



Network Working Group                                        W. Hardaker
Internet-Draft                                                    Google
Intended status: Best Current Practice                    5 January 2026
Expires: 9 July 2026


             Intentionally Temporarily Degraded or Insecure
         draft-hardaker-dnsop-intentionally-temporary-insec-02

Abstract

   Performing DNSKEY algorithm transitions with DNSSEC signing is
   unfortunately challenging to get right in practice without decent
   tooling support.  This document weighs the correct, completely secure
   way of rolling keys against an alternate, significantly simplified,
   method that takes a zone through an insecure state first.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 9 July 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   provided without warranty as described in the Revised BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements notation . . . . . . . . . . . . . . . . . .   3
   2.  Transitioning temporarily through insecurity  . . . . . . . .   3
   3.  Operational considerations  . . . . . . . . . . . . . . . . .   4
   4.  Security considerations . . . . . . . . . . . . . . . . . . .   5
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Acknowledgments  . . . . . . . . . . . . . . . . . .   7
   Appendix B.  Github Version of this document  . . . . . . . . . .   8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   Performing DNSKEY [RFC4035] algorithm transitions with DNSSEC
   [RFC4033] signing is unfortunately challenging to get right in
   practice without decent tooling support.  This document weighs the
   correct, completely secure way of rolling keys against an alternate,
   significantly simplified, method that takes a zone through an
   insecure state.

   Section 4.1.4 of [RFC6781] describes the necessary steps required
   when a new signing key is published for a zone that uses a different
   signing algorithm than the currently published keys.  These are the
   steps that MUST be followed when zone owners wish to have
   uninterrupted DNSSEC protection for their zones.  The steps in this
   document are designed to ensure that all DNSKEY records and all DS
   [RFC4509] records (and the rest of a zone records) are properly
   validatable by validating resolvers throughout the entire process.
   Whenever possible, this procedure SHOULD be followed.

   Unfortunately, there are a number of these steps that are challenging
   to accomplish either because the timing is tricky to get right or
   because current software doesn't support automating the process
   easily.  Some examples:

   1.  The second step in Section 4.1.4 of [RFC6781] requires that a new
       key with the new algorithm (which we refer to as K_new) be
       created, but not yet published.  This step requires that both the
       old key (K_old) and K_new both sign and generate signatures for
       the zone, but without K_new actually being published in the zone
       even though its signatures.  Put another way, only K_old can
       exist in the zone even though signatures from both keys must be
       included.  After this odd mix has been published for a sufficient
       time length, based on the TTL, can K_new be safely introduced and
       published into the zone as well.



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   2.  Sometimes one of the goals is to transfer zone management to new
       authoritative server software.  But, if the newly desired
       algorithm isn't supported in the existing (to be replaced) DNSSEC
       signing software, then the transfer to the new software must be
       accomplished first.  However, if there isn't an overlap between
       the algorithms available in both software sets, it becomes
       practically impossible to even transfer the zone since neither
       software set can use both K_old and K_new.

   Although some DNSSEC signing solutions may automate the algorithm
   rollover steps (making operator involvement unnecessary), many other
   tools do not yet support automated algorithm updates.  In these
   environments, the most challenging step is requiring that certain
   RRSIGs be published without the corresponding DNSKEYs that created
   them.  This will likely require operators to use a text editor on the
   contents of a signed zone to carefully select zone records to extract
   before publication.  This introduces potentially significant operator
   error(s).

   This document proposes an alternate approach that MAY be used to
   perform algorithm DNSKEY rollovers in these situations, which is
   potentially more operationally robust but less secure.

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.  Transitioning temporarily through insecurity

   An alternate approach to properly rolling DNSKEYs to a new algorithm,
   is to intentionally make the zone become insecure while the DNSKEYs
   and algorithms are swapped.  At a high level, this means removing all
   DS records from the parent zone first, then remove the old key and
   introduce the new key with its new algorithm during this period.
   Zone TTLs can be significantly shortened during this period to
   minimize the period of insecurity.

