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Post-Quantum Signature Algorithm Profile and Migration Considerations for the Resource Public Key Infrastructure (RPKI)
draft-yoshikawa-sidrops-pqc-rpki-01

Document Type Active Internet-Draft (individual)
Author Tomoki Yoshikawa
Last updated 2026-07-03
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draft-yoshikawa-sidrops-pqc-rpki-01
SIDROPS                                                     T. Yoshikawa
Internet-Draft          Graduate School of Informatics, Kyoto University
Intended status: Standards Track                             4 July 2026
Expires: 5 January 2027

 Post-Quantum Signature Algorithm Profile and Migration Considerations
           for the Resource Public Key Infrastructure (RPKI)
                  draft-yoshikawa-sidrops-pqc-rpki-01

Abstract

   This document defines an initial experimental post-quantum signature
   profile and migration design for the Resource Public Key
   Infrastructure (RPKI).  The profile uses Composite ML-DSA-65 with
   ECDSA P-256 for RPKI certificates, CRLs, certification requests, and
   CMS signed objects.  The migration design introduces the composite
   suite at CA boundaries through Mixed Certification Chains.  It
   preserves the existing RPKI object formats, repository system,
   validation procedure, and router-facing VRP/RTR model.  This revision
   is intended for SIDROPS evaluation and does not update RFC 7935.

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 5 January 2027.

Copyright Notice

   Copyright (c) 2026 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

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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Design Goals  . . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Algorithm Profile . . . . . . . . . . . . . . . . . . . . . .   5
     6.1.  Current Suite . . . . . . . . . . . . . . . . . . . . . .   5
     6.2.  Primary Experimental Candidate  . . . . . . . . . . . . .   5
     6.3.  Additional Candidate Suites . . . . . . . . . . . . . . .   6
     6.4.  Classical Reference Points  . . . . . . . . . . . . . . .   7
     6.5.  Algorithm Comparison  . . . . . . . . . . . . . . . . . .   7
     6.6.  Algorithm Selection Rationale . . . . . . . . . . . . . .   8
   7.  Resource Certificate and CRL Profile  . . . . . . . . . . . .  10
   8.  CMS Signed Object Profile . . . . . . . . . . . . . . . . . .  11
   9.  Signed Object Coverage  . . . . . . . . . . . . . . . . . . .  11
   10. Manifests and Repository Processing . . . . . . . . . . . . .  12
     10.1.  Manifest Scope During Migration  . . . . . . . . . . . .  12
     10.2.  Parallel Publication Mechanics . . . . . . . . . . . . .  12
   11. Relying Party Behavior  . . . . . . . . . . . . . . . . . . .  13
   12. Migration Considerations  . . . . . . . . . . . . . . . . . .  14
     12.1.  Parallel Publication and Semantic Divergence . . . . . .  14
     12.2.  Composite Signatures . . . . . . . . . . . . . . . . . .  14
     12.3.  Mixed Certification Chains and Mixed-Tree Migration  . .  15
   13. Implementation Status . . . . . . . . . . . . . . . . . . . .  15
   14. Security Considerations . . . . . . . . . . . . . . . . . . .  17
   15. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  19
   16. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .  19
     16.1.  Algorithm Selection  . . . . . . . . . . . . . . . . . .  19
     16.2.  Migration Design . . . . . . . . . . . . . . . . . . . .  19
     16.3.  Operational Readiness  . . . . . . . . . . . . . . . . .  20
   17. Normative References  . . . . . . . . . . . . . . . . . . . .  20
   18. Informative References  . . . . . . . . . . . . . . . . . . .  22
   Appendix A.  Preliminary Measurement Results  . . . . . . . . . .  24
     A.1.  Measured Certificate and CRL Sizes  . . . . . . . . . . .  24
     A.2.  Synthetic Repository Size Model . . . . . . . . . . . . .  25
     A.3.  Bulk Signing and Verification . . . . . . . . . . . . . .  26
     A.4.  Open Measurement Tasks  . . . . . . . . . . . . . . . . .  27
   Appendix B.  Changes from -00 . . . . . . . . . . . . . . . . . .  28
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .  28
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  29

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1.  Introduction

   The RPKI relies on digital signatures in resource certificates, CRLs,
   certification requests, and CMS signed objects such as manifests and
   Route Origin Authorizations (ROAs).  The deployed RPKI algorithm
   profile is based on RSA with SHA-256.  A Cryptographically Relevant
   Quantum Computer (CRQC) would invalidate the long-term security
   assumptions of the classical signature algorithms used today.  This
   document therefore describes a migration path away from CRQC-
   vulnerable signature algorithms that can be tested before an
   emergency transition is required.

   The design goal of this document is conservative.  RPKI already has a
   well-defined architecture, repository system, validation procedure,
   and router interface.  This document keeps those layers intact.  PQC
   processing is introduced at the Certification Authority (CA),
   repository, CMS signed object, and Relying Party (RP) validation
   layers.  Routers that consume Validated ROA Payloads (VRPs) through
   the RPKI-Router Protocol (RTR) or local files are not expected to
   process PQC signatures directly.

2.  Requirements Language

   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 [BCP14] when, and only when, they appear in all capitals, as shown
   here.

3.  Terminology

   This document uses the terminology of the RPKI architecture
   [RFC6480], the resource certificate profile [RFC6487], the RPKI
   signed object template [RFC6488], the RPKI algorithm agility
   procedure [RFC6916], and the RPKI algorithm profile [RFC7935].

   Current Suite: The algorithm suite currently accepted by an RPKI
   implementation for production validation.  At the time of writing
   this is RSA-2048/SHA-256 as profiled by RFC 7935.

   Next Suite: A candidate algorithm suite that is implemented and
   tested before it becomes the Current Suite.

   PQC Suite: A Next Suite whose signature algorithm is intended to
   remain secure against a CRQC.

   Certificate Signature Algorithm: The algorithm used by the issuer to
   sign a certificate or CRL.

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   Subject Public Key Algorithm: The algorithm of the key carried in a
   certificate's subjectPublicKeyInfo (SPKI).

   Mixed Certification Chain: A certification path in which different
   algorithm suites are used above and below a transition certificate.

   Corresponding Products: RPKI products issued under different
   algorithm suites that assert the same RPKI semantics.  For ROAs, this
   means the same set of VRPs, modulo local policy and trust anchor
   selection.

   Semantic Equivalence: A property of two validated RPKI outputs in
   which their routing semantics are identical.  For ROA-derived VRPs,
   the comparison keys are prefix, maxLength, origin AS, and validation
   source or trust anchor context.  See also the Canonical Cache
   Representation [I-D.ietf-sidrops-rpki-ccr].

   Parallel Publication: A migration technique in which a CA publishes
   corresponding products under both the Current Suite and the Next
   Suite for an extended interval.

   Composite Signature: A single signature algorithm construction that
   combines a PQC algorithm and a traditional algorithm at the
   cryptographic or encoding layer.  Verification succeeds only when
   every component signature validates.

