   various institutions are using their power (including legal means) to
   engage in attacks on the DNS, thus threatening the global
   availability and integrity of information on the Internet.  While a
   wider discussion of this issue is out of scope for this document,
   analyses and investigations can be found in recent academic research
   works including [SecureNS].

   GNS is designed to provide a secure, privacy-enhancing alternative to
   the DNS name resolution protocol, especially when censorship or
   manipulation is encountered.  In particular, it directly addresses
   concerns in DNS with respect to query privacy.  However, depending on
   the governance of the root zone, any deployment will likely suffer
   from the issues of a "Single Hierarchy with a Centrally Controlled
   Root" and "Distribution and Management of Root Servers" as raised in
   [RFC8324].  In DNS, those issues are a direct result from the
   centralized root zone governance at the Internet Corporation for
   Assigned Names and Numbers (ICANN) which allows it to provide
   globally unique names.






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   In GNS, start zones give users local authority over their preferred
   root zone governance.  It enables users to replace or enhance a
   trusted root zone configuration provided by a third party (e.g. the
   implementer or a multi-stakeholder governance body like ICANN) with
   secure delegation of authority using local petnames while operating
   under a very strong adversary model.  In combination with zTLDs, this
   provides users of GNS with a global, secure and memorable mapping
   without a trusted authority.

   Any GNS implementation MAY provide a default governance model in the
   form of an initial start zone mapping.

9.10.  Namespace Ambiguity

   Technically, the GNS protocol can be used to resolve names in the
   namespace of the global DNS.  However, this would require the
   respective governance bodies and stakeholders (e.g.  IETF and ICANN)
   to standardize the use of GNS for this particular use case.

   However, this capability implies that GNS names may be
   indistinguishable from DNS names in their respective common display
   format [RFC8499] or other special-use domain names [RFC6761] if a
   local start zone configuration maps suffixes from the global DNS to
   GNS zones.  For applications, it is then ambiguous which name system
   should be used in order to resolve a given name.  This poses a risk
   when trying to resolve a name through DNS when it is actually a GNS
   name as discussed in [RFC8244].  In such a case, the GNS name is
   likely to be leaked as part of the DNS resolution.

   In order to prevent disclosure of queried GNS names it is RECOMMENDED
   that GNS-aware applications try to resolve a given name in GNS before
   any other method taking into account potential suffix-to-zone
   mappings and zTLDs.  Suffix-to-zone mappings are expected to be
   configured by the user or local administrator and as such the
   resolution in GNS is in line with user expectations even if the name
   could also be resolved through DNS.  If no suffix-to-zone mapping for
   the name exists and no zTLD is found, resolution MAY continue with
   other methods such as DNS.  If a suffix-to-zone mapping for the name
   exists or the name ends with a zTLD, it MUST be resolved using GNS
   and resolution MUST NOT continue by any other means independent of
   the GNS resolution result.

   Mechanisms such as the Name Service Switch (NSS) of Unix-like
   operating systems are an example of how such a resolution process can
   be implemented and used.  It allows system administrators to
   configure host name resolution precedence and is integrated with the
   system resolver implementation.




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   For use cases where GNS names may be confused with names of other
   name resolution mechanisms (in particular DNS), the ".gns.alt" domain
   SHOULD be used.  For use cases like implementing sinkholes to block
   malware sites or serving DNS domains via GNS to bypass censorship,
   GNS MAY be deliberately used in ways that interfere with resolution
   of another name system.

10.  GANA Considerations

   GANA has assigned signature purposes in its "GNUnet Signature
   Purpose" registry as listed in Figure 24.

   Purpose | Name            | References | Comment
   --------+-----------------+------------+--------------------------
     3     | GNS_REVOCATION  | [This.I-D] | GNS zone key revocation
    15     | GNS_RECORD_SIGN | [This.I-D] | GNS record set signature

     Figure 24: Requested Changes in the GANA GNUnet Signature Purpose
                                 Registry.

10.1.  GNS Record Types Registry

   GANA [GANA] manages the "GNS Record Types" registry.  Each entry has
   the following format:

   *  Name: The name of the record type (case-insensitive ASCII string,
      restricted to alphanumeric characters).  For zone delegation
      records, the assigned number represents the ztype value of the
      zone.

   *  Number: 32-bit, above 65535

   *  Comment: Optionally, a brief English text describing the purpose
      of the record type (in UTF-8)

   *  Contact: Optionally, the contact information of a person to
      contact for further information.

   *  References: Optionally, references describing the record type
      (such as an RFC).

   The registration policy for this registry is "First Come First
   Served".  This policy is modeled on that described in [RFC8126], and
   describes the actions taken by GANA:







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   Adding new entries is possible after review by any authorized GANA
   contributor, using a first-come-first-served policy for unique name
   allocation.  Reviewers are responsible to ensure that the chosen
   "Name" is appropriate for the record type.  The registry will define
   a unique number for the entry.

   Authorized GANA contributors for review of new entries are reachable
   at gns-registry@gnunet.org.

   Any request MUST contain a unique name and a point of contact.  The
   contact information MAY be added to the registry given the consent of
   the requester.  The request MAY optionally also contain relevant
   references as well as a descriptive comment as defined above.

   GANA has assigned numbers for the record types defined in this
   specification in the "GNU Name System Record Types" registry as
   listed in Figure 25.

   Number | Name    | Contact | References | Comment
   -------+---------+---------+------------+-------------------------
   65536  | PKEY    | (*)     | [This.I-D] | GNS zone delegation (PKEY)
   65537  | NICK    | (*)     | [This.I-D] | GNS zone nickname
   65538  | LEHO    | (*)     | [This.I-D] | GNS legacy hostname
   65540  | GNS2DNS | (*)     | [This.I-D] | Delegation to DNS
   65541  | BOX     | (*)     | [This.I-D] | Boxed records
   65551  | REDIRECT| (*)     | [This.I-D] | Redirection record.
   65556  | EDKEY   | (*)     | [This.I-D] | GNS zone delegation (EDKEY)

   (*): gns-registry@gnunet.org

               Figure 25: The GANA Resource Record Registry.

10.2.  .alt Subdomains Registry

   GANA [GANA] manages the ".alt Subdomains" registry.  Each entry has
   the following format:

   *  Label: The label of the subdomain (in DNS LDH format as defined in
      Section 2.3.1 of [RFC5890]).

   *  Comment: Optionally, a brief English text describing the purpose
      of the subdomain (in UTF-8)

   *  Contact: Optionally, the contact information of a person to
      contact for further information.

   *  References: Optionally, references describing the record type
      (such as an RFC).



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   The registration policy for this registry is "First Come First
   Served".  This policy is modeled on that described in [RFC8126], and
   describes the actions taken by GANA:

   Adding new entries is possible after review by any authorized GANA
   contributor, using a first-come-first-served policy for unique
   subdomain allocation.  Reviewers are responsible to ensure that the
   chosen "Subdomain" is appropriate for the purpose.

   Authorized GANA contributors for review of new entries are reachable
   at alt-registry@gnunet.org.

   Any request MUST contain a unique subdomain and a point of contact.
   The contact information MAY be added to the registry given the
   consent of the requester.  The request MAY optionally also contain
   relevant references as well as a descriptive comment as defined
   above.

   GANA has assigned the subdomain defined in this specification in the
   ".alt subdomains" registry as listed in Figure 26.

   Subdomain | Contact | References | Comment
   ----------+---------+------------+----------------------------
   gns       | (*)     | [This.I-D] | The .alt subdomain for GNS.

   (*): alt-registry@gnunet.org

               Figure 26: The GANA .alt Subdomains Registry.

11.  IANA Considerations

   This document makes no requests for IANA action.  This section may be
   removed on publication as an RFC.

12.  Implementation and Deployment Status

   There are two implementations conforming to this specification
   written in C and Go, respectively.  The C implementation as part of
   GNUnet [GNUnetGNS] represents the original and reference
   implementation.  The Go implementation [GoGNS] demonstrates how two
   implementations of GNS are interoperable if they are built on top of
   the same underlying DHT storage.









