Internet DRAFT - draft-vandijk-dnsop-ds-digest-verbatim
draft-vandijk-dnsop-ds-digest-verbatim
dnsop P. van Dijk
Internet-Draft PowerDNS
Intended status: Standards Track 10 August 2021
Expires: 11 February 2022
The VERBATIM Digest Algorithm for DS records
draft-vandijk-dnsop-ds-digest-verbatim-01
Abstract
The VERBATIM DS Digest is defined as a direct copy of the input data
without any hashing.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 11 February 2022.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Document work . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Conventions and Definitions . . . . . . . . . . . . . . . . . 3
4. Implementation . . . . . . . . . . . . . . . . . . . . . . . 3
4.1. Authoritative server changes . . . . . . . . . . . . . . 3
4.2. Validating resolver changes . . . . . . . . . . . . . . . 3
4.3. Stub resolver changes . . . . . . . . . . . . . . . . . . 3
4.4. Zone validator changes . . . . . . . . . . . . . . . . . 3
4.5. Domain registry changes . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. Implementation Status . . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
9. Normative References . . . . . . . . . . . . . . . . . . . . 4
10. Informative References . . . . . . . . . . . . . . . . . . . 5
Appendix A. Document history . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
The currently defined DS Digest Algorithms take the input data and
hash it into a fixed-length form using well defined hashing
algorithms (several SHA variants, and one mostly unused GOST
algorithm). That hashing operation makes any data inside the
(C)DNSKEY record unreachable until that data is retrieved from the
child zone. Thus, DS records do not actually convey information;
they merely verify information that can be retrieved elsewhere.
A DS record set can only answer the question 'this data that I have
here, do you recognise it?'. In that sense, DS records are not
information sources - they are boolean oracles. For several imagined
use cases for signed data at the parent, this might not be
sufficient. One such use case is https://datatracker.ietf.org/doc/
draft-schwartz-ds-glue/ (https://datatracker.ietf.org/doc/draft-
schwartz-ds-glue/) [FIXME: make this a proper ref].
This document introduces a new Digest Algorithm, proposed name
VERBATIM (alternative suggestion: NULL). The VERBATIM Digest
Algorithm takes the input data (DNSKEY owner name | DNSKEY RDATA per
section 5.1.4 of [RFC4034]) and copies it unmodified into the DS
Digest field.
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2. Document work
This document lives on GitHub (https://github.com/PowerDNS/draft-
dnsop-ds-digest-verbatim); proposed text and editorial changes are
very much welcomed there, but any functional changes should always
first be discussed on the IETF DNSOP WG mailing list.
3. Conventions and Definitions
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.
4. Implementation
The subsection titles in this section attempt to follow the
terminology from [RFC8499] in as far as it has suitable terms.
'Implementation' is understood to mean both 'code changes' and
'operational changes' here.
4.1. Authoritative server changes
None, except where related tooling emits DS records to the
administrator.
4.2. Validating resolver changes
Validating resolvers are encouraged to implement the VERBATIM Digest
Algorithm.
4.3. Stub resolver changes
This specification defines no changes to query processing in stub
resolvers.
4.4. Zone validator changes
Zone validators are encouraged to recognise the VERBATIM Digest
Algorithm and, where possible, verify it against the child zone's
DNSKEY, if it has any for the given algorithm.
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4.5. Domain registry changes
Domain registries are encouraged to allow VERBATIM digests at their
user's request. However, a likely outcome is that domain registries
will only allow the VERBATIM digest for DNSSEC algorithms whose
specifications call for use of the VERBATIM digest.
5. Security Considerations
Previously existing DS Digest Algorithms have a fixed size output.
The VERBATIM digest has a variable size output, that may be under the
control of a third party, like the owner of a delegated domain. Such
a third party might cause zone files to grow very big with just a few
data submissions to a registrar/registry. DNS query responses
containing VERBATIM digests might also be bigger than is desired.
Implementors, specifically domain registries, may want to limit use
of VERBATIM to specified use cases, and with limits appropriate to
those use cases.
6. Implementation Status
[RFC Editor: please remove this section before publication]
7. IANA Considerations
This document updates the IANA registry "Delegation Signer (DS)
Resource Record (RR) Type Digest Algorithms" at
https://www.iana.org/assignments/ds-rr-types/ds-rr-types.xhtml
(https://www.iana.org/assignments/ds-rr-types/ds-rr-types.xhtml)
The following entry is added to the registry:
+--------------+----------------+
| Value | TBD |
| Description | VERBATIM |
| Status | OPTIONAL |
| Reference | RFC TBD2 |
+--------------+----------------+
8. Acknowledgements
9. Normative References
[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>.
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[RFC4034] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "Resource Records for the DNS Security Extensions",
RFC 4034, DOI 10.17487/RFC4034, March 2005,
<https://www.rfc-editor.org/info/rfc4034>.
10. Informative References
[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>.
Appendix A. Document history
Author's Address
Peter van Dijk
PowerDNS
Den Haag
Netherlands
Email: peter.van.dijk@powerdns.com
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