4.  Scope

   This document applies to RPKI resource certificates, CRLs,
   certification requests, BGPsec Router Certificates [RFC8209], and the
   CMS signed objects that reuse the RPKI signed object template
   [RFC6488], including manifests [RFC9286], ROAs [RFC9582], Signed
   Checklists (RSC) [RFC9323], ASPA objects
   [I-D.ietf-sidrops-aspa-profile], and Trust Anchor Key (TAK) objects
   [RFC9691].  The CMS signed objects are treated as a single signed-
   object algorithm profile; see the Signed Object Coverage section.

   This document covers the RPKI signatures on BGPsec Router
   Certificates, but does not define or change the BGPsec UPDATE
   signature algorithm specified by [RFC8608].

   This document does not specify changes to RTR, TAL formats, RRDP
   [RFC8182], rsync, the RPKI Certificate Policy, or the BPKI used to
   authenticate provisioning and publication relationships established
   through [RFC8183].  Readiness for BPKI trust-anchor key rollover is
   nevertheless a migration dependency and is recorded as an Open Issue.

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5.  Design Goals

   The profile has the following goals.

   *  Preserve the existing RPKI architecture and repository model.

   *  Reuse existing LAMPS PKIX and CMS encodings for PQC algorithms.

   *  Avoid new RPKI object formats unless measurements show that simple
      signature substitution is infeasible.

   *  Keep routers as consumers of validated payloads, not PQC
      validators, while acknowledging that RP validation and repository
      processing change.

   *  Apply one signature algorithm suite uniformly to all RFC 6488
      signed objects rather than per-object-type algorithm choices.

   *  Preserve signature unforgeability if one component of the
      composite suite is broken while the other component remains
      secure.

   *  Support a prolonged Current Suite and Next Suite interval.

   *  Make downgrade, unsupported-algorithm, and semantic-divergence
      cases observable by RPs and operators.

   *  Keep measurement and interoperability evidence reproducible
      outside the protocol specification.

6.  Algorithm Profile

6.1.  Current Suite

   The Current Suite remains RSA PKCS #1 v1.5 with SHA-256 as specified
   by RFC 7935 until a separate transition timetable changes production
   RPKI policy.

6.2.  Primary Experimental Candidate

   The primary Next Suite candidate in this revision is id-MLDSA65-
   ECDSA-P256-SHA512, as specified by [I-D.ietf-lamps-pq-composite-sigs]
   and [I-D.ietf-lamps-cms-composite-sigs].  It combines ML-DSA-65 with
   ECDSA P-256 and requires both component signatures to validate.  This
   revision selects the composite construction and Mixed Certification
   Chain as its migration design; deployment remains experimental until
   CA and RP interoperability is demonstrated.

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   An implementation experiment SHOULD process the composite public key
   and certificate signatures according to
   [I-D.ietf-lamps-pq-composite-sigs] and SHOULD process composite CMS
   SignedData according to [I-D.ietf-lamps-cms-composite-sigs].

   RPKI CAs participating in an isolated experiment MAY use the primary
   composite suite for CA certificates, EE certificates, CRLs, and CMS
   signed objects.  They MUST NOT publish experimental objects into a
   production repository or use production keys or TALs.

6.3.  Additional Candidate Suites

   ML-DSA-44 is a serious alternative to ML-DSA-65.  It produces smaller
   public keys and signatures and may sign and verify faster, which
   matters in a system where every RP repeatedly fetches and validates
   the entire global repository.  It is not the selected PQC component
   in this revision because this document currently uses NIST security
   Category 3 as a conservative floor for a long-lived, globally
   deployed suite; the Algorithm Selection Rationale discusses this
   trade-off and the counterarguments.

   ML-DSA-87 is included as a higher-security comparison candidate.  It
   is more conservative than ML-DSA-65 but carries correspondingly
   larger size and performance costs.

   SLH-DSA-SHAKE-128s and SLH-DSA-SHAKE-192s are included for
   cryptographic-diversity comparison.  Their primitive, PKIX, and CMS
   specifications are defined by [FIPS205], [RFC9909], and [RFC9814].
   They are not proposed as the initial suite because their signature
   sizes and signing costs are substantially higher than ML-DSA in the
   available measurements.

   FN-DSA (Falcon), MAYO, SNOVA, and HAWK are additional candidates for
   future evaluation.  They are outside this profile until stable PKIX
   and CMS profiles are available and referenced by a future revision or
   separate document.  FN-DSA in particular is discussed further in the
   Algorithm Selection Rationale, because its compact signatures make it
   an attractive candidate for the RPKI's bulk validation model.

   Other Composite ML-DSA combinations specified by LAMPS remain
   candidates for comparison.  Changing the component pair would not
   change the composite plus mixed-tree migration design selected by
   this revision.  A composite signature is a new algorithm from the
   point of view of an RP: a validator that only supports the RSA
   Current Suite cannot validate a composite object.

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6.4.  Classical Reference Points

   To relativize the cost of PQC candidates, this document uses two
   compact classical algorithms as non-normative reference points: ECDSA
   P-256 with SHA-256 [FIPS186-5], which is already used for BGPsec
   UPDATE signatures [RFC8608], and Ed25519 [RFC8032].  Neither is a
   CRQC-resistant algorithm, and neither is proposed here as an RPKI
   suite.  They represent the realistic lower bound for signature and
   key sizes in the non-PQ universe: the deployed RSA-2048 profile is
   itself several times larger than these curves, and PQC candidates
   should be compared against both baselines rather than against RSA
   alone.

6.5.  Algorithm Comparison

   The table below summarizes the static parameters of the candidate and
   reference algorithms, taken from the defining standards.  These
   values are properties of the algorithms themselves and are
   independent of any implementation.

           +=====================+======+============+=========+
           | Algorithm           | Cat. | PubKey (B) | Sig (B) |
           +=====================+======+============+=========+
           | RSA-2048/SHA-256    | n/a  | 270        | 256     |
           +---------------------+------+------------+---------+
           | P-256/SHA-256       | n/a  | 65         | ~72     |
           +---------------------+------+------------+---------+
           | Ed25519             | n/a  | 32         | 64      |
           +---------------------+------+------------+---------+
           | ML-DSA-44           | 2    | 1312       | 2420    |
           +---------------------+------+------------+---------+
           | ML-DSA-65           | 3    | 1952       | 3309    |
           +---------------------+------+------------+---------+
           | ML-DSA-87           | 5    | 2592       | 4627    |
           +---------------------+------+------------+---------+
           | FN-DSA-512 (Falcon) | 1    | 897        | <=666   |
           +---------------------+------+------------+---------+
           | SLH-DSA-SHAKE-128s  | 1    | 32         | 7856    |
           +---------------------+------+------------+---------+
           | SLH-DSA-SHAKE-192s  | 3    | 48         | 16224   |
           +---------------------+------+------------+---------+

                                  Table 1

   "Cat." is the NIST security category; "n/a" marks classical reference
   algorithms.  The RSA-2048 public key size is the DER-encoded SPKI
   payload, the other public key sizes are raw key encodings, and ECDSA
   signature sizes vary slightly with DER encoding.

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   Beyond static sizes, this document evaluates candidates along the
   following dimensions: certificate and CRL size under the RPKI
   profile; CMS signed object size; signing and verification cost under
   the RP workload; repository size and distribution (RRDP and rsync)
   impact; CA key rollover and publication cycle impact; HSM support;
   and standardization and implementation maturity.