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   Currently, the GNUnet peer-to-peer network [GNUnet] is an active
   deployment of GNS on top of its [R5N] DHT.  The [GoGNS]
   implementation uses this deployment by building on top of the GNUnet
   DHT services available on any GNUnet peer.  It shows how GNS
   implementations can attach to this existing deployment and
   participate in name resolution as well as zone publication.

   The self-sovereign identity system re:claimID [reclaim] is using GNS
   in order to selectively share identity attributes and attestations
   with third parties.

   The Ascension tool [Ascension] facilitates the migration of DNS zones
   to GNS zones by translating information retrieved from a DNS zone
   transfer into a GNS zone.

13.  Acknowledgements

   The authors thank all reviewers for their comments.  In particular,
   we thank D.  J.  Bernstein, S.  Bortzmeyer, A.  Farrel, E.  Lear and
   R.  Salz for their insightful and detailed technical reviews.  We
   thank J.  Yao and J.  Klensin for the internationalization reviews.
   We thank NLnet and NGI DISCOVERY for funding work on the GNU Name
   System.

14.  Normative References

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <https://www.rfc-editor.org/info/rfc1034>.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/info/rfc1035>.

   [RFC2782]  Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
              specifying the location of services (DNS SRV)", RFC 2782,
              DOI 10.17487/RFC2782, February 2000,
              <https://www.rfc-editor.org/info/rfc2782>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3629]  Yergeau, F., "UTF-8, a transformation format of ISO
              10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
              2003, <https://www.rfc-editor.org/info/rfc3629>.




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   [RFC3686]  Housley, R., "Using Advanced Encryption Standard (AES)
              Counter Mode With IPsec Encapsulating Security Payload
              (ESP)", RFC 3686, DOI 10.17487/RFC3686, January 2004,
              <https://www.rfc-editor.org/info/rfc3686>.

   [RFC3826]  Blumenthal, U., Maino, F., and K. McCloghrie, "The
              Advanced Encryption Standard (AES) Cipher Algorithm in the
              SNMP User-based Security Model", RFC 3826,
              DOI 10.17487/RFC3826, June 2004,
              <https://www.rfc-editor.org/info/rfc3826>.

   [RFC5237]  Arkko, J. and S. Bradner, "IANA Allocation Guidelines for
              the Protocol Field", BCP 37, RFC 5237,
              DOI 10.17487/RFC5237, February 2008,
              <https://www.rfc-editor.org/info/rfc5237>.

   [RFC5869]  Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-Expand
              Key Derivation Function (HKDF)", RFC 5869,
              DOI 10.17487/RFC5869, May 2010,
              <https://www.rfc-editor.org/info/rfc5869>.

   [RFC5890]  Klensin, J., "Internationalized Domain Names for
              Applications (IDNA): Definitions and Document Framework",
              RFC 5890, DOI 10.17487/RFC5890, August 2010,
              <https://www.rfc-editor.org/info/rfc5890>.

   [RFC5895]  Resnick, P. and P. Hoffman, "Mapping Characters for
              Internationalized Domain Names in Applications (IDNA)
              2008", RFC 5895, DOI 10.17487/RFC5895, September 2010,
              <https://www.rfc-editor.org/info/rfc5895>.

   [RFC6234]  Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
              (SHA and SHA-based HMAC and HKDF)", RFC 6234,
              DOI 10.17487/RFC6234, May 2011,
              <https://www.rfc-editor.org/info/rfc6234>.

   [RFC6895]  Eastlake 3rd, D., "Domain Name System (DNS) IANA
              Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,
              April 2013, <https://www.rfc-editor.org/info/rfc6895>.

   [RFC6979]  Pornin, T., "Deterministic Usage of the Digital Signature
              Algorithm (DSA) and Elliptic Curve Digital Signature
              Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979, August
              2013, <https://www.rfc-editor.org/info/rfc6979>.

   [RFC7748]  Langley, A., Hamburg, M., and S. Turner, "Elliptic Curves
              for Security", RFC 7748, DOI 10.17487/RFC7748, January
              2016, <https://www.rfc-editor.org/info/rfc7748>.



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   [RFC8032]  Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
              Signature Algorithm (EdDSA)", RFC 8032,
              DOI 10.17487/RFC8032, January 2017,
              <https://www.rfc-editor.org/info/rfc8032>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8499]  Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
              Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
              January 2019, <https://www.rfc-editor.org/info/rfc8499>.

   [RFC9106]  Biryukov, A., Dinu, D., Khovratovich, D., and S.
              Josefsson, "Argon2 Memory-Hard Function for Password
              Hashing and Proof-of-Work Applications", RFC 9106,
              DOI 10.17487/RFC9106, September 2021,
              <https://www.rfc-editor.org/info/rfc9106>.

   [GANA]     GNUnet e.V., "GNUnet Assigned Numbers Authority (GANA)",
              November 2022, <https://gana.gnunet.org/>.

   [MODES]    Dworkin, M., "Recommendation for Block Cipher Modes of
              Operation: Methods and Techniques", December 2001,
              <https://doi.org/10.6028/NIST.SP.800-38A>.

   [CrockfordB32]
              Douglas, D., "Base32", March 2019,
              <https://www.crockford.com/base32.html>.

   [XSalsa20] Bernstein, D., "Extending the Salsa20 nonce", 2011,
              <https://cr.yp.to/snuffle/xsalsa-20110204.pdf>.

   [Unicode-UAX15]
              The Unicode Consortium, "Unicode Standard Annex #15:
              Unicode Normalization Forms, Revision 31", September 2009,
              <http://www.unicode.org/reports/tr15/tr15-31.html>.

   [Unicode-UTS46]
              The Unicode Consortium, "Unicode Technical Standard #46:
              Unicode IDNA Compatibility Processing, Revision 27",
              August 2021, <https://www.unicode.org/reports/tr46>.




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15.  Informative References

   [RFC1928]  Leech, M., Ganis, M., Lee, Y., Kuris, R., Koblas, D., and
              L. Jones, "SOCKS Protocol Version 5", RFC 1928,
              DOI 10.17487/RFC1928, March 1996,
              <https://www.rfc-editor.org/info/rfc1928>.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements",
              RFC 4033, DOI 10.17487/RFC4033, March 2005,
              <https://www.rfc-editor.org/info/rfc4033>.

   [RFC6066]  Eastlake 3rd, D., "Transport Layer Security (TLS)
              Extensions: Extension Definitions", RFC 6066,
              DOI 10.17487/RFC6066, January 2011,
              <https://www.rfc-editor.org/info/rfc6066>.

   [RFC7363]  Maenpaa, J. and G. Camarillo, "Self-Tuning Distributed
              Hash Table (DHT) for REsource LOcation And Discovery
              (RELOAD)", RFC 7363, DOI 10.17487/RFC7363, September 2014,
              <https://www.rfc-editor.org/info/rfc7363>.

   [RFC8324]  Klensin, J., "DNS Privacy, Authorization, Special Uses,
              Encoding, Characters, Matching, and Root Structure: Time
              for Another Look?", RFC 8324, DOI 10.17487/RFC8324,
              February 2018, <https://www.rfc-editor.org/info/rfc8324>.

   [RFC8806]  Kumari, W. and P. Hoffman, "Running a Root Server Local to
              a Resolver", RFC 8806, DOI 10.17487/RFC8806, June 2020,
              <https://www.rfc-editor.org/info/rfc8806>.

   [RFC6761]  Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
              RFC 6761, DOI 10.17487/RFC6761, February 2013,
              <https://www.rfc-editor.org/info/rfc6761>.

   [RFC8244]  Lemon, T., Droms, R., and W. Kumari, "Special-Use Domain
              Names Problem Statement", RFC 8244, DOI 10.17487/RFC8244,
              October 2017, <https://www.rfc-editor.org/info/rfc8244>.

