Post-Quantum Cryptography Strategy for DNSSEC
draft-sheth-pqc-dnssec-strategy-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Swapneel Sheth , Taejoong Chung , Benno Overeinder | ||
| Last updated | 2025-10-16 | ||
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| Intended RFC status | (None) | ||
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draft-sheth-pqc-dnssec-strategy-00
Network Working Group S. Sheth
Internet-Draft Verisign Labs
Intended status: Informational T. Chung
Expires: 19 April 2026 Virginia Tech
B. Overeinder
NLnet Labs
16 October 2025
Post-Quantum Cryptography Strategy for DNSSEC
draft-sheth-pqc-dnssec-strategy-00
Abstract
This document proposes a post-quantum cryptography (PQC) strategy for
Domain Name System Security (DNSSEC) that includes two types of
algorithms: one or more conservatively designed algorithms that are
unlikely ever to need to be replaced, and one or more low-impact
drop-in algorithms that are used the same way as a traditional
signature algorithm. The conservatively designed algorithms can be
used in a mode of operation that mitigates the operational impact of
a large signature size. The combination provides both the routine
performance of the low-impact algorithm and a resilient fallback to
the conservatively designed choice. The draft outlines the strategy,
provides recommendations for future testing and deployment, and
highlights operational considerations in adopting PQC for 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
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 19 April 2026.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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Table of Contents
1. Conventions Used in This Document . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Post-Quantum DNSSEC Challenges . . . . . . . . . . . . . . . 3
3.1. Operational Constraints . . . . . . . . . . . . . . . . . 3
3.2. Deployment Cycles . . . . . . . . . . . . . . . . . . . . 3
4. Proposed PQC Algorithm Diversity Strategy . . . . . . . . . . 3
4.1. Mode of Operation . . . . . . . . . . . . . . . . . . . . 4
5. Alternatives and Considerations . . . . . . . . . . . . . . . 4
6. Recommended Next Steps . . . . . . . . . . . . . . . . . . . 4
7. Current Community Efforts . . . . . . . . . . . . . . . . . . 4
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . 6
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Conventions Used in This Document
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. Introduction
DNSSEC [RFC4034][RFC4035][RFC9364] provides data origin
authentication for DNS resource records. Current algorithms, such as
RSASHA256 (8) and ECDSA (13), are vulnerable to cryptanalytically
capable quantum computers. While "harvest now/decrypt later" is not
a concern for DNSSEC, as it is for some other protocols such as TLS,
"trust now/forge later" is a concern for DNSSEC. Ensuring that
signatures are valid and secure from inception until expiration is
critical. This combined with the fact that standards bodies like the
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National Institute of Standards and Technology (NIST) are deprecating
support for classical algorithms ensures that migration to post-
quantum cryptography (PQC) is necessary. Unfortunately, migration
with the large signature sizes introduce operational risks.
This draft proposes a strategy deploying:
* One or more conservatively designed PQC algorithm in a mode
mitigating large signature sizes.
* One or more low-impact drop-in PQC algorithm analogous to
traditional DNSSEC signatures.
This dual-algorithm approach ensures routine performance and
resilient fallback during PQC transition.
This draft is intended as a contribution to ongoing algorithm updates
and the algorithm lifecycle per drafts [I-D.ietf-dnsop-rfc8624-bis]
and[I-D.crocker-dnsop-dnssec-algorithm-lifecycle]
3. Post-Quantum DNSSEC Challenges
3.1. Operational Constraints
DNS primarily runs over UDP, with packet sizes limited to a maximum
of ~1232 bytes. Traditional signatures (e.g., RSASHA256, ECDSA) fit
within this limit. PQC signatures (ML-DSA: 2420-4627 bytes, SLH-DSA:
7856-49856 bytes) exceed it, risking excessive TCP fallback, latency,
and resolver performance degradation [Sury2025].
3.2. Deployment Cycles
DNSSEC upgrades occur over years. Novel PQC algorithms may face
uncertain adoption timelines, requiring fallback mechanisms. Some
algorithms (e.g., SQIsign) impose verification overhead, slowing
response times [Sury2025].
4. Proposed PQC Algorithm Diversity Strategy
DNSSEC should deploy two types of PQC signature algorithms:
Currently standardized post-quantum secure algorithms that provide
cryptographic confidence and resilient fallback. Examples: SLH-DSA
in Merkle Tree Ladder (MTL) mode [I-D.harvey-cfrg-mtl-mode],
Falcon[FALCON], XMSS[RFC8391], LMS[RFC8554].