   Below are the enumerated steps required by this alternate transition
   mechanism.  Note that there are still two critical waiting time
   requirements (steps 2 and 6) that must be followed carefully.

   1.  Optional: lower the TTLs of both the zone's DS record, and the
       TTL of the DNSKEY RRset.  Note that in some operational
       deployments the parent zone may set the TTL of the DS record.



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   2.  Remove all DS records from the parent zone.

   3.  Ensure the zone is considered unsigned by all validating
       resolvers by waiting 2 times the maximum TTL length for the DS
       record, and/or 2 times the largest TTL found in the zone
       (whichever is larger).  This is the most critical timing as all
       records associated with K_old must be cleared from validating
       resolver caches.  (The author of this document failed to wait the
       required time once.  It was not pretty.)

   4.  Replace the old DNSKEY(s) using the old algorithm with new
       DNSKEY(s) using the new algorithm(s) in the zone and publish the
       zone.

   5.  Wait 2 times the largest TTL found in the zone to ensure the new
       DNSKEYs will be found by validating resolvers.

   6.  Add the DS record(s) for the new DNSKEYs to the parent zone.

   7.  If the TTLs were modified in the optional step 1, change them
       back to their preferred values.

3.  Operational considerations

   The process of replacing a DNSKEY with an older algorithm [RFC9904],
   such as RSAMD5 [RFC4034] or RSASHA1 [RFC9905] with a more modern one
   [RFC9904] such as RSASHA512 [RFC5702] or ECDSAP256SHA256 [RFC6605]
   can be a daunting task if the zone's current tooling doesn't provide
   an easy-to-use solution.  For example, this may be the case for zone
   owners using command line tools integrated into their zone production
   environment.

   This document describes an alternative approach to rolling DNSKEY
   algorithms that may be significantly less prone to operational
   mistakes.  However, it is paramount that operators understand of the
   security considerations of using this approach.

   The document recommends waiting 2 times TTL values in certain cases
   for added assurance that the waiting period is long enough for caches
   to expire.  In reality, waiting slightly longer than 1 TTL may be
   sufficient but requires accepting added risks with propagation timing
   and clock synchronization.









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4.  Security considerations

   DNSSEC provides data integrity protection for DNS data.  This
   document specifically calls out a reason why a zone owner may desire
   to deliberately turn off this protection while changing the zone's
   DNSKEY's cryptographic algorithms.  Thus, this technique is
   potentially harmful if an attacker knows when this will occur and can
   use that time window to launch DNS modification attacks (for example,
   cache poisoning attacks) against validating resolvers or other
   validating DNS infrastructure.

   Most importantly, this will deliberately break certain types of DNS
   records that must be validatable for them to be effective.  This
   includes for example, but not limited to, all DS records for the
   zone's own children, DANE [RFC6698][RFC7671][RFC7672], PGP key
   fingerprints [RFC7929], and SSHFP[RFC4255] fingerprints.  Zone owners
   must carefully consider which records within their zone and their
   zone's children depend on DNSSEC being available before using the
   procedure outlined in this document.

   Given all of this, it leaves the question of: "why would a zone owner
   want to deliberately turn off security temporarily then?", to which
   there is one principal answer: if the the complexity of executing an
   algorithm role the correct way is difficult (or impossible), then the
   chances of introducing an error that causes an operational outage may
   be significantly higher than the chances of the zone being attacked
   during the insecure transition period.  Simply put, an invalid zone
   created by a botched algorithm roll is potentially worse than an
   unsigned but still available zone.

5.  References

5.1.  Normative References

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/rfc/rfc1035>.

   [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/rfc/rfc2119>.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements",
              RFC 4033, DOI 10.17487/RFC4033, March 2005,
              <https://www.rfc-editor.org/rfc/rfc4033>.




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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/rfc/rfc4034>.

   [RFC4035]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "Protocol Modifications for the DNS Security
              Extensions", RFC 4035, DOI 10.17487/RFC4035, March 2005,
              <https://www.rfc-editor.org/rfc/rfc4035>.