   [I-D.ietf-dnsop-alt-tld]
              Kumari, W. A. and P. E. Hoffman, "The ALT Special Use Top
              Level Domain", Work in Progress, Internet-Draft, draft-
              ietf-dnsop-alt-tld-25, 4 May 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-dnsop-
              alt-tld-25>.






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   [Tor224]   Goulet, D., Kadianakis, G., and N. Mathewson, "Next-
              Generation Hidden Services in Tor", November 2013,
              <https://gitweb.torproject.org/torspec.git/tree/
              proposals/224-rend-spec-ng.txt#n2135>.

   [SDSI]     Rivest, R. and B. Lampson, "SDSI - A Simple Distributed
              Security Infrastructure", April 1996,
              <http://people.csail.mit.edu/rivest/Sdsi10.ps>.

   [Kademlia] Maymounkov, P. and D. Mazieres, "Kademlia: A peer-to-peer
              information system based on the xor metric.", 2002,
              <http://css.csail.mit.edu/6.824/2014/papers/kademlia.pdf>.

   [ed25519]  Bernstein, D., Duif, N., Lange, T., Schwabe, P., and B.
              Yang, "High-Speed High-Security Signatures", 2011,
              <https://ed25519.cr.yp.to/ed25519-20110926.pdf>.

   [GNS]      Wachs, M., Schanzenbach, M., and C. Grothoff, "A
              Censorship-Resistant, Privacy-Enhancing and Fully
              Decentralized Name System", 2014,
              <https://sci-hub.st/10.1007/978-3-319-12280-9_9>.

   [R5N]      Evans, N. S. and C. Grothoff, "R5N: Randomized recursive
              routing for restricted-route networks", 2011,
              <https://sci-hub.st/10.1109/ICNSS.2011.6060022>.

   [SecureNS] Grothoff, C., Wachs, M., Ermert, M., and J. Appelbaum,
              "Towards secure name resolution on the Internet", 2018,
              <https://sci-hub.st/https://doi.org/10.1016/
              j.cose.2018.01.018>.

   [GNUnetGNS]
              GNUnet e.V., "The GNUnet GNS Implementation",
              <https://git.gnunet.org/gnunet.git/tree/src/gns>.

   [Ascension]
              GNUnet e.V., "The Ascension Implementation",
              <https://git.gnunet.org/ascension.git>.

   [GNUnet]   GNUnet e.V., "The GNUnet Project", <https://gnunet.org>.

   [reclaim]  GNUnet e.V., "re:claimID", <https://reclaim.gnunet.org>.

   [GoGNS]    Fix, B., "The Go GNS Implementation",
              <https://github.com/bfix/gnunet-
              go/tree/master/src/gnunet/service/gns>.





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   [nsswitch] GNU Project, "System Databases and Name Service Switch",
              <https://www.gnu.org/software/libc/manual/html_node/Name-
              Service-Switch.html>.

Appendix A.  Usage and Migration

   This section outlines a number of specific use cases which may help
   readers of the technical specification to understand the protocol
   better.  The considerations below are not meant to be normative for
   the GNS protocol in any way.  Instead, they are provided in order to
   give context and to provide some background on what the intended use
   of the protocol is by its designers.  Further, this section contains
   pointers to migration paths.

A.1.  Zone Dissemination

   In order to become a zone owner, it is sufficient to generate a zone
   key and a corresponding secret key using a GNS implementation.  At
   this point, the zone owner can manage GNS resource records in a local
   zone database.  The resource records can then be published by a GNS
   implementation as defined in Section 6.  For other users to resolve
   the resource records, respective zone information must be
   disseminated first.  The zone owner may decide to make the zone key
   and labels known to a selected set of users only or to make this
   information available to the general public.

   Sharing zone information directly with specific users not only allows
   to potentially preserve zone and record privacy, but also allows the
   zone owner and the user to establish strong trust relationships.  For
   example, a bank may send a customer letter with a QR code which
   contains the GNS zone of the bank.  This allows the user to scan the
   QR code and establish a strong link to the zone of the bank and with
   it, for example, the IP address of the online banking web site.

   Most Internet services likely want to make their zones available to
   the general public as efficiently as possible.  First, it is
   reasonable to assume that zones which are commanding high levels of
   reputation and trust are likely included in the default suffix-to-
   zone mappings of implementations.  Hence dissemination of a zone
   through delegation under such zones can be a viable path in order to
   disseminate a zone publicly.  For example, it is conceivable that
   organizations such as ICANN or country-code top-level domain
   registrars also manage GNS zones and offer registration or delegation
   services.

   Following best practices in particularly those relating to security
   and abuse mitigation are methods which allow zone owners and aspiring
   registrars to gain a good reputation and eventually trust.  This



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   includes, of course, diligent protection of private zone key
   material.  Formalizing such best practices is out of scope of this
   specification and should be addressed in a separate document and take
   Section 9 into account.

A.2.  Start Zone Configuration

   A user is expected to install a GNS implementation if it is not
   already provided through other means such as the operating system or
   the browser.  It is likely that the implementation ships with a
   default start zone configuration.  This means that the user is able
   to resolve GNS names ending on a zTLD or ending on any suffix-to-name
   mapping that is part of the default start zone configuration.  At
   this point the user may delete or otherwise modify the
   implementation's default configuration:

   Deletion of suffix-to-zone mappings may become necessary of the zone
   owner referenced by the mapping has lost the trust of the user.  For
   example, this could be due to lax registration policies resulting in
   phishing activities.  Modification and addition of new mappings are
   means to heal the namespace perforation which would occur in the case
   of a deletion or to simply establish a strong direct trust
   relationship.  However, this requires the user's knowledge of the
   respective zone keys.  This information must be retrieved out of
   band, as illustrated in Appendix A.1: A bank may send the user a
   letter with a QR code which contains the GNS zone of the bank.  The
   user scans the QR code and adds a new suffix-to-name mapping using a
   chosen local name for his bank.  Other examples include scanning zone
   information off the device of a friend, from a storefront, or an
   advertisement.  The level of trust in the respective zone is
   contextual and likely varies from user to user.  Trust in a zone
   provided through a letter from a bank which may also include a credit
   card is certainly different from a zone found on a random
   advertisement in the streets.  However, this trust is immediately
   tangible to the user and can be reflected in the local naming as
   well.

   User clients should facilitate the modification of the start zone
   configuration, for example by providing a QR code reader or other
   import mechanisms.  Implementations are ideally implemented according
   to best practices and addressing applicable points from Section 9.
   Formalizing such best practices is out of scope of this
   specification.








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A.3.  Globally Unique Names and the Web

   HTTP virtual hosting and TLS Server Name Indication are common use
   cases on the Web.  HTTP clients supply a DNS name in the HTTP "Host"-
   header or as part of the TLS handshake, respectively.  This allows
   the HTTP server to serve the indicated virtual host with a matching
   TLS certificate.  The global uniqueness of DNS names are a
   prerequisite of those use cases.

   Not all GNS names are globally unique.  But, any resource record in
   GNS can be represented as a concatenation of of a GNS label and the
   zTLD of the zone.  While not human-readable, this globally unique GNS
   name can be leveraged in order to facilitate the same use cases.
   Consider the GNS name "www.example.gns" entered in a GNS-aware HTTP
   client.  At first, "www.example.gns" is resolved using GNS yielding a
   record set.  Then, the HTTP client determines the virtual host as
   follows:

   If there is a LEHO record (Section 5.3.1) containing
   "www.example.com" in the record set, then the HTTP client uses this
   as the value of the "Host"-header field of the HTTP request:

   GET / HTTP/1.1
   Host: www.example.com

   If there is no LEHO record in the record set, then the HTTP client
   tries to find the zone of the record and translates the GNS name into
   a globally unique zTLD-representation before using it in the "Host"-
   header field of the HTTP request:

   GET / HTTP/1.1
   Host: www.000G0037FH3QTBCK15Y8BCCNRVWPV17ZC7TSGB1C9ZG2TPGHZVFV1GMG3W

   In order to determine the canonical representation of the record with
   a zTLD, at most two queries are required: First, it must be checked
   whether "www.example.gns.alt" itself points to a zone delegation
   record which would imply that the record set which was originally
   resolved is published under the apex label.  If it does, the unique
   GNS name is simply the zTLD representation of the delegated zone:

   GET / HTTP/1.1
   Host: 000G0037FH3QTBCK15Y8BCCNRVWPV17ZC7TSGB1C9ZG2TPGHZVFV1GMG3W

   If it does not, the unique GNS name is the concatenation of the label
   "www" and the zTLD representation of the zone as given in the example
   above.  In any case, this representation is globally unique.  As
   such, it can be configured by the HTTP server administrator as a
   virtual host name and respective certificates may be issued.