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New algorithms such as the ones that remain under NIST onramp
evaluation or under consideration by other standards bodies. These
provide routine performance with minimal operational impact. They
may leverage newer but less well-established mathematical concepts.
Examples: MAYO[MAYO], SNOVA[SNOVA].
4.1. Mode of Operation
MTL mode signs a Merkle tree ladder rather than individual DNS
responses, amortizing signature size across multiple responses
[Fregly2023]. In DNSSEC, this reduces operational impact while
maintaining security[I-D.fregly-dnsop-slh-dsa-mtl-dnssec].
5. Alternatives and Considerations
* Conservative candidates: SLH-DSA, ML-DSA (possibly combined with
traditional algorithms), Falcon, XMSS, LMS.
* Low-impact candidates: New algorithms such as the ones that remain
under NIST onramp evaluation or under consideration by other
standards bodies.
* Use of modes of operation (like MTL mode) to mitigate large
signature sizes.
6. Recommended Next Steps
* Conduct hackathons testing multiple algorithms in BIND, NSD, and
CoreDNS (see current progress in Section 7).
* Measure latency, fallback rates, and resilience under adversarial
conditions, including KeyTrap-style attacks [HeBrig2024].
* Research countermeasures against denial-of-service risks for MTL
mode.
7. Current Community Efforts
Several efforts are underway to implement, test, and discuss PQC
algorithms in DNSSEC.
* IETF PQC DNSSEC Side Meeting - https://wiki.ietf.org/en/group/pq-
dnssec
* IETF 123 Hackathon - PQC DNSSEC Implementation [HACAKTHON-123]
* IETF 122 Hackathon - PQC for DNSSEC - New Kids on the Block
[HACAKTHON-122-NEW]
* IETF 122 Hackathon - PQC DNSSEC Metrics with MTL Mode
[HACAKTHON-122-MTL]
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8. IANA Considerations
This document makes no requests of IANA. Future work may include
registration of new DNSSEC algorithm codes for PQC algorithms.
9. Security Considerations
The deployment of PQC algorithms strengthens DNSSEC against quantum
attacks but introduces operational risks. Proper testing, fallback
mechanisms, and mode-of-operation considerations are essential to
avoid new vulnerabilities.
Continued community participation in PQC DNSSEC research, in
particular around low-impact drop-in algorithms, is essential to
standarizing secure PQC DNSSEC solutions. Additional considerations
will be described based on continued analysis and feedback.
10. References
10.1. Normative References
[I-D.crocker-dnsop-dnssec-algorithm-lifecycle]
Crocker, S. and R. Housley, "Documenting and Managing
DNSSEC Algorithm Lifecycles", Work in Progress, Internet-
Draft, draft-crocker-dnsop-dnssec-algorithm-lifecycle-01,
4 October 2024, <https://datatracker.ietf.org/doc/html/
draft-crocker-dnsop-dnssec-algorithm-lifecycle-01>.
[I-D.ietf-dnsop-rfc8624-bis]
Hardaker, W. and W. Kumari, "DNSSEC Cryptographic
Algorithm Recommendation Update Process", Work in
Progress, Internet-Draft, draft-ietf-dnsop-rfc8624-bis-13,
4 June 2025, <https://datatracker.ietf.org/doc/html/draft-
ietf-dnsop-rfc8624-bis-13>.
[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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[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/info/rfc4035>.
[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/info/rfc8174>.
[RFC9364] Hoffman, P., "DNS Security Extensions (DNSSEC)", BCP 237,
RFC 9364, DOI 10.17487/RFC9364, February 2023,
<https://www.rfc-editor.org/info/rfc9364>.
10.2. Informative References
[FALCON] Fouque, P., Hoffstein, J., Kirchner, P., Lyubashevsky, V.,
Pornin, T., Prest, T., Ricosset, T., Seiler, G., Whyte,
W., and Z. Zhang, "Falcon: Fast-Fourier Lattice-based
Compact Signatures over NTRU", 10 January 2020,
<https://falcon-sign.info/falcon.pdf>.
[Fregly2023]
Fregly, A., Harvey, J., Kaliski, B., and S. Sheth, "Merkle
Tree Ladder Mode: Reducing the Size Impact of NIST PQC
Signature Algorithms in Practice", 2022,
<https://eprint.iacr.org/2022/1730>.