   Three qualitative observations from the preliminary evidence inform
   the rationale in the next section.  First, RP workload is
   verification dominated: an RP verifies repository objects but signs
   nothing as part of validation, and the deployed RSA profile is
   exceptionally cheap at verification, so the cost of a lattice
   migration falls disproportionately on RPs rather than on CAs.
   Second, first-order size models place ML-DSA-65 near a fourfold
   repository size increase over the RSA baseline, ML-DSA-44 near
   threefold, and FN-DSA-512 well below twofold.  Third, FN-DSA
   verification is fast, which is directly relevant to the RP workload
   and supports keeping FN-DSA in the comparison set despite the
   maturity concerns discussed below.

   Preliminary measurements supporting these observations, together with
   their conditions, caveats, and the list of dimensions not yet backed
   by confirmed measurements, are collected in Appendix A of this
   revision (to be removed before publication) and are maintained in
   reproducible form by the experimental harness [pqc-rpki-lab].
   Measured values are implementation and environment dependent and are
   not protocol requirements.

6.6.  Algorithm Selection Rationale

   This revision selects a composite suite because a global RPKI
   migration should not depend exclusively on a newly deployed PQC
   algorithm.  The LAMPS construction accepts a composite signature only
   when both component signatures validate.  For a classical adversary,
   existential unforgeability is therefore retained when either ML-
   DSA-65 or ECDSA P-256 remains secure and the prehash construction
   remains collision resistant.  This provides a hedge against a
   cryptanalytic break or an independent implementation defect affecting
   one component during the transition.

   This hedge has a limit.  A CRQC defeats the ECDSA component, so
   security against a quantum adversary still depends on ML-DSA-65
   remaining secure.  The composite suite also does not protect against
   failures shared by both components or by the combiner, encoding, key
   management, or validation implementation.

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   ML-DSA-65 is used as the PQC component of the primary experimental
   suite because it has an existing FIPS signature specification
   [FIPS204] and corresponding PKIX [RFC9881] and CMS [RFC9882]
   algorithm identifier specifications, because implementations are
   becoming widely available, and because Category 3 provides a
   conservative security margin for a suite whose re-migration would be
   a global, multi-year operation.  It is not selected because it is the
   smallest or fastest possible signature algorithm; it is neither.

   The choice between ML-DSA-44 and ML-DSA-65 is genuinely open.  The
   argument for ML-DSA-65 is conservatism: the RPKI is a single global
   system, algorithm migrations in it are slow and expensive, and a
   larger security margin reduces the probability of needing another
   migration.  The argument for ML-DSA-44 is that a structural
   cryptanalytic break of module lattices would likely affect all ML-DSA
   parameter sets, so the extra category mainly protects against gradual
   erosion of concrete security estimates rather than against a
   qualitative break; under that view, the roughly 25-35% smaller keys
   and signatures of ML-DSA-44, or a small-PQ composite built on it, may
   be a better use of the size budget [Doesburg2025].  This document
   keeps ML-DSA-65 as the conservative default for experimentation,
   keeps ML-DSA-44 in the measured comparison, and records the parameter
   set choice as an Open Issue for SIDROPS.

   ML-DSA-87 provides a higher-security comparison point, but its size
   and performance costs make it unattractive as the general repository
   suite.

   FN-DSA (Falcon) is an attractive candidate on size and performance
   grounds: its signatures are roughly one fifth the size of ML-DSA-65
   signatures, and both published RPKI analysis [Doesburg2025] and
   repository-scale redesign work [pqRPKI] identify Falcon as the
   compact lattice option.  This document nevertheless treats FN-DSA as
   an additional candidate for future evaluation rather than a primary
   candidate, for the following reasons:

   *  This document does not profile FN-DSA because it does not
      reference a final FN-DSA standard together with stable PKIX and
      CMS profiles.

   *  FN-DSA signing relies on floating-point Gaussian sampling, which
      is difficult to implement in constant time; side-channel-resistant
      implementations are an active research and engineering concern.
      This is particularly relevant for CA signing keys held in HSMs.

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   *  Availability of FN-DSA in the platforms that RPKI CAs, RIRs, HSM
      vendors, and validator implementations actually use is a separate
      question from the algorithm's intrinsic merits.  No production
      RPKI CA or RP support has been demonstrated.

   These are reasons to sequence the evaluation, not to dismiss the
   algorithm.  FN-DSA remains in the comparison set as the compact
   signature candidate, and the conditions under which it should be
   promoted are recorded as an Open Issue.

   Algorithm selection for the RPKI cannot be based on software
   benchmarks alone.  HSM support for a candidate algorithm is also a
   deployment prerequisite for CAs that protect their signing keys in
   HSMs.

7.  Resource Certificate and CRL Profile

   RPKI resource certificates and CRLs using the primary composite suite
   MUST follow [I-D.ietf-lamps-pq-composite-sigs].  The SPKI
   AlgorithmIdentifier of a subject using the composite suite MUST
   contain id-MLDSA65-ECDSA-P256-SHA512, and its parameters MUST be
   absent.  A certificate or CRL signed by a composite-suite issuer MUST
   use that identifier in its signatureAlgorithm field, with absent
   parameters.  A transition certificate signed by a Current Suite
   issuer instead retains the issuer's Current Suite signatureAlgorithm
   while carrying the composite identifier in the subject SPKI.  Public
   key and signature values MUST use the encodings defined for their
   respective algorithms.

   Resource certificate requests made under [RFC6487] for a composite-
   suite subject MUST carry the same composite SPKI identifier and
   encoding.  A proof-of-possession signature in the request MUST use
   the composite signature identifier and encoding.

   Pure ML-DSA certificates and CRLs used for component measurements
   follow [RFC9881], but pure ML-DSA is not the primary Next Suite
   selected by this revision.

   For RPKI CA certificates, the keyUsage extension MUST remain
   consistent with the resource certificate profile.  A CA certificate
   that is used to issue certificates and CRLs requires keyCertSign and
   cRLSign.  An EE certificate used for an RPKI signed object requires
   digitalSignature and MUST NOT be used as a CA certificate.

   This document does not change the RPKI resource extension semantics,
   certificate policy OID, certificate path validation procedure,
   manifest processing rules, or CRL processing rules.

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8.  CMS Signed Object Profile

   RPKI signed objects using the primary composite suite MUST follow
   [I-D.ietf-lamps-cms-composite-sigs] and the RPKI signed object
   template defined in [RFC6488], as updated by [RFC9589].

   The signatureAlgorithm field of SignerInfo MUST contain id-MLDSA65-
   ECDSA-P256-SHA512.  AlgorithmIdentifier parameters MUST be absent.

   For this composite suite, the digestAlgorithms field of SignedData
   and the digestAlgorithm field of SignerInfo MUST contain id-sha512.
   The parameters field of that AlgorithmIdentifier MUST be absent.  The
   message-digest signed attribute MUST contain the SHA-512 digest of
   the eContent.