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   If the HTTP client is a browser, the use of a unique GNS name for
   virtual hosting or TLS SNI does not necessarily have to be shown to
   the user.  For example, the name in the URL bar may remain as
   "www.example.gns.alt" even if the used unique name differs.

A.4.  Migration Paths

   DNS resolution is built into a variety of existing software
   components.  Most significantly operating systems and HTTP clients.
   This section illustrates possible migration paths for both in order
   to enable "legacy" applications to resolve GNS names.

   One way to efficiently facilitate the resolution of GNS names are
   GNS-enabled DNS server implementations.  Local DNS queries are
   thereby either rerouted or explicitly configured to be resolved by a
   "DNS-to-GNS" server that runs locally.  This DNS server tries to
   interpret any incoming query for a name as a GNS resolution request.
   If no start zone can be found for the name and it does not end in a
   zTLD, the server tries to resolve the name in DNS.  Otherwise, the
   name is resolved in GNS.  In the latter case, the resulting record
   set is converted to a DNS answer packet and is returned accordingly.
   An implementation of a DNS-to-GNS server can be found in [GNUnet].

   A similar approach is to use operating systems extensions such as the
   name service switch [nsswitch].  It allows the system administrator
   to configure plugins which are used for hostname resolution.  A GNS
   name service switch plugin can be used in a similar fashion as the
   "DNS-to-GNS" server.  An implementation of a glibc-compatible
   nsswitch plugin for GNS can be found in [GNUnet].

   The methods above are usually also effective for HTTP client
   software.  However, HTTP clients are commonly used in combination
   with TLS.  TLS certificate validation and in particular server name
   indication (SNI) requires additional logic in HTTP clients when GNS
   names are in play (Appendix A.3).  In order to transparently enable
   this functionality for migration purposes, a local GNS-aware SOCKS5
   proxy [RFC1928] can be configured to resolve domain names.  The
   SOCKS5 proxy, similar to the DNS-to-GNS server, is capable of
   resolving both GNS and DNS names.  In the event of a TLS connection
   request with a GNS name, the SOCKS5 proxy can act as a man-in-the-
   middle, terminating the TLS connection and establishing a secure
   connection against the requested host.  In order to establish a
   secure connection, the proxy may use LEHO and TLSA records stored in
   the record set under the GNS name.  The proxy must provide a locally
   trusted certificate for the GNS name to the HTTP client which usually
   requires the generation and configuration of a local trust anchor in
   the browser.  An implementation of this SOCKS5 proxy can be found in
   [GNUnet].



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Appendix B.  Example flows

B.1.  AAAA Example Resolution

                              Local Host             |   Remote
                                                     |   Storage
                                                     |
                                                     |    +---------+
                                                     |   /         /|
                                                     |  +---------+ |
   +-----------+ (1)      +----------+               |  |         | |
   |           |          |          |      (4,6)    |  | Record  | |
   |Application|----------| Resolver |---------------|->| Storage | |
   |           |<---------|          |<--------------|--|         |/
   +-----------+ (8)      +----------+      (5,7)    |  +---------+
                             A                       |
                             |                       |
                       (2,3) |                       |
                             |                       |
                             |                       |
                          +---------+                |
                         /   v     /|                |
                        +---------+ |                |
                        |         | |                |
                        |  Start  | |                |
                        |  Zones  | |                |
                        |         |/                 |
                        +---------+                  |

             Figure 27: Example resolution of an IPv6 address.

   1.  Lookup AAAA record for name: www.example.gnu.gns.alt.

   2.  Determine start zone for www.example.gnu.gns.alt.

   3.  Start zone: zk0 - Remainder: www.example.

   4.  Calculate q0=SHA512(ZKDF(zk0, "example")) and initiate GET(q0).

   5.  Retrieve and decrypt RRBLOCK consisting of a single PKEY record
       containing zk1.

   6.  Calculate q1=SHA512(ZKDF(zk1, "www")) and initiate GET(q1).

   7.  Retrieve RRBLOCK consisting of a single AAAA record containing
       the IPv6 address 2001:db8::1.

   8.  Return record set to application



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B.2.  REDIRECT Example Resolution

                              Local Host              |   Remote
                                                      |   Storage
                                                      |
                                                      |    +---------+
                                                      |   /         /|
                                                      |  +---------+ |
   +-----------+ (1)      +----------+                |  |         | |
   |           |          |          |      (4,6,8)   |  | Record  | |
   |Application|----------| Resolver |----------------|->| Storage | |
   |           |<---------|          |<---------------|--|         |/
   +-----------+ (10)     +----------+      (5,7,9)   |  +---------+
                             A                        |
                             |                        |
                       (2,3) |                        |
                             |                        |
                             |                        |
                          +---------+                 |
                         /   v     /|                 |
                        +---------+ |                 |
                        |         | |                 |
                        |  Start  | |                 |
                        |  Zones  | |                 |
                        |         |/                  |
                        +---------+                   |

      Figure 28: Example resolution of an IPv6 address with redirect.

   1.   Lookup AAAA record for name: www.example.tld.gns.alt.

   2.   Determine start zone for www.example.tld.gns.alt.

   3.   Start zone: zk0 - Remainder: www.example.

   4.   Calculate q0=SHA512(ZKDF(zk0, "example")) and initiate GET(q0).

   5.   Retrieve and decrypt RRBLOCK consisting of a single PKEY record
        containing zk1.

   6.   Calculate q1=SHA512(ZKDF(zk1, "www")) and initiate GET(q1).

   7.   Retrieve and decrypt RRBLOCK consisting of a single REDIRECT
        record containing www2.+.

   8.   Calculate q2=SHA512(ZKDF(zk1, "www2")) and initiate GET(q2).





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   9.   Retrieve and decrypt RRBLOCK consisting of a single AAAA record
        containing the IPv6 address 2001:db8::1.

   10.  Return record set to application.

B.3.  GNS2DNS Example Resolution

                              Local Host                |   Remote
                                                        |   Storage
                                                        |
                                                        |    +---------+
                                                        |   /         /|
                                                        |  +---------+ |
   +-----------+ (1)      +----------+                  |  |         | |
   |           |          |          |      (4)         |  | Record  | |
   |Application|----------| Resolver |------------------|->| Storage | |
   |           |<---------|          |<-----------------|--|         |/
   +-----------+ (8)      +----------+      (5)         |  +---------+
                             A    A                     |
                             |    |    (6,7)            |
                       (2,3) |    +----------+          |
                             |               |          |
                             |               v          |
                          +---------+    +------------+ |
                         /   v     /|    | System DNS | |
                        +---------+ |    | resolver   | |
                        |         | |    +------------+ |
                        |  Start  | |                   |
                        |  Zones  | |                   |
                        |         |/                    |
                        +---------+                     |

    Figure 29: Example resolution of an IPv6 address with DNS handover.

   1.  Lookup AAAA record for name: www.example.gnu.gns.alt

   2.  Determine start zone for www.example.gnu.gns.alt.

   3.  Start zone: zk0 - Remainder: www.example.

   4.  Calculate q0=SHA512(ZKDF(zk0, "example")) and initiate GET(q0).

   5.  Retrieve and decrypt RRBLOCK consisting of a single GNS2DNS
       record containing the name example.com and the DNS server IPv4
       address 192.0.2.1.

