Internet DRAFT - draft-grothoff-iesg-special-use-p2p-bit
draft-grothoff-iesg-special-use-p2p-bit
Internet Engineering Task Force C. Grothoff
Internet-Draft INRIA
Intended status: Informational M. Wachs
Expires: December 24, 2015 Technische Universitaet Muenchen
H. Wolf, Ed.
GNU consensus
J. Appelbaum
L. Ryge
Tor Project Inc.
June 30, 2015
Special-Use Domain Name for Namecoin
draft-grothoff-iesg-special-use-p2p-bit-00
Abstract
This document registers a Special-Use Domain Name for use with the
Namecoin system, as per RFC6761.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 24, 2015.
Copyright Notice
Copyright (c) 2015 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
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include Simplified BSD License text as described in Section 4.e of
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Terminology and Conventions Used in This Document . . . . . . 3
4. The "BIT" Timeline System pTLD . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The Domain Name System (DNS) is primarily used to map human-memorable
names to IP addresses, which are used for routing but generally not
meaningful for humans.
Namecoin offers a specific timeline-based mechanism to allocate,
register, manage, and resolve names, independently from the DNS root
and delegation tree.
As compatibility with applications using domain names is desired,
Namecoin uses an exclusive alternative Top-Level Domain to avoid
conflicts between the Namecoin namespace and the DNS hierarchy.
In order to avoid interoperability issues with DNS as well as to
address security and privacy concerns, this document registers the
Special-Use Domain Names "BIT" for use with Namecoin, as per
[RFC6761].
Namecoin (also known as the Dot-Bit Project) uses this pTLD to
realize censorship-resistant naming.
2. Applicability
[RFC6761] Section 3 states:
"[I]f a domain name has special properties that affect the way
hardware and software implementations handle the name, that apply
universally regardless of what network the implementation may be
connected to, then that domain name may be a candidate for having
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the IETF declare it to be a Special-Use Domain Name and specify
what special treatment implementations should give to that name.
On the other hand, if declaring a given name to be special would
result in no change to any implementations, then that suggests
that the name may not be special in any material way, and it may
be more appropriate to use the existing DNS mechanisms [RFC1034]
to provide the desired delegation, data, or lack-of-data, for the
name in question. Where the desired behaviour can be achieved via
the existing domain name registration processes, that process
should be used. Reservation of a Special-Use Domain Name is not a
mechanism for circumventing normal domain name registration
processes."
The Special-Use Domain Name for Namecoin reserved by this document
meets this requirement, as it has the following specificities:
o The "BIT" pTLD is not manageable by some designated
administration. Instead, it is managed by a P2P protocol using a
global public ledger.
o Namecoin does not depend on the DNS context for their resolution:
Namecoin domains MAY use the DNS servers infrastructure, as they
return DNS-compatible results; but it uses specific P2P protocols
for regular name resolution, covered by the respective protocol
specifications.
o When Namecoin is properly implemented, the implementation MUST
intercept queries for the pTLD to ensure Namecoin names cannot
leak into the DNS.
o The appropriate pTLD protocols can be implemented in existing
software libraries and APIs to extend regular DNS operation and
enable Namecoin name resolution. However, the default
hierarchical DNS response to any request to any pTLD MUST be
NXDOMAIN.
o Finally, in order for Namecoin to realize a censorship-resistant
name system, this document specifies changes required in existing
DNS software and DNS operations.
3. Terminology and Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The word "peer" is used in the meaning of a individual system on the
network.
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The abbreviation "pTLD" is used in this document to mean a pseudo
Top-Level Domain, i.e., a Special-Use Domain Name per [RFC6761]
reserved to P2P Systems in this document. A pTLD is mentioned in
capitals, and within double quotes to mark the difference with a
regular DNS gTLD.
In this document, ".tld" (lowercase, with quotes) means: any domain
or hostname within the scope of a given pTLD, while .tld (lowercase,
without quotes) refers to an adjective form. For example, a
collection of ".bit" peers in "BIT", but an .bit URL. [TO REMOVE: in
the IANA Considerations section, we use the simple .tld format to
request TLD reservation for consistency with previous RFCs].
The word "NXDOMAIN" refers to an alternate expression for the "Name
Error" RCODE as described in section 4.1.1 of [RFC1035]. When
referring to "NXDOMAIN" and negative caching [RFC2308] response, this
document means an authoritative (AA=1) name error (RCODE=3) response
exclusively.
4. The "BIT" Timeline System pTLD
Namecoin is a timeline-based system in the style of Bitcoin to create
a global, secure, and memorable name system. It creates a single,
globally accessible, append-only timeline of name registrations.
