| Internet-Draft | DS support for private DNSSEC algorithms | May 2025 |
| Andrews | Expires 2 December 2025 | [Page] |
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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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.¶
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 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.¶
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.¶
IANA is requested to assign DS types for SHA-256-PRIVATE, SHA-384-PRIVATE, GOST R 34.11-2012 PRIVATE and SM3-PRIVATE.¶
This adds no known security issues.¶
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 )
%
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