Internet-Draft MUST NOT DNSSEC with SHA-1 August 2022
Hardaker Expires 13 February 2023 [Page]
Network Working Group
Intended Status:
Standards Track
W. Hardaker

Remove SHA-1 from active use within DNSSEC


This document retires the use of SHA-1 within DNSSEC

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

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This Internet-Draft will expire on 13 February 2023.

Table of Contents

1. Introduction

The security of the SHA-1 algorithm [RFC3174] has been slowly diminishing over time as various forms of attacks have weakened its cryptographic underpinning. DNSSEC [RFC4033] [RFC4034] [RFC4035] originally made extensive use of SHA-1 as a cryptographic verification algorithm in RRSIG and Delegation Signer (DS) records, for example. Since then, multiple other signing algorithms with stronger cryptographic strength are now widely available for DS records (such as SHA-256 [RFC4509], SHA-384 ([RFC6605])) and for DNSKEY and RRSIG records (such as RSASHA256 ([RFC5702]), RSASHA512 ([RFC5702]), ECDSAP256SHA256 [RFC6605], ECDSAP384SHA384 [RFC6605], ED25519 [RFC8080], and ED448 [RFC8080]), the use of SHA-1 is no longer needed.

This document retires the use of SHA-1 within DNSSEC.

1.1. Requirements notation

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.

2. Deprecating SHA-1 algorithms in DNSSEC

The SHA-1 [RFC3685] algorithm MUST NOT be used when creating DS records.

The RSASHA1 [RFC4034], DSA-NSEC3-SHA1 [RFC5155], and RSASHA1-NSEC3-SHA1 [RFC5155] algorithms MUST NOT be used when creating DNSKEY and RRSIG records.

3. Security Considerations

This document increases the security of the DNSSEC ecosystem by deprecating algorithms that make use of older algorithms with SHA-1 derived uses.

4. Operational Considerations

Zone owners currently making use of SHA-1 based algorithms should immediate switch to algorithms with stronger cryptographic strengths, such as those listed in the introduction. DNS registries [RFC8499] should prohibit their clients to upload and publish SHA-1 based DS records.

5. IANA Considerations

IANA is requested to mark the following Delegation Signer (DS) Resource Record (RR) digest type algorithms as deprecated:

IANA is requested to mark the following DNS Security Algorithm Numbers as deprecated:

6. References

6.1. Normative References

Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Eastlake 3rd, D. and P. Jones, "US Secure Hash Algorithm 1 (SHA1)", RFC 3174, DOI 10.17487/RFC3174, , <>.
Daboo, C., "SIEVE Email Filtering: Spamtest and VirusTest Extensions", RFC 3685, DOI 10.17487/RFC3685, , <>.
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "DNS Security Introduction and Requirements", RFC 4033, DOI 10.17487/RFC4033, , <>.
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Resource Records for the DNS Security Extensions", RFC 4034, DOI 10.17487/RFC4034, , <>.
Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC 4035, DOI 10.17487/RFC4035, , <>.
Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer (DS) Resource Records (RRs)", RFC 4509, DOI 10.17487/RFC4509, , <>.
Laurie, B., Sisson, G., Arends, R., and D. Blacka, "DNS Security (DNSSEC) Hashed Authenticated Denial of Existence", RFC 5155, DOI 10.17487/RFC5155, , <>.
Jansen, J., "Use of SHA-2 Algorithms with RSA in DNSKEY and RRSIG Resource Records for DNSSEC", RFC 5702, DOI 10.17487/RFC5702, , <>.
Hoffman, P. and W.C.A. Wijngaards, "Elliptic Curve Digital Signature Algorithm (DSA) for DNSSEC", RFC 6605, DOI 10.17487/RFC6605, , <>.
Sury, O. and R. Edmonds, "Edwards-Curve Digital Security Algorithm (EdDSA) for DNSSEC", RFC 8080, DOI 10.17487/RFC8080, , <>.

6.2. Informative References

Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499, , <>.

Appendix A. Acknowledgments


Appendix B. Current algorithm usage levels

The DNSSEC scanning project by Viktor Dukhovni and Wes Hardaker highlights the current deployment of various algorithms on the website.

[RFC Editor: please delete this section upon publication]

Appendix C. Github Version of this document

While this document is under development, it can be viewed, tracked, fill here:

Author's Address

Wes Hardaker