Timeline-based systems rely on a peer-to-peer network to manage
updates and store the timeline. In the Namecoin system,
modifications to key-value mapping are attached to transactions which
are committed to the timeline by "mining". Mining is a proof-of-work
calculation that uses brute-force methods to find (partial) hash
collisions with a state summary (fingerprint) representing the
complete global state -- including the full history -- of the
timeline .
"BIT" provides a name space where names are registered via
transactions in the Namecoin currency [Namecoin]. Like Bitcoins,
Namecoins are used to establish a decentralized, multi-party
consensus on the valid transaction history, and thus the set of
registered names and their values [SquareZooko].
The Namecoin used in a transaction to register a name in "BIT" is
lost. This is not a fundamental problem as more coins can be
generated via mining (proof-of-work calculations). The registration
cost is set to decrease over time, to prevent early adopters from
registering too many names.
The owner of a name can update the associated value by issuing an
update, which is a transaction that uses a special coin. This coin
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is generated as change during the registration operation. If a name
is not updated for a long time, the registration expires.
Performing a lookup for a name with Namecoin consists in checking the
timeline for correctness to ensure the validity of the blockchain,
and traversing it to see if it contains an entry for the desired
name. Namecoin supports resolution for other peer-to-peer systems
such as ".onion" and ".i2p" via specific resource records.
Like DNS registry, the Dot-Bit registry is public. But unlike DNS,
the public registry is maintained by network consensus on the
blockchain. It departs from DNS in three ways:
first, domain names are not delegated to an authority that can
assign them, but acquired by the operating party (the "domain
owner"), in the form of a historical claim made directly by
appending to the Namecoin blockchain. The domain is thus bound
not to a legal contract with an administrative authority, but to a
cryptographic coin, and the network consensus on the timeline.
second, the timeline contains the entire registry for all .bit
domains: the Namecoin blockchain itself is the complete domain
database. As participant peers maintain the consensus on the
timeline, they store a local copy of the Namecoin blockchain.
Therefore, to those peers, name resolution and registry traversal
are both local and private. Each participant theoretically has
the whole domain's database. In practice, some users can trust a
name server to access the Namecoin blockchain on their behalf.
third, the Namecoin system is not limited to domain names and can
store arbitrary data types. Each record must follow the same
rules (expiry time, data size limits, etc.). The Namecoin's
Domain Name Specification [Namecoin-DNS] defines the "d namespace"
for use with "BIT" and other unrelated namespaces co-exist on the
Namecoin blockchain.
The "BIT" domain is special in the following ways:
1. Users can use these names as they would other domain names,
entering them anywhere that they would otherwise enter a
conventional DNS domain name.
From the user's perspective, the resolution of .bit names is
similar to the normal DNS resolution, and thus should not affect
normal usage of most Internet applications.
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2. Application software SHOULD NOT recognize .bit domains as special
and SHOULD treat them as they would other domains.
Applications MAY pass requests to the "BIT" pTLD to DNS resolvers
and libraries if A/AAAA records are desired. If available, the
local resolver can intercept such requests within the respective
operating system hooks and return DNS-compatible results.
Namecoin-aware applications MAY choose to talk directly to the
respective P2P resolver, and use this to access additional record
types that are not defined in DNS.
3. Name resolution APIs and libraries SHOULD either respond to
requests for .bit names by resolving them via the Namecoin
protocol, or respond with NXDOMAIN.
4. Caching DNS servers SHOULD recognize .bit names as special and
SHOULD NOT attempt to resolve them. Instead, caching DNS servers
SHOULD generate immediate negative responses for all such
queries.
Given that .bit users typically have no special privacy
expectations, and those names are globally unique, local caching
DNS servers MAY choose to treat them as regular domain names, and
cache the responses obtained from the Namecoin blockchain. In
that case however, NXDOMAIN results SHOULD NOT be cached, as new
.bit domains may become active at any time.
5. Authoritative DNS servers are not expected to treat .bit domain
requests specially. In practice, they MUST answer with NXDOMAIN,
as "BIT" is not available via global DNS resolution.
6. DNS server operators SHOULD be aware that .bit names are reserved
for use with Namecoin, and MUST NOT override their resolution
(e.g., to redirect users to another service or error
information).
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7. DNS registries/registrars MUST NOT grant any request to register
.bit names. This helps avoid conflicts [SAC45]. These names are
defined by the Namecoin protocol specification, and they fall
outside the set of names available for allocation by registries/
registrars.
5. Security Considerations
Specific software performs the resolution of Namecoin Special-Use
Domain Names presented in this document; this resolution process
happens outside of the scope of DNS. Leakage of requests to such
domains to the global operational DNS can cause interception of
traffic that might be misused to monitor, censor, or abuse the user's
trust, and lead to privacy issues with potentially tragic
consequences for the user.