   The signedAttrs element remains REQUIRED for RPKI signed objects.  In
   accordance with [RFC6488] as updated by [RFC9589], it MUST contain
   exactly one content-type attribute, one message-digest attribute, and
   one signing-time attribute.  The binary-signing-time attribute and
   all other signed attributes MUST be absent.  The RPKI signed object
   profile restricts signedAttrs to those three attributes.

   The CMS eContentType and eContent for ROAs, manifests, and other RPKI
   signed objects are unchanged.  Validators MUST apply the object-
   specific validation rules after CMS signature validation exactly as
   they do for the Current Suite.

9.  Signed Object Coverage

   Manifests [RFC9286], ROAs [RFC9582], Signed Checklists [RFC9323],
   ASPA objects [I-D.ietf-sidrops-aspa-profile], TAK objects [RFC9691],
   and any future object types built on the RFC 6488 template share one
   CMS structure, one EE certificate model, and one repository.  This
   document applies a single signature algorithm suite uniformly to all
   of them.  Migrating, for example, ROAs to a PQC suite while leaving
   ASPA objects on RSA would create little benefit and considerable
   complexity: the objects are protected by the same certification
   chain, distributed through the same repository, and broken by the
   same CRQC.

   Changing the signature algorithm does not change an object's
   eContentType, payload, or object-specific validation rules.  A future
   standards-track profile that selects a new mandatory RPKI algorithm
   suite would update [RFC7935].  An object-specific RFC needs an update
   only if that object's payload or validation semantics also change;
   this document makes no such change.

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   BGPsec UPDATE signatures are not RFC 6488 signed objects and are not
   covered by this profile.  BGPsec Router Certificates and their
   covering CRLs and manifests are repository products and are covered,
   as described in the Scope section.

10.  Manifests and Repository Processing

10.1.  Manifest Scope During Migration

   A manifest covers the products of one CA instance at one publication
   point, as specified by [RFC9286].  The manifest is signed with a one-
   time-use EE certificate issued by that CA.  Its fileList contains the
   certificates issued and published by that CA, the CA's current CRL,
   and signed objects whose embedded EE certificates were issued by that
   CA.

   The relevant RP check is therefore issuer and publication-scope
   consistency, not equality between the manifest signing key and
   product keys.  An RP validates the manifest EE certificate under the
   associated CA, verifies each listed certificate, CRL, or signed
   object under that same CA instance as required by its object profile,
   and checks the publication point, file name, and file hash according
   to [RFC9286].  A shared publication point can contain products from
   multiple CA instances during key rollover, but each manifest covers
   only its associated CA instance.

   Mixed Certification Chains and composite signatures do not change
   these checks.  This document therefore introduces no additional
   requirement for the manifest EE key to equal a key used by a listed
   product, and it does not weaken the existing RP checks that bind
   every listed product to the manifest's CA scope.

10.2.  Parallel Publication Mechanics

   This document does not define new payload encodings for manifests,
   ROAs, or CRLs.  Repository operators MAY publish Current Suite and
   Next Suite products in parallel during an algorithm transition.  A
   repository that publishes parallel products MUST ensure that
   manifests and CRLs are internally consistent within each suite.

   During parallel publication, operators SHOULD provide a way to
   identify corresponding products across suites for measurement and
   debugging.  This identification MAY be derived from publication point
   structure, object names, CA hierarchy, or an implementation-specific
   mapping.  It is not a new on-wire RPKI object in this version.

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11.  Relying Party Behavior

   An RP that implements this document MUST be configurable with an
   accepted algorithm policy covering certificate SPKI algorithms and
   signature algorithms.  The policy MUST be able to represent at least:

   *  Current Suite only;

   *  Current Suite plus Next Suite;

   *  Next Suite preferred with Current Suite fallback;

   *  Next Suite only.

   An RP MUST reject a certificate whose SPKI algorithm or signature
   algorithm is not in its configured policy.  It MUST likewise reject a
   CRL or signed object whose signature algorithm is not in that policy.
   The rejection reason SHOULD be reported distinctly from syntax
   errors, path validation failures, manifest failures, and object-
   specific semantic failures.

   An RP that processes Mixed Certification Chains MUST process each
   certificate or CRL signatureAlgorithm independently and verify the
   signature with the issuer's public key.  It MUST NOT infer the
   subject SPKI algorithm from the certificate signatureAlgorithm or
   require those two fields to identify the same algorithm.

   An RP that validates both Current Suite and Next Suite products
   SHOULD perform semantic-equivalence checks for corresponding
   products.  For ROAs, this check compares the resulting VRP set by
   prefix, maxLength, origin AS, and trust anchor context.  The
   Canonical Cache Representation [I-D.ietf-sidrops-rpki-ccr] provides a
   suitable mechanism: if the ROAPayloadState hashes of two validation
   runs match, the VRP sets consumed by routers are identical, and if
   they differ, the decoded payload states identify the divergent VRPs.
   If the Current Suite and Next Suite produce different routing
   semantics, the RP SHOULD emit telemetry and SHOULD NOT silently merge
   the divergent outputs.

   This document does not require routers to support PQC.  Routers
   receive validated payloads through RTR or local export formats, and
   the semantic content of that output is intended to be unchanged by
   the algorithm migration.

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12.  Migration Considerations

   The intended migration combines a composite signature suite with a
   Mixed Certification Chain.  A parent CA using the Current Suite
   issues a child CA certificate whose SPKI contains the composite-suite
   public key.  The child CA then issues certificates and CRLs and signs
   CMS objects with the composite suite.  This moves one subtree at a
   time without creating parallel production objects with potentially
   different payloads.

   Before a production subtree is switched, the composite profile and
   the mixed-chain path must be supported by the issuing CA and by the
   RP population.  The transition therefore proceeds through
   implementation, test repositories under test TALs, RP readiness
   measurement, staged subtree migration, and eventual retirement of the
   Current Suite.

12.1.  Parallel Publication and Semantic Divergence

   Parallel Publication is useful in test repositories for comparing a
   Current Suite branch with a candidate branch.  It is not the
   preferred production transition because independent branches can
   diverge through publication failures, timing skew, software defects,
   or configuration drift.  Experiments using parallel branches MUST
   compare their resulting VRP sets.  CCR [I-D.ietf-sidrops-rpki-ccr]
   may be used as the common representation for that comparison.

12.2.  Composite Signatures

   Composite signatures [I-D.ietf-lamps-pq-composite-sigs]
   [I-D.ietf-lamps-cms-composite-sigs] bind a classical and a PQC
   signature to one object and one payload.  This avoids cross-branch
   semantic divergence and permits the classical component to protect
   the object if the PQC component is found to have a security defect
   while the classical component remains secure.  Conversely, ML-DSA-65
   protects against a CRQC when ECDSA P-256 no longer does.  This hedge
   is a primary reason for selecting a composite suite rather than a
   pure PQC suite in this revision.

   The LAMPS verification rule requires every component signature to
   validate.  An implementation MUST NOT accept the composite signature
   when either component fails.  A composite suite is nevertheless a new
   algorithm to every RP and combines the size and processing cost of
   its components.  Its use therefore depends on stable PKIX and CMS
   profiles and interoperable CA and RP implementations.