   [RFC4509]  Hardaker, W., "Use of SHA-256 in DNSSEC Delegation Signer
              (DS) Resource Records (RRs)", RFC 4509,
              DOI 10.17487/RFC4509, May 2006,
              <https://www.rfc-editor.org/rfc/rfc4509>.

   [RFC6781]  Kolkman, O., Mekking, W., and R. Gieben, "DNSSEC
              Operational Practices, Version 2", RFC 6781,
              DOI 10.17487/RFC6781, December 2012,
              <https://www.rfc-editor.org/rfc/rfc6781>.

   [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/rfc/rfc8174>.

5.2.  Informative References

   [RFC4255]  Schlyter, J. and W. Griffin, "Using DNS to Securely
              Publish Secure Shell (SSH) Key Fingerprints", RFC 4255,
              DOI 10.17487/RFC4255, January 2006,
              <https://www.rfc-editor.org/rfc/rfc4255>.

   [RFC5702]  Jansen, J., "Use of SHA-2 Algorithms with RSA in DNSKEY
              and RRSIG Resource Records for DNSSEC", RFC 5702,
              DOI 10.17487/RFC5702, October 2009,
              <https://www.rfc-editor.org/rfc/rfc5702>.

   [RFC6605]  Hoffman, P. and W.C.A. Wijngaards, "Elliptic Curve Digital
              Signature Algorithm (DSA) for DNSSEC", RFC 6605,
              DOI 10.17487/RFC6605, April 2012,
              <https://www.rfc-editor.org/rfc/rfc6605>.

   [RFC6698]  Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
              of Named Entities (DANE) Transport Layer Security (TLS)
              Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
              2012, <https://www.rfc-editor.org/rfc/rfc6698>.






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   [RFC7671]  Dukhovni, V. and W. Hardaker, "The DNS-Based
              Authentication of Named Entities (DANE) Protocol: Updates
              and Operational Guidance", RFC 7671, DOI 10.17487/RFC7671,
              October 2015, <https://www.rfc-editor.org/rfc/rfc7671>.

   [RFC7672]  Dukhovni, V. and W. Hardaker, "SMTP Security via
              Opportunistic DNS-Based Authentication of Named Entities
              (DANE) Transport Layer Security (TLS)", RFC 7672,
              DOI 10.17487/RFC7672, October 2015,
              <https://www.rfc-editor.org/rfc/rfc7672>.

   [RFC7929]  Wouters, P., "DNS-Based Authentication of Named Entities
              (DANE) Bindings for OpenPGP", RFC 7929,
              DOI 10.17487/RFC7929, August 2016,
              <https://www.rfc-editor.org/rfc/rfc7929>.

   [RFC9904]  Hardaker, W. and W. Kumari, "DNSSEC Cryptographic
              Algorithm Recommendation Update Process", RFC 9904,
              DOI 10.17487/RFC9904, November 2025,
              <https://www.rfc-editor.org/rfc/rfc9904>.

   [RFC9905]  Hardaker, W. and W. Kumari, "Deprecating the Use of SHA-1
              in DNSSEC Signature Algorithms", RFC 9905,
              DOI 10.17487/RFC9905, November 2025,
              <https://www.rfc-editor.org/rfc/rfc9905>.

Appendix A.  Acknowledgments

   The author has discussed the pros and cons of this approach with
   multiple people, including:

   *  Vladimír Čunát

   *  Peter van Dijk

   *  Viktor Dukhovni

   *  Warren Kumari.

   *  Scott Rose

   *  Tuomo Soini

   *  Paul Wouters







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Appendix B.  Github Version of this document

   While this document is under development, it can be viewed, tracked,
   issued, pushed with PRs, ... here:

   https://github.com/hardaker/draft-hardaker-dnsop-intentionally-
   temporarily-insecure

Author's Address

   Wes Hardaker
   Google
   Email: ietf@hardakers.net






































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