This document reserves these Top-Level Domain names to minimize the
possibility of confusion, conflict, and especially privacy risks for
users.
In the introduction of this document, there's a requirement that DNS
operators do not override resolution of the Namecoin names. This is
a regulatory measure and cannot prevent such malicious abuse in
practice. Its purpose is to limit any information leak that would
result from incorrectly configured systems, and to avoid that
resolvers make unnecessary contact to the DNS Root Zone for such
domains. Verisign, Inc., as well as several Internet service
providers (ISPs) have notoriously abused their position to override
NXDOMAIN responses to their customers in the past
[SSAC-NXDOMAIN-Abuse]. For example, if a DNS operator would decide
to override NXDOMAIN and send advertising to leaked .onion sites, the
information leak to the DNS would extend to the advertising server,
with unpredictable consequences. Thus, implementors should be aware
that any positive response coming from DNS must be considered with
extra care, as it suggests a leak to DNS has been made, contrary to
user's privacy expectations.
The reality of X.509 Certificate Authorities (CAs) creating
misleading certificates for these pTLDs due to ignorance stresses the
need to document their special use. X.509 Certificate Authorities
MAY create certificates for "BIT", given CSRs signed with the
respective private keys corresponding to the respective names. For
"BIT", the Certificate Authority SHOULD limit the expiration time of
the certificate to match the registration.
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Because the Namecoin system uses a timeline-based blockchain for name
assignment and resolution, it grants query privacy to the users who
maintain their own copy of the blockchain (Section 4.4), but the
entire zone of a .bit domains is publicly available in the Namecoin
blockchain, making enumeration of names within a .bit zone ("zone
walking") a trivial attack to conduct. This might be a concern to
some domain operators as it exposes their infrastructure to potential
adversaries. That concern may be addressed in future versions of
Namecoin, but the records already in the blockchain will remain there
unprotected.
Finally, legacy applications that do not explicitly support the
Namecoin pTLD significantly increase the risk of ".bit" queries
escaping to DNS, as they are entirely dependent on the correct
configuration on the operating system.
6. IANA Considerations
The Internet Assigned Numbers Authority (IANA) reserved the following
entries in the Special-Use Domain Names registry [RFC6761]:
.bit
[TO REMOVE: the assignement URL is https://www.iana.org/assignments/
special-use-domain-names/ ]
7. Acknowledgements
The authors thank the I2P and Namecoin developers for their
constructive feedback, as well as Mark Nottingham for his proof-
reading and valuable feedback. The authors also thank the members of
DNSOP WG for their critiques and suggestions.
8. References
8.1. Normative References
[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, November 1987.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS
NCACHE)", RFC 2308, March 1998.
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[RFC6761] Cheshire, S. and M. Krochmal, "Special-Use Domain Names",
RFC 6761, February 2013.
8.2. Informative References
[Namecoin]
The .bit Project, "Namecoin", 2013,
<https://namecoin.org/>.
[Namecoin-DNS]
The .bit Project, "Namecoin Domain Name Specification",
2015, <https://bit.namecoin.org/spec>.
[SAC45] ICANN Security and Stability Advisory Committee, "Invalid
Top Level Domain Queries at the Root Level of the Domain
Name System", November 2010,
<http://www.icann.org/en/groups/ssac/documents/
sac-045-en.pdf>.
[SquareZooko]
Swartz, A., "Squaring the Triangle: Secure, Decentralized,
Human-Readable Names", 2011,
<http://www.aaronsw.com/weblog/squarezooko>.
[SSAC-NXDOMAIN-Abuse]
ICANN Security and Stability Advisory Committee,
"Redirection in the COM and NET Domains", July 2004,
<http://www.icann.org/committees/security/
ssac-report-09jul04.pdf>.
Authors' Addresses
Christian Grothoff
INRIA
Equipe Decentralisee
INRIA Rennes Bretagne Atlantique
263 avenue du General Leclerc
Campus Universitaire de Beaulieu
Rennes, Bretagne F-35042
FR
Email: christian@grothoff.org
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Matthias Wachs
Technische Universitaet Muenchen
Free Secure Network Systems Group
Lehrstuhl fuer Netzarchitekturen und Netzdienste
Boltzmannstrasse 3
Technische Universitaet Muenchen
Garching bei Muenchen, Bayern D-85748
DE
Email: wachs@net.in.tum.de
Hellekin O. Wolf (editor)
GNU consensus
Email: hellekin@gnu.org
Jacob Appelbaum
Tor Project Inc.
Email: jacob@appelbaum.net
Leif Ryge
Tor Project Inc.
Email: leif@synthesize.us
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