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12.3.  Mixed Certification Chains and Mixed-Tree Migration

   The parent signs the transition certificate using the algorithm
   associated with the parent's key, while the child SPKI carries the
   composite-suite key.  Below that boundary, the child uses the
   composite suite for its CA certificates, CRLs, and CMS signed
   objects.  The two algorithm fields are independent; an RP MUST
   process each certificate or CRL signatureAlgorithm and verify the
   signature with the issuer's public key.

   This pattern requires no new RPKI object format.  It does require RPs
   to support both the transition certificate and the suite used below
   it.  A subtree switched before RP support is sufficiently deployed is
   rejected by legacy RPs, so RP readiness is a precondition for each
   production switch.  CA implementations and HSMs must also support the
   selected suite, and repository size, transfer, and validation costs
   must be measured before deployment.

13.  Implementation Status

   This section records the status of known implementations of the
   protocol defined by this specification at the time of posting of this
   Internet-Draft, and is based on a proposal described in [RFC7942].
   It is intended to assist IETF discussion and is to be removed before
   publication as an RFC.

   An experimental repository, pqc-rpki-lab, was used to evaluate this
   proposal.  The evaluation is at an early stage; the lists below
   distinguish what has actually run from what has not.

   Implemented:

   *  Static algorithm metadata for the algorithms in the comparison
      table.

   *  Primitive benchmarks using existing libraries, unified under a
      single OpenSSL CLI code path with comparable-group metadata and an
      automated results-validation guard.

   *  A recorded bulk measurement of 100,000 signing and 100,000
      verification operations for RSA-2048, P-256, Ed25519, ML-DSA-
      44/65/87, and FN-DSA-512, plus sequential component measurements
      for ten two-algorithm combinations, with conditions documented
      alongside the results (see Appendix A).

   *  Synthetic repository impact estimator.

   *  Local cache size collector.

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   *  VRP semantic equivalence checker for CSV/JSON fixtures; on the
      current fixtures, the classical-side and PQC-side normalized VRP
      hashes match.  Its interim hash is computed over canonical JSON
      and is not a CCR hash; results from it are not labeled as CCR
      output.

   *  Mixed-tree test structure generation (RSA trust anchor, ML-DSA-65
      child CA SPKI, child products keyed consistently); structural
      consistency checks pass.

   *  Certificate and CRL generation with OpenSSL 3.6.2 for RSA-2048,
      P-256, Ed25519, ML-DSA-44/65/87, FN-DSA-512, SLH-DSA-SHAKE-128s,
      and SLH-DSA-SHAKE-192s, using the applicable PKIX profiles where
      standardized.

   *  RFC 6488 ML-DSA-65 CMS SignedData generation through the OpenSSL
      CMS API with explicit SHA-512, independently cross-checked by a
      minimal DER assembler, including complete ROA and manifest
      fixtures.

   *  Repeated 32-byte, 512-byte, 2-KiB, and 8-KiB primitive
      measurements, with 1000 operations in each of 10 repetitions, key-
      generation timing, variance, and process peak-RSS observations.

   *  Isolated local-rsync validation with pinned unmodified Routinator,
      rpki-client, and FORT containers.  All accepted the RSA baseline
      and rejected the ML-DSA-65 trust anchor or certificate before
      processing its complete repository.

   Not yet implemented or incomplete:

   *  Complete ML-DSA-44, ML-DSA-87, and SLH-DSA CMS signed-object
      fixtures.

   *  Acceptance by a validator extended for this profile and
      corresponding Routinator or other validator patch evaluation.

   *  Krill integration for production-like CA issuance, manifest and
      ROA signing, and publication.

   *  A complete mixed-tree repository accepted by an extended RP; the
      current mixed-tree fixture is structural.

   *  RRDP and rsync impact measurement with real object corpora.

   *  CCR-based semantic equivalence testing across suites, using real
      RP output rather than fixtures.

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   *  FN-DSA measurement through the same OpenSSL EVP path used for the
      other algorithms (current FN-DSA numbers come from liboqs
      components).

   *  Measurement of actual composite encodings per the LAMPS composite
      specifications (current composite numbers are sequential component
      lower bounds).

   *  HSM performance and support investigation.

   The highest-priority implementation gap is generation and validation
   of the selected Composite ML-DSA objects, followed by acceptance by
   an RP extended for the profile and production-like CA support in
   Krill or equivalent software.  The complete pure ML-DSA-65 objects
   and unmodified-validator rejection baseline provide component-level
   inputs for that work, but do not establish composite
   interoperability.

14.  Security Considerations

   This document addresses forgery of RPKI signatures in the presence of
   a CRQC.  Existing considerations for CA compromise, repository
   compromise, operational misissuance, BGP policy mistakes, and route
   leaks are unchanged.

   Downgrade and inconsistent suite selection are primary concerns
   during a long transition.  An RP that supports both Current Suite and
   Next Suite products MUST make its algorithm acceptance policy
   explicit.  It MUST NOT silently accept a Current Suite product as
   equivalent to a missing or invalid Next Suite product when local
   policy requires the Next Suite.  Divergent suite-selection policies
   across the RP population can cause different RPs to derive different
   VRP sets from the same repository; this is a systemic risk of the
   transition period itself, and it persists for as long as classical
   and PQC suites coexist.

   Parallel publication introduces the possibility of semantic
   divergence.  For example, the RSA branch and the PQC branch might
   contain different ROA payloads, stale manifests, or different CRL
   state.  Validators SHOULD detect and report these cases rather than
   silently selecting one branch without operator visibility; see the
   Migration Considerations section.

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   Mixed Certification Chains introduce the risk of confusing the
   Certificate Signature Algorithm with the Subject Public Key
   Algorithm.  An implementation that assumes the two are equal may
   accept invalid chains or reject valid ones.  Implementations MUST
   process each certificate or CRL signatureAlgorithm independently,
   verify the signature with the issuer's public key, and process the
   subject SPKI algorithm as a separate field.

   Validators that do not support a Next Suite face a fail-open versus
   fail-closed choice: treating unsupported-algorithm objects as absent
   (potentially discarding protections the CA intended to publish) or
   treating them as errors (potentially discarding an entire publication
   point).  Neither behavior is safe in all situations; what matters is
   that the behavior is explicit, configurable, and observable,
   consistent with the "unknown algorithm" handling direction of RFC
   6916.  How mixed deployments with unsupported validators should be
   handled at internet scale remains an Open Issue.

   Larger public keys, signatures, certificates, CRLs, and CMS objects
   enlarge the repository fetch and validation attack surface.  A
   hostile or misbehaving publication point can impose disproportionate
   transfer and CPU cost on RPs, and PQC object sizes raise the ceiling
   of that cost.  Implementations SHOULD enforce resource limits and
   telemetry for object size, number of objects, validation time, and
   memory use.  Operators SHOULD evaluate RRDP snapshot and delta sizes
   before large-scale deployment.

   HSM implementations of PQC algorithms are newer than their software
   counterparts and may lag in side-channel hardening, fault-attack
   resistance, and certification.  A CA key that is protected against
   extraction but signs with a leaky implementation is not protected.
   Side-channel risk is algorithm dependent: FN-DSA's floating-point
   Gaussian sampling is a known hard case for constant-time
   implementation, which is one reason this document sequences FN-DSA
   after ML-DSA.