   6.  Use system resolver to lookup an AAAA record for the DNS name
       www.example.com.



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   7.  Retrieve a DNS reply consisting of a single AAAA record
       containing the IPv6 address 2001:db8::1.

   8.  Return record set to application.

Appendix C.  Base32GNS

   Encoding converts a byte array into a string of symbols.  Decoding
   converts a string of symbols into a byte array.  Decoding fails if
   the input string has symbols outside the defined set.

   This table defines the encode and decode symbols for a given symbol
   value.  Each symbol value encodes 5 bits.  It can be used to
   implement the encoding by reading it as: A symbol "A" or "a" is
   decoded to a 5 bit value 10 when decoding.  A 5 bit block with a
   value of 18 is encoded to the character "J" when encoding.  If the
   bit length of the byte string to encode is not a multiple of 5 it is
   padded to the next multiple with zeroes.  In order to further
   increase tolerance for failures in character recognition, the letter
   "U" MUST be decoded to the same value as the letter "V" in Base32GNS.































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   Symbol      Decode            Encode
   Value       Symbol            Symbol
   0           0 O o             0
   1           1 I i L l         1
   2           2                 2
   3           3                 3
   4           4                 4
   5           5                 5
   6           6                 6
   7           7                 7
   8           8                 8
   9           9                 9
   10          A a               A
   11          B b               B
   12          C c               C
   13          D d               D
   14          E e               E
   15          F f               F
   16          G g               G
   17          H h               H
   18          J j               J
   19          K k               K
   20          M m               M
   21          N n               N
   22          P p               P
   23          Q q               Q
   24          R r               R
   25          S s               S
   26          T t               T
   27          V v U u           V
   28          W w               W
   29          X x               X
   30          Y y               Y
   31          Z z               Z

        Figure 30: The Base32GNS Alphabet Including the Additional U
                               Encode Symbol.

Appendix D.  Test Vectors

   The following test vectors can be used by implementations to test for
   conformance with this specification.  Unless indicated otherwise, the
   test vectors are provided as hexadecimal byte arrays.

D.1.  Base32GNS en-/decoding

   The following are test vectors for the Base32GNS encoding used for
   zTLDs.  The input strings are encoded without the zero terminator.



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   Base32GNS-Encode:
     Input string: "Hello World"
     Output string: "91JPRV3F41BPYWKCCG"

     Input bytes: 474e55204e616d652053797374656d
     Output string: "8X75A82EC5PPA82KF5SQ8SBD"

   Base32GNS-Decode:
     Input string: "91JPRV3F41BPYWKCCG"
     Output string: "Hello World"

     Input string: "91JPRU3F41BPYWKCCG"
     Output string: "Hello World"


D.2.  Record sets

   The test vectors include record sets with a variety of record types
   and flags for both PKEY and EDKEY zones.  This includes labels with
   UTF-8 characters to demonstrate internationalized labels.

   *(1) PKEY zone with ASCII label and one delegation record*


   Zone private key (d, big-endian):
     50 d7 b6 52 a4 ef ea df
     f3 73 96 90 97 85 e5 95
     21 71 a0 21 78 c8 e7 d4
     50 fa 90 79 25 fa fd 98

   Zone identifier (ztype|zkey):
     00 01 00 00 67 7c 47 7d
     2d 93 09 7c 85 b1 95 c6
     f9 6d 84 ff 61 f5 98 2c
     2c 4f e0 2d 5a 11 fe df
     b0 c2 90 1f

   zTLD:
   000G0037FH3QTBCK15Y8BCCNRVWPV17ZC7TSGB1C9ZG2TPGHZVFV1GMG3W

   Label:
     74 65 73 74 64 65 6c 65
     67 61 74 69 6f 6e

   Number of records (integer): 1

   Record #0 := (
     EXPIRATION: 8143584694000000 us



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     00 1c ee 8c 10 e2 59 80

     DATA_SIZE:
     00 20

     TYPE:
     00 01 00 00

     FLAGS:   00 01

     DATA:
     21 e3 b3 0f f9 3b c6 d3
     5a c8 c6 e0 e1 3a fd ff
     79 4c b7 b4 4b bb c7 48
     d2 59 d0 a0 28 4d be 84

   )

   RDATA:
     00 1c ee 8c 10 e2 59 80
     00 20 00 01 00 01 00 00
     21 e3 b3 0f f9 3b c6 d3
     5a c8 c6 e0 e1 3a fd ff
     79 4c b7 b4 4b bb c7 48
     d2 59 d0 a0 28 4d be 84

   Encryption NONCE|EXPIRATION|BLOCK COUNTER:
     e9 0a 00 61 00 1c ee 8c
     10 e2 59 80 00 00 00 01

   Encryption key (K):
     86 4e 71 38 ea e7 fd 91
     a3 01 36 89 9c 13 2b 23
     ac eb db 2c ef 43 cb 19
     f6 bf 55 b6 7d b9 b3 b3

   Storage key (q):
     4a dc 67 c5 ec ee 9f 76
     98 6a bd 71 c2 22 4a 3d
     ce 2e 91 70 26 c9 a0 9d
     fd 44 ce f3 d2 0f 55 a2
     73 32 72 5a 6c 8a fb bb
     b0 f7 ec 9a f1 cc 42 64
     12 99 40 6b 04 fd 9b 5b
     57 91 f8 6c 4b 08 d5 f4

   ZKDF(zkey):
     18 2b b6 36 ed a7 9f 79



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     57 11 bc 27 08 ad bb 24
     2a 60 44 6a d3 c3 08 03
     12 1d 03 d3 48 b7 ce b6

   Derived private key (d', big-endian):
     0a 4c 5e 0f 00 63 df ce
     db c8 c7 f2 b2 2c 03 0c
     86 28 b2 c2 cb ac 9f a7
     29 aa e6 1f 89 db 3e 9c

   BDATA:
     0c 1e da 5c c0 94 a1 c7
     a8 88 64 9d 25 fa ee bd
     60 da e6 07 3d 57 d8 ae
     8d 45 5f 4f 13 92 c0 74
     e2 6a c6 69 bd ee c2 34
     62 b9 62 95 2c c6 e9 eb

   RRBLOCK:
     00 00 00 a0 00 01 00 00
     18 2b b6 36 ed a7 9f 79
     57 11 bc 27 08 ad bb 24
     2a 60 44 6a d3 c3 08 03
     12 1d 03 d3 48 b7 ce b6
     0a d1 0b c1 3b 40 3b 5b
     25 61 26 b2 14 5a 6f 60
     c5 14 f9 51 ff a7 66 f7
     a3 fd 4b ac 4a 4e 19 90
     05 5c b8 7e 8d 1b fd 19
     aa 09 a4 29 f7 29 e9 f5
     c6 ee c2 47 0a ce e2 22
     07 59 e9 e3 6c 88 6f 35
     00 1c ee 8c 10 e2 59 80
     0c 1e da 5c c0 94 a1 c7
     a8 88 64 9d 25 fa ee bd
     60 da e6 07 3d 57 d8 ae
     8d 45 5f 4f 13 92 c0 74
     e2 6a c6 69 bd ee c2 34
     62 b9 62 95 2c c6 e9 eb


   *(2) PKEY zone with UTF-8 label and three records*









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   Zone private key (d, big-endian):
     50 d7 b6 52 a4 ef ea df
     f3 73 96 90 97 85 e5 95
     21 71 a0 21 78 c8 e7 d4
     50 fa 90 79 25 fa fd 98

   Zone identifier (ztype|zkey):
     00 01 00 00 67 7c 47 7d
     2d 93 09 7c 85 b1 95 c6
     f9 6d 84 ff 61 f5 98 2c
     2c 4f e0 2d 5a 11 fe df
     b0 c2 90 1f

   zTLD:
   000G0037FH3QTBCK15Y8BCCNRVWPV17ZC7TSGB1C9ZG2TPGHZVFV1GMG3W

   Label:
     e5 a4 a9 e4 b8 8b e7 84
     a1 e6 95 b5

   Number of records (integer): 3

   Record #0 := (
     EXPIRATION: 8143584694000000 us
     00 1c ee 8c 10 e2 59 80

     DATA_SIZE:
     00 10

     TYPE:
     00 00 00 1c

     FLAGS:   00 00

     DATA:
     00 00 00 00 00 00 00 00
     00 00 00 00 de ad be ef

   )