[HACAKTHON-122-MTL]
Harvey, J. and S. Sheth, "IETF 122 - PQC DNSSEC Metrics
with MTL Mode", 16 March 2025,
<https://datatracker.ietf.org/meeting/122/materials/
slides-122-hackathon-sessd-pqc-dnssec-metrics-with-mtl-
mode-00>.
[HACAKTHON-122-NEW]
Sury, O., "PQC for DNSSEC - New Kids on the Block", 16
March 2025,
<https://datatracker.ietf.org/meeting/122/materials/
slides-122-hackathon-sessd-pqc4dnssec-00>.
[HACAKTHON-123]
Jimenez-Berenguel, A., Harvey, J., Blanco-Romero, J.,
Sheth, S., Sury, O., and W. Toorop, "IETF 123 - PQC DNSSEC
Implementation", July 2025,
<https://datatracker.ietf.org/meeting/123/materials/
slides-123-hackathon-sessd-ietf-123-pqc-dnssec-
implementation-00>.
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[HeBrig2024]
Heftrig, E., Schulmann, H., Vogel, N., and M. Waidner,
"The Harder You Try, The Harder You Fail: The KeyTrap
Denial-of-Service Algorithmic Complexity Attacks on
DNSSEC", 2024, <https://arxiv.org/abs/2406.03133>.
[I-D.fregly-dnsop-slh-dsa-mtl-dnssec]
Fregly, A., Harvey, J., Kaliski, B., and D. Wessels,
"Stateless Hash-Based Signatures in Merkle Tree Ladder
Mode (SLH-DSA-MTL) for DNSSEC", Work in Progress,
Internet-Draft, draft-fregly-dnsop-slh-dsa-mtl-dnssec-05,
30 September 2025, <https://datatracker.ietf.org/doc/html/
draft-fregly-dnsop-slh-dsa-mtl-dnssec-05>.
[I-D.harvey-cfrg-mtl-mode]
Harvey, J., Kaliski, B., Fregly, A., and S. Sheth, "Merkle
Tree Ladder (MTL) Mode Signatures", Work in Progress,
Internet-Draft, draft-harvey-cfrg-mtl-mode-07, 9 September
2025, <https://datatracker.ietf.org/doc/html/draft-harvey-
cfrg-mtl-mode-07>.
[MAYO] Beullens, W., Campos, F., Celi, S., Hess, B., and M.
Kannwischer, "MAYO", 5 February 2025,
<https://pqmayo.org/assets/specs/mayo-round2.pdf>.
[RFC8391] Huelsing, A., Butin, D., Gazdag, S., Rijneveld, J., and A.
Mohaisen, "XMSS: eXtended Merkle Signature Scheme",
RFC 8391, DOI 10.17487/RFC8391, May 2018,
<https://www.rfc-editor.org/info/rfc8391>.
[RFC8554] McGrew, D., Curcio, M., and S. Fluhrer, "Leighton-Micali
Hash-Based Signatures", RFC 8554, DOI 10.17487/RFC8554,
April 2019, <https://www.rfc-editor.org/info/rfc8554>.
[SNOVA] Wang, L., Chou, C., Ding, J., Kuan, Y., Leegwater, J., Li,
M., Tseng, B., Tseng, P., and C. Wang, "SNOVA Proposal for
NISTPQC: Additional Digital Signature Schemes", 25 January
2025, <https://csrc.nist.gov/csrc/media/Projects/pqc-dig-
sig/documents/round-2/spec-files/snova-spec-
round2-web.pdf>.
[Sury2025] Sury, O., "Feasibility of the new Post Quantum
Cryptography for DNSSEC", 2025,
<https://typst.app/project/rJ0w6uUpoHWo6Pjd1fbUx6>.
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Acknowledgements
Thanks to Andrew Fregly for early contributions in promoting PQ
DNSSEC and uniting the research community around a post-quantum
research agenda.
Change Log
00: Initial draft of the document.
Authors' Addresses
Swapneel Sheth
Verisign Labs
12061 Bluemont Way
Reston, VA 20190
United States of America
Email: ssheth@verisign.com
URI: https://www.verisignlabs.com/
Taejoong Chung
Virginia Tech
220 Gilbert Street, RM 4303
Blacksburg, VA 24060
United States of America
Email: tijay@vt.edu
URI: https://www.vt.edu/
Benno Overeinder
NLnet Labs
Science Park 400
1098 XH Amsterdam
Netherlands
Email: benno@nlnetlabs.nl
URI: https://nlnetlabs.nl
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