   ML-DSA uses randomized (hedged) signing by default.  CA
   implementations and HSMs MUST use cryptographically appropriate
   randomness and SHOULD follow the operational guidance in RFC 9881 and
   RFC 9882.  Randomness failures during signing weaken the hedge
   against side-channel and fault attacks; purely deterministic signing
   is not preferred on platforms where such attacks are a concern.

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   Algorithm confusion is possible if AlgorithmIdentifier parameters,
   SignerInfo digestAlgorithm, CMS signed attributes, or certificate
   SubjectPublicKeyInfo encodings are inconsistently handled.
   Implementations MUST reject malformed AlgorithmIdentifier encodings
   and MUST follow the parameter rules of the referenced LAMPS
   specifications.

   Composite signatures may protect against failures in one component
   algorithm only when every component is verified and the other
   component and the prehash construction remain secure.  Component keys
   MUST NOT be reused as standalone keys or in other composite
   combinations, as required by [I-D.ietf-lamps-pq-composite-sigs].
   Reuse can enable stripping and cross-protocol attacks.  A shared
   implementation defect, a combiner or parser defect, or compromise of
   both component keys is not mitigated by the composite construction.
   After a CRQC breaks ECDSA, the composite suite's unforgeability
   depends on ML-DSA-65.

15.  IANA Considerations

   This document requests no IANA actions.  It reuses algorithm
   identifiers defined by the referenced LAMPS specifications and
   defines no new RPKI object type, file extension, or content type.

16.  Open Issues

   The following issues require additional SIDROPS discussion and
   implementation evidence.  In particular, this draft should not
   promote the experimental composite suite to a production requirement
   until extended validator behavior is measured.

16.1.  Algorithm Selection

   *  Whether the final standards-track profile should retain the ML-
      DSA-65 and ECDSA P-256 component pair selected for this
      experiment, or use another LAMPS Composite ML-DSA combination.

   *  Under what conditions FN-DSA should be promoted from a future
      evaluation candidate: completion of the FN-DSA standard, stable
      PKIX/CMS conventions, evidence of side-channel-resistant
      implementations, and HSM availability.

16.2.  Migration Design

   *  Whether composite signatures combined with mixed-tree migration
      are the appropriate production transition design, based on
      implementation, interoperability, repository impact, and RP-
      readiness evidence.

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   *  How RP-side readiness should be measured before any production CA
      switches suites under a mixed-tree migration, given that a
      switched subtree is invisible to non-upgraded RPs.

   *  How to handle validators that do not support the Next Suite in
      mixed deployments (fail-open versus fail-closed, and reporting).

   *  How to define a transition timetable and readiness metrics, and
      whether that work should update or replace RFC 6916.

   *  How provisioning and publication software will roll the BPKI trust
      anchors and EE certificates used for existing relationships,
      including relationships established through [RFC8183], before
      those protocols depend on a PQC algorithm.  The procedure needs
      overlap, rollback, and recovery behavior and can be prepared
      independently of the final RPKI object-signature algorithm choice.

16.3.  Operational Readiness

   *  Which PQC signature algorithms RIR CA teams and their HSM vendors
      plan to support, on what firmware, API, certification, and
      deployment timelines.

   *  Whether claimed HSM support uses a general-purpose CPU
      implementation within the HSM boundary or native hardware or FPGA
      acceleration, and how those implementation choices affect key
      generation, signing latency, throughput, side-channel properties,
      and operational capacity.

17.  Normative References

   [BCP14]    Best Current Practice 14,
              <https://www.rfc-editor.org/info/bcp14>.
              At the time of writing, this BCP comprises the following:

              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>.

              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>.

   [RFC6480]  Lepinski, M. and S. Kent, "An Infrastructure to Support
              Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
              February 2012, <https://www.rfc-editor.org/info/rfc6480>.

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   [RFC6487]  Huston, G., Michaelson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates", RFC 6487,
              DOI 10.17487/RFC6487, February 2012,
              <https://www.rfc-editor.org/info/rfc6487>.

   [RFC6488]  Lepinski, M., Chi, A., and S. Kent, "Signed Object
              Template for the Resource Public Key Infrastructure
              (RPKI)", RFC 6488, DOI 10.17487/RFC6488, February 2012,
              <https://www.rfc-editor.org/info/rfc6488>.

   [RFC6916]  Gagliano, R., Kent, S., and S. Turner, "Algorithm Agility
              Procedure for the Resource Public Key Infrastructure
              (RPKI)", BCP 182, RFC 6916, DOI 10.17487/RFC6916, April
              2013, <https://www.rfc-editor.org/info/rfc6916>.

   [RFC7935]  Huston, G. and G. Michaelson, Ed., "The Profile for
              Algorithms and Key Sizes for Use in the Resource Public
              Key Infrastructure", RFC 7935, DOI 10.17487/RFC7935,
              August 2016, <https://www.rfc-editor.org/info/rfc7935>.

   [RFC8182]  Bruijnzeels, T., Muravskiy, O., Weber, B., and R. Austein,
              "The RPKI Repository Delta Protocol (RRDP)", RFC 8182,
              DOI 10.17487/RFC8182, July 2017,
              <https://www.rfc-editor.org/info/rfc8182>.

   [RFC8209]  Reynolds, M., Turner, S., and S. Kent, "A Profile for
              BGPsec Router Certificates, Certificate Revocation Lists,
              and Certification Requests", RFC 8209,
              DOI 10.17487/RFC8209, September 2017,
              <https://www.rfc-editor.org/info/rfc8209>.

   [RFC9286]  Austein, R., Huston, G., Kent, S., and M. Lepinski,
              "Manifests for the Resource Public Key Infrastructure
              (RPKI)", RFC 9286, DOI 10.17487/RFC9286, June 2022,
              <https://www.rfc-editor.org/info/rfc9286>.

   [RFC9582]  Snijders, J., Maddison, B., Lepinski, M., Kong, D., and S.
              Kent, "A Profile for Route Origin Authorizations (ROAs)",
              RFC 9582, DOI 10.17487/RFC9582, May 2024,
              <https://www.rfc-editor.org/info/rfc9582>.

   [RFC9589]  Snijders, J. and T. Harrison, "On the Use of the
              Cryptographic Message Syntax (CMS) Signing-Time Attribute
              in Resource Public Key Infrastructure (RPKI) Signed
              Objects", RFC 9589, DOI 10.17487/RFC9589, May 2024,
              <https://www.rfc-editor.org/info/rfc9589>.

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   [RFC9691]  Martinez, C., Michaelson, G., Harrison, T., Bruijnzeels,
              T., and R. Austein, "A Profile for Resource Public Key
              Infrastructure (RPKI) Trust Anchor Keys (TAKs)", RFC 9691,
              DOI 10.17487/RFC9691, December 2024,
              <https://www.rfc-editor.org/info/rfc9691>.