   Record #1 := (
     EXPIRATION: 17999736901000000 us
     00 3f f2 aa 54 08 db 40

     DATA_SIZE:
     00 06

     TYPE:



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     00 01 00 01

     FLAGS:   00 00

     DATA:
     e6 84 9b e7 a7 b0

   )

   Record #2 := (
     EXPIRATION: 11464693629000000 us
     00 28 bb 13 ff 37 19 40

     DATA_SIZE:
     00 0b

     TYPE:
     00 00 00 10

     FLAGS:   00 04

     DATA:
     48 65 6c 6c 6f 20 57 6f
     72 6c 64

   )

   RDATA:
     00 1c ee 8c 10 e2 59 80
     00 10 00 00 00 00 00 1c
     00 00 00 00 00 00 00 00
     00 00 00 00 de ad be ef
     00 3f f2 aa 54 08 db 40
     00 06 00 00 00 01 00 01
     e6 84 9b e7 a7 b0 00 28
     bb 13 ff 37 19 40 00 0b
     00 04 00 00 00 10 48 65
     6c 6c 6f 20 57 6f 72 6c
     64 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00

   Encryption NONCE|EXPIRATION|BLOCK COUNTER:
     ee 96 33 c1 00 1c ee 8c
     10 e2 59 80 00 00 00 01



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   Encryption key (K):
     fb 3a b5 de 23 bd da e1
     99 7a af 7b 92 c2 d2 71
     51 40 8b 77 af 7a 41 ac
     79 05 7c 4d f5 38 3d 01

   Storage key (q):
     af f0 ad 6a 44 09 73 68
     42 9a c4 76 df a1 f3 4b
     ee 4c 36 e7 47 6d 07 aa
     64 63 ff 20 91 5b 10 05
     c0 99 1d ef 91 fc 3e 10
     90 9f 87 02 c0 be 40 43
     67 78 c7 11 f2 ca 47 d5
     5c f0 b5 4d 23 5d a9 77

   ZKDF(zkey):
     a5 12 96 df 75 7e e2 75
     ca 11 8d 4f 07 fa 7a ae
     55 08 bc f5 12 aa 41 12
     14 29 d4 a0 de 9d 05 7e

   Derived private key (d', big-endian):
     0a be 56 d6 80 68 ab 40
     e1 44 79 0c de 9a cf 4d
     78 7f 2d 3c 63 b8 53 05
     74 6e 68 03 32 15 f2 ab

   BDATA:
     d8 c2 8d 2f d6 96 7d 1a
     b7 22 53 f2 10 98 b8 14
     a4 10 be 1f 59 98 de 03
     f5 8f 7e 7c db 7f 08 a6
     16 51 be 4d 0b 6f 8a 61
     df 15 30 44 0b d7 47 dc
     f0 d7 10 4f 6b 8d 24 c2
     ac 9b c1 3d 9c 6f e8 29
     05 25 d2 a6 d0 f8 84 42
     67 a1 57 0e 8e 29 4d c9
     3a 31 9f cf c0 3e a2 70
     17 d6 fd a3 47 b4 a7 94
     97 d7 f6 b1 42 2d 4e dd
     82 1c 19 93 4e 96 c1 aa
     87 76 57 25 d4 94 c7 64
     b1 55 dc 6d 13 26 91 74

   RRBLOCK:
     00 00 00 f0 00 01 00 00



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     a5 12 96 df 75 7e e2 75
     ca 11 8d 4f 07 fa 7a ae
     55 08 bc f5 12 aa 41 12
     14 29 d4 a0 de 9d 05 7e
     08 5b d6 5f d4 85 10 51
     ba ce 2a 45 2a fc 8a 7e
     4f 6b 2c 1f 74 f0 20 35
     d9 64 1a cd ba a4 66 e0
     00 ce d6 f2 d2 3b 63 1c
     8e 8a 0b 38 e2 ba e7 9a
     22 ca d8 1d 4c 50 d2 25
     35 8e bc 17 ac 0f 89 9e
     00 1c ee 8c 10 e2 59 80
     d8 c2 8d 2f d6 96 7d 1a
     b7 22 53 f2 10 98 b8 14
     a4 10 be 1f 59 98 de 03
     f5 8f 7e 7c db 7f 08 a6
     16 51 be 4d 0b 6f 8a 61
     df 15 30 44 0b d7 47 dc
     f0 d7 10 4f 6b 8d 24 c2
     ac 9b c1 3d 9c 6f e8 29
     05 25 d2 a6 d0 f8 84 42
     67 a1 57 0e 8e 29 4d c9
     3a 31 9f cf c0 3e a2 70
     17 d6 fd a3 47 b4 a7 94
     97 d7 f6 b1 42 2d 4e dd
     82 1c 19 93 4e 96 c1 aa
     87 76 57 25 d4 94 c7 64
     b1 55 dc 6d 13 26 91 74

   *(3) EDKEY zone with ASCII label and delegation record*


   Zone private key (d):
     5a f7 02 0e e1 91 60 32
     88 32 35 2b bc 6a 68 a8
     d7 1a 7c be 1b 92 99 69
     a7 c6 6d 41 5a 0d 8f 65

   Zone identifier (ztype|zkey):
     00 01 00 14 3c f4 b9 24
     03 20 22 f0 dc 50 58 14
     53 b8 5d 93 b0 47 b6 3d
     44 6c 58 45 cb 48 44 5d
     db 96 68 8f

   zTLD:
   000G051WYJWJ80S04BRDRM2R2H9VGQCKP13VCFA4DHC4BJT88HEXQ5K8HW



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   Label:
     74 65 73 74 64 65 6c 65
     67 61 74 69 6f 6e

   Number of records (integer): 1

   Record #0 := (
     EXPIRATION: 8143584694000000 us
     00 1c ee 8c 10 e2 59 80

     DATA_SIZE:
     00 20

     TYPE:
     00 01 00 00

     FLAGS:   00 01

     DATA:
     21 e3 b3 0f f9 3b c6 d3
     5a c8 c6 e0 e1 3a fd ff
     79 4c b7 b4 4b bb c7 48
     d2 59 d0 a0 28 4d be 84

   )

   RDATA:
     00 1c ee 8c 10 e2 59 80
     00 20 00 01 00 01 00 00
     21 e3 b3 0f f9 3b c6 d3
     5a c8 c6 e0 e1 3a fd ff
     79 4c b7 b4 4b bb c7 48
     d2 59 d0 a0 28 4d be 84

   Encryption NONCE|EXPIRATION:
     98 13 2e a8 68 59 d3 5c
     88 bf d3 17 fa 99 1b cb
     00 1c ee 8c 10 e2 59 80

   Encryption key (K):
     85 c4 29 a9 56 7a a6 33
     41 1a 96 91 e9 09 4c 45
     28 16 72 be 58 60 34 aa
     e4 a2 a2 cc 71 61 59 e2

   Storage key (q):
     ab aa ba c0 e1 24 94 59
     75 98 83 95 aa c0 24 1e



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     55 59 c4 1c 40 74 e2 55
     7b 9f e6 d1 54 b6 14 fb
     cd d4 7f c7 f5 1d 78 6d
     c2 e0 b1 ec e7 60 37 c0
     a1 57 8c 38 4e c6 1d 44
     56 36 a9 4e 88 03 29 e9

   ZKDF(zkey):
     9b f2 33 19 8c 6d 53 bb
     db ac 49 5c ab d9 10 49
     a6 84 af 3f 40 51 ba ca
     b0 dc f2 1c 8c f2 7a 1a

   nonce := SHA-256 (dh[32..63] || h):
     14 f2 c0 6b ed c3 aa 2d
     f0 71 13 9c 50 39 34 f3
     4b fa 63 11 a8 52 f2 11
     f7 3a df 2e 07 61 ec 35

