dnsop P. van Dijk Internet-Draft PowerDNS Intended status: Standards Track 4 November 2024 Expires: 8 May 2025 The VERBATIM Digest Algorithm for DS records draft-vandijk-dnsop-ds-digest-verbatim-02 Abstract The VERBATIM DS Digest is defined as a direct copy of the input data without any hashing. 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 8 May 2025. Copyright Notice Copyright (c) 2024 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. van Dijk Expires 8 May 2025 [Page 1] Internet-Draft ds-digest-verbatim November 2024 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Document work . . . . . . . . . . . . . . . . . . . . . . . . 2 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 . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. Implementation Status . . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 9. Normative References . . . . . . . . . . . . . . . . . . . . 4 10. Informative References . . . . . . . . . . . . . . . . . . . 4 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 some use cases for signed data at the parent, such an an oracle might not be sufficient. This document introduces a new Digest Algorithm, proposed name VERBATIM (alternative suggestions: NULL, IDENTITY). 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. 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. van Dijk Expires 8 May 2025 [Page 2] Internet-Draft ds-digest-verbatim November 2024 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. 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. van Dijk Expires 8 May 2025 [Page 3] Internet-Draft ds-digest-verbatim November 2024 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 [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, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . 10. Informative References van Dijk Expires 8 May 2025 [Page 4] Internet-Draft ds-digest-verbatim November 2024 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8499] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS Terminology", RFC 8499, DOI 10.17487/RFC8499, January 2019, . Appendix A. Document history Author's Address Peter van Dijk PowerDNS Den Haag Netherlands Email: peter.van.dijk@powerdns.com van Dijk Expires 8 May 2025 [Page 5]