   [RFC9881]  Massimo, J., Kampanakis, P., Turner, S., and B. E.
              Westerbaan, "Internet X.509 Public Key Infrastructure --
              Algorithm Identifiers for the Module-Lattice-Based Digital
              Signature Algorithm (ML-DSA)", RFC 9881,
              DOI 10.17487/RFC9881, October 2025,
              <https://www.rfc-editor.org/info/rfc9881>.

   [RFC9882]  Salter, B., Raine, A., and D. Van Geest, "Use of the ML-
              DSA Signature Algorithm in the Cryptographic Message
              Syntax (CMS)", RFC 9882, DOI 10.17487/RFC9882, October
              2025, <https://www.rfc-editor.org/info/rfc9882>.

   [I-D.ietf-lamps-pq-composite-sigs]
              Ounsworth, M., Gray, J., Pala, M., Klaussner, J., and S.
              Fluhrer, "Composite Module-Lattice-Based Digital Signature
              Algorithm (ML-DSA) for use in X.509 Public Key
              Infrastructure", Work in Progress, Internet-Draft, draft-
              ietf-lamps-pq-composite-sigs-19, 21 April 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-lamps-
              pq-composite-sigs-19>.

   [I-D.ietf-lamps-cms-composite-sigs]
              Ounsworth, M., Gray, J., Klaussner, J., and D. Van Geest,
              "Composite Module-Lattice-Based Digital Signature
              Algorithm (ML-DSA) for use in Cryptographic Message Syntax
              (CMS)", Work in Progress, Internet-Draft, draft-ietf-
              lamps-cms-composite-sigs-05, 22 May 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-lamps-
              cms-composite-sigs-05>.

   [FIPS204]  National Institute of Standards and Technology, "Module-
              Lattice-Based Digital Signature Standard", FIPS 204,
              August 2024, <https://doi.org/10.6028/NIST.FIPS.204>.

18.  Informative References

   [RFC7942]  Sheffer, Y. and A. Farrel, "Improving Awareness of Running
              Code: The Implementation Status Section", BCP 205,
              RFC 7942, DOI 10.17487/RFC7942, July 2016,
              <https://www.rfc-editor.org/info/rfc7942>.

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   [RFC8032]  Josefsson, S. and I. Liusvaara, "Edwards-Curve Digital
              Signature Algorithm (EdDSA)", RFC 8032,
              DOI 10.17487/RFC8032, January 2017,
              <https://www.rfc-editor.org/info/rfc8032>.

   [RFC8183]  Austein, R., "An Out-of-Band Setup Protocol for Resource
              Public Key Infrastructure (RPKI) Production Services",
              RFC 8183, DOI 10.17487/RFC8183, July 2017,
              <https://www.rfc-editor.org/info/rfc8183>.

   [RFC8608]  Turner, S. and O. Borchert, "BGPsec Algorithms, Key
              Formats, and Signature Formats", RFC 8608,
              DOI 10.17487/RFC8608, June 2019,
              <https://www.rfc-editor.org/info/rfc8608>.

   [RFC9323]  Snijders, J., Harrison, T., and B. Maddison, "A Profile
              for RPKI Signed Checklists (RSCs)", RFC 9323,
              DOI 10.17487/RFC9323, November 2022,
              <https://www.rfc-editor.org/info/rfc9323>.

   [RFC9814]  Housley, R., Fluhrer, S., Kampanakis, P., and B.
              Westerbaan, "Use of the SLH-DSA Signature Algorithm in the
              Cryptographic Message Syntax (CMS)", RFC 9814,
              DOI 10.17487/RFC9814, July 2025,
              <https://www.rfc-editor.org/info/rfc9814>.

   [RFC9909]  Bashiri, K., Fluhrer, S., Gazdag, S., Van Geest, D., and
              S. Kousidis, "Internet X.509 Public Key Infrastructure --
              Algorithm Identifiers for the Stateless Hash-Based Digital
              Signature Algorithm (SLH-DSA)", RFC 9909,
              DOI 10.17487/RFC9909, December 2025,
              <https://www.rfc-editor.org/info/rfc9909>.

   [I-D.ietf-sidrops-rpki-ccr]
              Snijders, J., Bakker, B., Bruijnzeels, T., and T. Buehler,
              "A Profile for Resource Public Key Infrastructure (RPKI)
              Canonical Cache Representation (CCR)", Work in Progress,
              Internet-Draft, draft-ietf-sidrops-rpki-ccr-11, 1 July
              2026, <https://datatracker.ietf.org/doc/html/draft-ietf-
              sidrops-rpki-ccr-11>.

   [I-D.ietf-sidrops-aspa-profile]
              Snijders, J., Azimov, A., Uskov, E., Bush, R., Housley,
              R., and B. Maddison, "A Profile for Autonomous System
              Provider Authorization", Work in Progress, Internet-Draft,
              draft-ietf-sidrops-aspa-profile-27, 19 June 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-sidrops-
              aspa-profile-27>.

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   [FIPS186-5]
              National Institute of Standards and Technology, "Digital
              Signature Standard (DSS)", FIPS 186-5, February 2023,
              <https://doi.org/10.6028/NIST.FIPS.186-5>.

   [FIPS205]  National Institute of Standards and Technology, "Stateless
              Hash-Based Digital Signature Standard", FIPS 205, August
              2024, <https://doi.org/10.6028/NIST.FIPS.205>.

   [Doesburg2025]
              Doesburg, D., "Post-Quantum Cryptography for the RPKI",
              June 2025, <https://www.sidnlabs.nl/en/news-and-blogs/
              thesis-pqc-for-the-rpki>.

   [pqRPKI]   al., W. L. E., "pqRPKI: A Practical RPKI Architecture for
              the Post-Quantum Era", March 2026,
              <https://arxiv.org/abs/2603.06968>.

   [pqc-rpki-lab]
              Yoshikawa, T., "pqc-rpki-lab experimental harness", July
              2026, <https://github.com/marokiki/pqc-rpki-
              lab/releases/tag/draft-yoshikawa-sidrops-pqc-rpki-01>.

Appendix A.  Preliminary Measurement Results

   This appendix records preliminary measurements referenced by the
   Algorithm Comparison and Implementation Status sections.  All values
   were produced by the experimental harness [pqc-rpki-lab], which
   contains the corresponding scripts, raw outputs, and environment
   metadata.  This appendix is to be removed before publication as an
   RFC; the harness remains the durable record.