   Derived private key (d', big-endian):
     3b 1b 29 d4 23 0b 10 a8
     ec 4d a3 c8 6e db 88 ea
     cd 54 08 5c 1d db 63 f7
     a9 d7 3f 7c cb 2f c3 98

   BDATA:
     57 7c c6 c9 5a 14 e7 04
     09 f2 0b 01 67 e6 36 d0
     10 80 7c 4f 00 37 2d 69
     8c 82 6b d9 2b c2 2b d6
     bb 45 e5 27 7c 01 88 1d
     6a 43 60 68 e4 dd f1 c6
     b7 d1 41 6f af a6 69 7c
     25 ed d9 ea e9 91 67 c3

   RRBLOCK:
     00 00 00 b0 00 01 00 14
     9b f2 33 19 8c 6d 53 bb
     db ac 49 5c ab d9 10 49
     a6 84 af 3f 40 51 ba ca
     b0 dc f2 1c 8c f2 7a 1a
     9f 56 a8 86 ea 73 9d 59
     17 50 8f 9b 75 56 39 f3
     a9 ac fa ed ed ca 7f bf
     a7 94 b1 92 e0 8b f9 ed
     4c 7e c8 59 4c 9f 7b 4e
     19 77 4f f8 38 ec 38 7a
     8f 34 23 da ac 44 9f 59



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     db 4e 83 94 3f 90 72 00
     00 1c ee 8c 10 e2 59 80
     57 7c c6 c9 5a 14 e7 04
     09 f2 0b 01 67 e6 36 d0
     10 80 7c 4f 00 37 2d 69
     8c 82 6b d9 2b c2 2b d6
     bb 45 e5 27 7c 01 88 1d
     6a 43 60 68 e4 dd f1 c6
     b7 d1 41 6f af a6 69 7c
     25 ed d9 ea e9 91 67 c3

   *(4) EDKEY zone with UTF-8 label and three records*


   Zone private key (d):
     5a f7 02 0e e1 91 60 32
     88 32 35 2b bc 6a 68 a8
     d7 1a 7c be 1b 92 99 69
     a7 c6 6d 41 5a 0d 8f 65

   Zone identifier (ztype|zkey):
     00 01 00 14 3c f4 b9 24
     03 20 22 f0 dc 50 58 14
     53 b8 5d 93 b0 47 b6 3d
     44 6c 58 45 cb 48 44 5d
     db 96 68 8f

   zTLD:
   000G051WYJWJ80S04BRDRM2R2H9VGQCKP13VCFA4DHC4BJT88HEXQ5K8HW

   Label:
     e5 a4 a9 e4 b8 8b e7 84
     a1 e6 95 b5

   Number of records (integer): 3

   Record #0 := (
     EXPIRATION: 8143584694000000 us
     00 1c ee 8c 10 e2 59 80

     DATA_SIZE:
     00 10

     TYPE:
     00 00 00 1c

     FLAGS:   00 00




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     DATA:
     00 00 00 00 00 00 00 00
     00 00 00 00 de ad be ef

   )

   Record #1 := (
     EXPIRATION: 17999736901000000 us
     00 3f f2 aa 54 08 db 40

     DATA_SIZE:
     00 06

     TYPE:
     00 01 00 01

     FLAGS:   00 00

     DATA:
     e6 84 9b e7 a7 b0

   )

   Record #2 := (
     EXPIRATION: 11464693629000000 us
     00 28 bb 13 ff 37 19 40

     DATA_SIZE:
     00 0b

     TYPE:
     00 00 00 10

     FLAGS:   00 04

     DATA:
     48 65 6c 6c 6f 20 57 6f
     72 6c 64

   )

   RDATA:
     00 1c ee 8c 10 e2 59 80
     00 10 00 00 00 00 00 1c
     00 00 00 00 00 00 00 00
     00 00 00 00 de ad be ef
     00 3f f2 aa 54 08 db 40
     00 06 00 00 00 01 00 01



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     e6 84 9b e7 a7 b0 00 28
     bb 13 ff 37 19 40 00 0b
     00 04 00 00 00 10 48 65
     6c 6c 6f 20 57 6f 72 6c
     64 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00
     00 00 00 00 00 00 00 00

   Encryption NONCE|EXPIRATION:
     bb 0d 3f 0f bd 22 42 77
     50 da 5d 69 12 16 e6 c9
     00 1c ee 8c 10 e2 59 80

   Encryption key (K):
     3d f8 05 bd 66 87 aa 14
     20 96 28 c2 44 b1 11 91
     88 c3 92 56 37 a4 1e 5d
     76 49 6c 29 45 dc 37 7b

   Storage key (q):
     ba f8 21 77 ee c0 81 e0
     74 a7 da 47 ff c6 48 77
     58 fb 0d f0 1a 6c 7f bb
     52 fc 8a 31 be f0 29 af
     74 aa 0d c1 5a b8 e2 fa
     7a 54 b4 f5 f6 37 f6 15
     8f a7 f0 3c 3f ce be 78
     d3 f9 d6 40 aa c0 d1 ed

   ZKDF(zkey):
     74 f9 00 68 f1 67 69 53
     52 a8 a6 c2 eb 98 48 98
     c5 3a cc a0 98 04 70 c6
     c8 12 64 cb dd 78 ad 11

   nonce := SHA-256 (dh[32..63] || h):
     f8 6a b5 33 8a 74 d7 a1
     d2 77 ea 11 ff 95 cb e8
     3a cf d3 97 3b b4 ab ca
     0a 1b 60 62 c3 7a b3 9c

   Derived private key (d', big-endian):
     17 c0 68 a6 c3 f7 20 de
     0e 1b 69 ff 3f 53 e0 5d
     3f e5 c5 b0 51 25 7a 89



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     a6 3c 1a d3 5a c4 35 58

   BDATA:
     4e b3 5a 50 d4 0f e1 a4
     29 c7 f4 b2 67 a0 59 de
     4e 2c 8a 89 a5 ed 53 d3
     d4 92 58 59 d2 94 9f 7f
     30 d8 a2 0c aa 96 f8 81
     45 05 2d 1c da 04 12 49
     8f f2 5f f2 81 6e f0 ce
     61 fe 69 9b fa c7 2c 15
     dc 83 0e a9 b0 36 17 1c
     cf ca bb dd a8 de 3c 86
     ed e2 95 70 d0 17 4b 82
     82 09 48 a9 28 b7 f0 0e
     fb 40 1c 10 fe 80 bb bb
     02 76 33 1b f7 f5 1b 8d
     74 57 9c 14 14 f2 2d 50
     1a d2 5a e2 49 f5 bb f2
     a6 c3 72 59 d1 75 e4 40
     b2 94 39 c6 05 19 cb b1

   RRBLOCK:
     00 00 01 00 00 01 00 14
     74 f9 00 68 f1 67 69 53
     52 a8 a6 c2 eb 98 48 98
     c5 3a cc a0 98 04 70 c6
     c8 12 64 cb dd 78 ad 11
     75 6d 2c 15 7a d2 ea 4f
     c0 b1 b9 1c 08 03 79 44
     61 d3 de f2 0d d1 63 6c
     fe dc 03 89 c5 49 d1 43
     6c c3 5b 4e 1b f8 89 5a
     64 6b d9 a6 f4 6b 83 48
     1d 9c 0e 91 d4 e1 be bb
     6a 83 52 6f b7 25 2a 06
     00 1c ee 8c 10 e2 59 80
     4e b3 5a 50 d4 0f e1 a4
     29 c7 f4 b2 67 a0 59 de
     4e 2c 8a 89 a5 ed 53 d3
     d4 92 58 59 d2 94 9f 7f
     30 d8 a2 0c aa 96 f8 81
     45 05 2d 1c da 04 12 49
     8f f2 5f f2 81 6e f0 ce
     61 fe 69 9b fa c7 2c 15
     dc 83 0e a9 b0 36 17 1c
     cf ca bb dd a8 de 3c 86
     ed e2 95 70 d0 17 4b 82



