Network Working Group M. Andrews
Internet-Draft ISC
Intended status: Standards Track 31 May 2025
Expires: 2 December 2025
DS support for private DNSSEC algorithms
draft-andrews-ds-support-for-private-algorithms-01
Abstract
Extend the DS digest field of the DS record to identify the private
DNSSEC algorithm of the DNSKEY matching the DS record.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Reserved Words . . . . . . . . . . . . . . . . . . . . . 2
2. Updated DS digest field structure . . . . . . . . . . . . . . 3
3. New DS Types . . . . . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. Normative References . . . . . . . . . . . . . . . . . . . . 3
Appendix A. Example . . . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
When the DNSSEC algorithm is PRIVATEDNS (233) or PRIVATEOID (254) the
private algorithm identifier is embedded at the start of the key data
in KEY, CDNSKEY, and DNSKEY records and at the start of the signature
data in the RRSIG and SIG records [RFC4034]. This allows the private
algorithm to be fully identified.
DS records, however, do not embed this identifier at the start of the
digest field. This results in PRIVATEDNS and PRIVATEOID keys not
being able to be used in all the scenarios where non private key
algorithms can be. i.e. publishing of DS records for yet to be
published DNSKEYs, determining if a DS based trust anchor represents
a supported algorithm.
This document adds DS digest types which embed the private algorithm
identifiers to the start of the digest field to provide equivalent
functionality to PRIVATE key types as described in [RFC4034],
Appendix A.1.1.
This document was inspired by the work done to add private DNSSEC
algorithm support to BIND 9.
1.1. Reserved Words
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].
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2. Updated DS digest field structure
The digest field of CDS and DS records with digest types other than
SHA-1 (1), SHA-256 (2), GOST R 34.11-94 (3), SHA-384 (4), GOST R
34.11-2012 (5) and SM3 (6) MUST now embed the private algorithm
identifier before the digest data if the DS algorithm field is
PRIVATEDNS or PRIVATEOID in the same manner as is done for the
matching DNSKEY record.
It is RECOMMENDED that only DS records with DS digest types that
embed the private DNSSEC algorithm are used with private DNSSEC
algorithms as allows for publishing of DS records without the
corresponding DNSKEY record being published.
3. New DS Types
New DS type identifiers which support embedding the private DNSSEC
algorithm identifier are needed for SHA-256, SHA-384, GOST R
34.11-2012 and SM3 are needed along with identifing names. The new
names and types are SHA-256-PRIVATE (TBA), SHA-384-PRIVATE (TBA),
GOST R 34.11-2012 PRIVATE (TBA) and SM3-PRIVATE (TBA) respectively.
4. IANA Considerations
IANA is requested to assign DS types for SHA-256-PRIVATE, SHA-
384-PRIVATE, GOST R 34.11-2012 PRIVATE and SM3-PRIVATE.
5. Security Considerations
This adds no known security issues.
6. 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>.
[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>.
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Appendix A. Example
Below we generate a example key using a PRIVATEOID DNSSEC algorithm
and generate DS records from it using the SHA-256 digest and the
proposed SHA-256-PRIVATE digest types. We also generate DS records
for a RSASHA256 key using the same digests for comparison. The
records have been converted to multi-line form for display purposes.
% dnssec-keygen -a RSASHA256OID example
Kexample.+256+40597
% dnssec-dsfromkey -a SHA-256 -a SHA-256-PRIVATE Kexample.+256+40597
example. IN DS 40597 254 2 ( D34C1ED54CC310D4DDECD935626B83A21E9462A
41519DCE3C7B88346B88E667D )
example. IN DS 40597 254 7 ( 0B06092A864886F70D01010BD34C1ED54CC310D
4DDECD935626B83A21E9462A41519DCE3C7B883
46B88E667D )
% cat Kexample.+256+40597.key
; This is a zone-signing key, keyid 40597, for example.
; Created: 20250530054504 (Fri May 30 15:45:04 2025)
; Publish: 20250530054504 (Fri May 30 15:45:04 2025)
; Activate: 20250530054504 (Fri May 30 15:45:04 2025)
example. IN DNSKEY 256 3 254 ( CwYJKoZIhvcNAQELAwEAAd3K9HIqJL+AiOb19
TPx/tgDbVVigJELn+LB6PqVD7U5tNPEYqVVK8
aRokyCd/Id/0l9xTVXDiDOCNVnTEZc6P20nhl
c1+alJF4S419APxE0EL8DAiiEAU4zwzLU41/4
1raFqN/sRZRLElvtEswtOXxvx5IGdAqnN0Np4
OiXMCmm4AoJ8RwCxWP2BNNp8CjRza3QaEk61/
ACc0U23Ol7wYefDudUoWJLKQFK6XM7pxuG5Zn
T4Hc0/Mbd3X/7Vi3zcxxef55v4jQEFxgXEIin
VlDtDVSSOGM+unPZeviedPqpCabVuUVPHOVyY
q/9OdCsHNZORdpo1nJuYVdwSs0t8AM= )
% dnssec-dsfromkey -a SHA-256 -a SHA-256-PRIVATE Kexample.+008+00163
example. IN DS 163 8 2 ( CAD5B47A4EA7D8F51926202CE4F89250C367D6EF2E0
8D8D26367056E7F76DE9A )
example. IN DS 163 8 7 ( CAD5B47A4EA7D8F51926202CE4F89250C367D6EF2E0
8D8D26367056E7F76DE9A )
%
Author's Address
M. Andrews
Internet Systems Consortium
PO Box 360
Newmarket, NH 03857
United States of America
Email: marka@isc.org
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