A.1.  Measured Certificate and CRL Sizes

   RFC 6487-profiled certificates (including RFC 3779 resource
   extensions) and CRLs generated with the OpenSSL 3.6.2 default
   provider:

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     +=========================+=============+=============+=========+
     | Algorithm               | CA cert (B) | EE cert (B) | CRL (B) |
     +=========================+=============+=============+=========+
     | RSA-2048/SHA-256        | 1038        | 984         | 381     |
     +-------------------------+-------------+-------------+---------+
     | P-256/SHA-256           | 641         | 587         | 187     |
     +-------------------------+-------------+-------------+---------+
     | Ed25519                 | 578         | 524         | 170     |
     +-------------------------+-------------+-------------+---------+
     | ML-DSA-44               | 4238        | 4184        | 2541    |
     +-------------------------+-------------+-------------+---------+
     | ML-DSA-65               | 5767        | 5713        | 3430    |
     +-------------------------+-------------+-------------+---------+
     | ML-DSA-87               | 7725        | 7671        | 4748    |
     +-------------------------+-------------+-------------+---------+
     | SLH-DSA-SHAKE-128s      | 8390        | 8336        | 7977    |
     +-------------------------+-------------+-------------+---------+
     | SLH-DSA-SHAKE-192s      | 16774       | 16720       | 16345   |
     +-------------------------+-------------+-------------+---------+
     | FN-DSA-512 (Falcon-512) | 2048        | 1991        | 764     |
     +-------------------------+-------------+-------------+---------+

                                  Table 2

   The P-256 and Ed25519 rows use the same RFC 6487 structure and
   resource extensions as the other rows, but are classical comparison
   algorithms rather than RFC 7935 suites.  The FN-DSA-512 row uses the
   experimental Falcon-512 OID and encoding from oqs-provider 0.11.0-rc1
   with liboqs 0.15.0; it is a measured experimental encoding, not a
   final FN-DSA PKIX profile.  Falcon signatures are variable length, so
   its certificate and CRL sizes can vary between runs.

A.2.  Synthetic Repository Size Model

   First-order repository size ratios relative to the RSA-2048 baseline,
   computed by applying static public key and signature sizes to a size
   model of the current global repository.  These are model outputs, not
   full-repository measurements:

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                 +====================+==================+
                 | Algorithm          | Repository ratio |
                 +====================+==================+
                 | Ed25519            | 0.76             |
                 +--------------------+------------------+
                 | P-256              | 0.78             |
                 +--------------------+------------------+
                 | RSA-2048           | 1.00             |
                 +--------------------+------------------+
                 | FN-DSA-512         | 1.55             |
                 +--------------------+------------------+
                 | ML-DSA-44          | 3.08             |
                 +--------------------+------------------+
                 | ML-DSA-65          | 4.01             |
                 +--------------------+------------------+
                 | ML-DSA-87          | 5.28             |
                 +--------------------+------------------+
                 | SLH-DSA-SHAKE-128s | 6.85             |
                 +--------------------+------------------+
                 | SLH-DSA-SHAKE-192s | 13.38            |
                 +--------------------+------------------+

                                  Table 3

A.3.  Bulk Signing and Verification

   Wall-clock seconds for 100,000 signing operations and 100,000
   verification operations:

   +=================================+===============+=================+
   | Algorithm                       | Sign (s/100k) | Verify (s/100k) |
   +=================================+===============+=================+
   | RSA-2048/SHA-256                | 34.3          | 1.0             |
   +---------------------------------+---------------+-----------------+
   | P-256/SHA-256                   | 1.3           | 3.5             |
   +---------------------------------+---------------+-----------------+
   | Ed25519                         | 1.7           | 4.0             |
   +---------------------------------+---------------+-----------------+
   | ML-DSA-44                       | 25.1          | 5.0             |
   +---------------------------------+---------------+-----------------+
   | ML-DSA-65                       | 40.5          | 7.7             |
   +---------------------------------+---------------+-----------------+
   | ML-DSA-87                       | 47.9          | 11.7            |
   +---------------------------------+---------------+-----------------+
   | FN-DSA-512                      | 10.5          | 1.6             |
   +---------------------------------+---------------+-----------------+
   | RSA-2048 + P-256 (components)   | 35.3          | 4.5             |
   +---------------------------------+---------------+-----------------+

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   | RSA-2048 + Ed25519              | 35.6          | 5.1             |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+
   | RSA-2048 + ML-DSA-44            | 59.2          | 5.8             |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+
   | RSA-2048 + ML-DSA-65            | 74.4          | 8.4             |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+
   | RSA-2048 + ML-DSA-87            | 81.1          | 12.7            |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+
   | RSA-2048 + FN-DSA-512           | 44.6          | 2.6             |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+
   | P-256 + ML-DSA-44               | 26.3          | 8.4             |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+
   | P-256 + ML-DSA-65               | 41.8          | 10.9            |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+
   | P-256 + ML-DSA-87               | 50.0          | 15.3            |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+
   | P-256 + FN-DSA-512              | 12.1          | 5.1             |
   | (components)                    |               |                 |
   +---------------------------------+---------------+-----------------+

                                  Table 4

   Conditions: Apple M4, single thread, OpenSSL 3.6.2 invoked through an
   EVP C loop, 32-byte fixed message, 100,000 iterations per data point,
   one recorded run, excluding key generation, I/O, and CMS/X.509
   construction.  Component-combination rows execute both operations
   sequentially in one process; they are lower bounds and include no
   composite encoding or CMS/X.509 overhead.  FN-DSA-512 was measured
   through liboqs 0.15.0 rather than the OpenSSL EVP path, so its rows
   carry an additional comparability caveat.  A single-host, single-run
   measurement does not establish a general performance ordering.

A.4.  Open Measurement Tasks

   The following dimensions are not yet backed by confirmed measurements
   and are deliberately recorded as open tasks rather than numbers:

   *  CA key rollover, publication cycle, and full-repository validation
      impact; RRDP snapshot/delta and rsync transfer impact.

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   *  Full-validator memory footprint.  The repeated primitive sweep
      records process peak RSS, but this is not a repository-validation
      measurement.

   *  HSM performance and support.

Appendix B.  Changes from -00

   This section is to be removed before publication as an RFC.

   *  Changed the primary experimental Next Suite from pure ML-DSA-65 to
      the composite id-MLDSA65-ECDSA-P256-SHA512 signature suite.

   *  Added comparison material for ML-DSA-44, ML-DSA-87, ECDSA P-256,
      Ed25519, FN-DSA/Falcon, and SLH-DSA, including preliminary size
      and performance measurements.

   *  Reworked the migration strategy from a primarily parallel-
      publication model to a mixed-tree migration model toward a
      composite signature suite.

   *  Clarified that BGPsec Router Certificates are in scope, while
      BGPsec UPDATE signatures are out of scope.

   *  Unified the treatment of RPKI signed objects covered by RFC 6488,
      including manifests, ROAs, ASPA objects, RSCs, and TAK objects.

   *  Added terminology for Certificate Signature Algorithm, Subject
      Public Key Algorithm, and Mixed Certification Chain.

   *  Expanded the security considerations for composite signatures,
      mixed-chain validation, downgrade behavior, unsupported
      validators, resource consumption, and implementation risks.

   *  Added Implementation Status and Appendix A with preliminary
      implementation and measurement results.

   *  Clarified that this document requests no IANA actions.

   *  Updated Open Issues to focus on unresolved algorithm-selection,
      migration-design, and operational-readiness questions.

Acknowledgements

   The author thanks Job Snijders, Dirk Doesburg, Loganaden Velvindron,
   and Ties de Kock for their reviews and comments.  The author also
   thanks the SIDROPS and LAMPS communities for the specifications and
   implementation work that make this experiment possible.

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Author's Address

   Tomoki Yoshikawa
   Graduate School of Informatics, Kyoto University
   Email: yoshikawa.tomoki.67i@st.kyoto-u.ac.jp

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