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     82 09 48 a9 28 b7 f0 0e
     fb 40 1c 10 fe 80 bb bb
     02 76 33 1b f7 f5 1b 8d
     74 57 9c 14 14 f2 2d 50
     1a d2 5a e2 49 f5 bb f2
     a6 c3 72 59 d1 75 e4 40
     b2 94 39 c6 05 19 cb b1

D.3.  Zone revocation

   The following is an example revocation for a PKEY zone:


   Zone private key (d, big-endian):
     6f ea 32 c0 5a f5 8b fa
     97 95 53 d1 88 60 5f d5
     7d 8b f9 cc 26 3b 78 d5
     f7 47 8c 07 b9 98 ed 70

   Zone identifier (ztype|zkey):
     00 01 00 00 2c a2 23 e8
     79 ec c4 bb de b5 da 17
     31 92 81 d6 3b 2e 3b 69
     55 f1 c3 77 5c 80 4a 98
     d5 f8 dd aa

   Encoded zone identifier (zkl = zTLD):
   000G001CM8HYGYFCRJXXXDET2WRS50EP7CQ3PTANY71QEQ409ACDBY6XN8

   Difficulty (5 base difficulty + 2 epochs): 7

   Signed message:
     00 00 00 34 00 00 00 03
     00 05 ff 1c 56 e4 b2 68
     00 01 00 00 2c a2 23 e8
     79 ec c4 bb de b5 da 17
     31 92 81 d6 3b 2e 3b 69
     55 f1 c3 77 5c 80 4a 98
     d5 f8 dd aa

   Proof:
     00 05 ff 1c 56 e4 b2 68
     00 00 39 5d 18 27 c0 00
     38 0b 54 aa 70 16 ac a2
     38 0b 54 aa 70 16 ad 62
     38 0b 54 aa 70 16 af 3e
     38 0b 54 aa 70 16 af 93
     38 0b 54 aa 70 16 b0 bf



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     38 0b 54 aa 70 16 b0 ee
     38 0b 54 aa 70 16 b1 c9
     38 0b 54 aa 70 16 b1 e5
     38 0b 54 aa 70 16 b2 78
     38 0b 54 aa 70 16 b2 b2
     38 0b 54 aa 70 16 b2 d6
     38 0b 54 aa 70 16 b2 e4
     38 0b 54 aa 70 16 b3 2c
     38 0b 54 aa 70 16 b3 5a
     38 0b 54 aa 70 16 b3 9d
     38 0b 54 aa 70 16 b3 c0
     38 0b 54 aa 70 16 b3 dd
     38 0b 54 aa 70 16 b3 f4
     38 0b 54 aa 70 16 b4 42
     38 0b 54 aa 70 16 b4 76
     38 0b 54 aa 70 16 b4 8c
     38 0b 54 aa 70 16 b4 a4
     38 0b 54 aa 70 16 b4 c9
     38 0b 54 aa 70 16 b4 f0
     38 0b 54 aa 70 16 b4 f7
     38 0b 54 aa 70 16 b5 79
     38 0b 54 aa 70 16 b6 34
     38 0b 54 aa 70 16 b6 8e
     38 0b 54 aa 70 16 b7 b4
     38 0b 54 aa 70 16 b8 7e
     38 0b 54 aa 70 16 b8 f8
     38 0b 54 aa 70 16 b9 2a
     00 01 00 00 2c a2 23 e8
     79 ec c4 bb de b5 da 17
     31 92 81 d6 3b 2e 3b 69
     55 f1 c3 77 5c 80 4a 98
     d5 f8 dd aa 08 ca ff de
     3c 6d f1 45 f7 e0 79 81
     15 37 b2 b0 42 2d 5e 1f
     b2 01 97 81 ec a2 61 d1
     f9 d8 ea 81 0a bc 2f 33
     47 7f 04 e3 64 81 11 be
     71 c2 48 82 1a d6 04 f4
     94 e7 4d 0b f5 11 d2 c1
     62 77 2e 81


   The following is an example revocation for an EDKEY zone:








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   Zone private key (d):
     5a f7 02 0e e1 91 60 32
     88 32 35 2b bc 6a 68 a8
     d7 1a 7c be 1b 92 99 69
     a7 c6 6d 41 5a 0d 8f 65

   Zone identifier (ztype|zkey):
     00 01 00 14 3c f4 b9 24
     03 20 22 f0 dc 50 58 14
     53 b8 5d 93 b0 47 b6 3d
     44 6c 58 45 cb 48 44 5d
     db 96 68 8f

   Encoded zone identifier (zkl = zTLD):
   000G051WYJWJ80S04BRDRM2R2H9VGQCKP13VCFA4DHC4BJT88HEXQ5K8HW

   Difficulty (5 base difficulty + 2 epochs): 7

   Signed message:
     00 00 00 34 00 00 00 03
     00 05 ff 1c 57 35 42 bd
     00 01 00 14 3c f4 b9 24
     03 20 22 f0 dc 50 58 14
     53 b8 5d 93 b0 47 b6 3d
     44 6c 58 45 cb 48 44 5d
     db 96 68 8f

   Proof:
     00 05 ff 1c 57 35 42 bd
     00 00 39 5d 18 27 c0 00
     58 4c 93 3c b0 99 2a 08
     58 4c 93 3c b0 99 2d f7
     58 4c 93 3c b0 99 2e 21
     58 4c 93 3c b0 99 2e 2a
     58 4c 93 3c b0 99 2e 53
     58 4c 93 3c b0 99 2e 8e
     58 4c 93 3c b0 99 2f 13
     58 4c 93 3c b0 99 2f 2d
     58 4c 93 3c b0 99 2f 3c
     58 4c 93 3c b0 99 2f 41
     58 4c 93 3c b0 99 2f fd
     58 4c 93 3c b0 99 30 33
     58 4c 93 3c b0 99 30 82
     58 4c 93 3c b0 99 30 a2
     58 4c 93 3c b0 99 30 e1
     58 4c 93 3c b0 99 31 ce
     58 4c 93 3c b0 99 31 de
     58 4c 93 3c b0 99 32 12



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     58 4c 93 3c b0 99 32 4e
     58 4c 93 3c b0 99 32 9f
     58 4c 93 3c b0 99 33 31
     58 4c 93 3c b0 99 33 87
     58 4c 93 3c b0 99 33 8c
     58 4c 93 3c b0 99 33 e5
     58 4c 93 3c b0 99 33 f3
     58 4c 93 3c b0 99 34 26
     58 4c 93 3c b0 99 34 30
     58 4c 93 3c b0 99 34 68
     58 4c 93 3c b0 99 34 88
     58 4c 93 3c b0 99 34 8a
     58 4c 93 3c b0 99 35 4c
     58 4c 93 3c b0 99 35 bd
     00 01 00 14 3c f4 b9 24
     03 20 22 f0 dc 50 58 14
     53 b8 5d 93 b0 47 b6 3d
     44 6c 58 45 cb 48 44 5d
     db 96 68 8f 04 ae 26 f7
     63 56 5a b7 aa ab 01 71
     72 4f 3c a8 bc c5 1a 98
     b7 d4 c9 2e a3 3c d9 34
     4c a8 b6 3e 04 53 3a bf
     1a 3c 05 49 16 b3 68 2c
     5c a8 cb 4d d0 f8 4c 3b
     77 48 7a ac 6e ce 38 48
     0b a9 d5 00


Authors' Addresses

   Martin Schanzenbach
   Fraunhofer AISEC
   Lichtenbergstrasse 11
   85748 Garching
   Germany
   Email: martin.schanzenbach@aisec.fraunhofer.de


   Christian Grothoff
   Berner Fachhochschule
   Hoeheweg 80
   CH-2501 Biel/Bienne
   Switzerland
   Email: christian.grothoff@bfh.ch






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   Bernd Fix
   GNUnet e.V.
   Boltzmannstrasse 3
   85748 Garching
   Germany
   Email: fix@gnunet.org













































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