Internet-Draft cose-sqisign September 2026
Mott Expires 8 March 2027 [Page]
Workgroup:
COSE
Internet-Draft:
draft-mott-cose-sqisign-07
Published:
Intended Status:
Standards Track
Expires:
Author:
A. R. Mott
RustyKey®

CBOR Object Signing and Encryption (COSE) and JSON Object Signing and Encryption (JOSE) Registrations for SQIsign

Abstract

NOTE: This document describes a signature scheme based on the SQIsign algorithm currently under evaluation in the 3rd round NIST Post-Quantum Cryptography standardization process. Be aware that the underlying primitive may change as a result of that process.

This document specifies the algorithm encodings and representations for the SQIsign digital signature scheme within the CBOR Object Signing and Encryption (COSE) and JSON Object Signing and Encryption (JOSE) frameworks.

SQIsign is an isogeny-based post-quantum signature scheme that provides an unusually compact signature and public key size among candidates of the NIST Post-Quantum Cryptography (PQC) standardization and on-ramp-to-standardization processes.

The standardization of SQIsign will be helpful to address current infrastructure bottlenecks, specifically the FIDO2 CTAP2 specification used by many in-service devices.

This document clarifies that SQIsign does not expose the auxiliary torsion-point information exploited in the SIDH/SIKE attacks. Consequently, the specific attack techniques of Castryck–Decru do not directly apply. However, the scheme remains subject to ongoing cryptanalysis of isogeny-based constructions. By establishing stable COSE and JOSE identifiers, this document ensures the interoperability required for the seamless integration of post-quantum security into high-density, bandwidth-constrained, and legacy-compatible hardware environments.

About This Document

This note is to be removed before publishing as an RFC.

Status information for this document may be found at https://datatracker.ietf.org/doc/draft-mott-cose-sqisign/.

Discussion of this document takes place on the COSE Working Group mailing list (mailto:cose@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/cose/. Subscribe at https://www.ietf.org/mailman/listinfo/cose/.

Source for this draft and an issue tracker can be found at https://github.com/https://github.com/antonymott/quantum-resistant-rustykey.

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 8 March 2027.

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Table of Contents

1. Introduction

This document registers algorithm identifiers and key type parameters for SQIsign in COSE and JOSE.

1.1. Background and Motivation

Post-quantum cryptography readiness is critical for constrained devices. As of late 2026, while FIDO2/WebAuthn supports various COSE algorithms, some hardware authenticators and platform authenticators (like TPMs) have strict memory/storage constraints, effectively limiting public keys to 1024 bytes or less, hindering the adoption of large-key post-quantum algorithms.

1.1.1. Pressing Need: Smaller PQC Signatures

FN-DSA (Falcon) and ML-DSA (Dilithium) have larger signatures that may not fit in constrained environments. Depending on authenticator implementation, transport (USB/NFC/BLE), and fragmentation support, many CTAP2 authenticators impose practical limits near 1024 bytes for external key communication — well below CTAP2's own protocol ceiling for message reassembly, commonly cited around 7609 bytes [CTAP2-spec]. Post-quantum signature schemes with larger keys or signatures risk pushing messages toward either limit, stressing constrained authenticators and transports. SQIsign-L1, L3, and L5 signatures remain small enough to fit comfortably within both constraints, and are well suited to highly constrained networks such as 802.15.4.

The fundamental differences between ML-DSA, FN-DSA, and SQIsign lie in their underlying hard mathematical problems, implementation complexity, and performance trade-offs.

Falcon (NIST secondary) uses NTRU lattices to achieve very small signatures and fast verification, but requires complex floating-point math. Dilithium (NIST primary) is a balanced, high-efficiency lattice scheme using Module-LWE/SIS, easy to implement.

SQIsign [SQIsign-Spec] [SQIsign-Analysis] is a non-lattice, isogeny-based scheme that offers an unusually small signature compared to other PQC signature candidate under NIST evaluation, historically at the cost of the most computationally intensive signing operation of the group. SQIsign is an isogeny-based digital signature scheme participating in NIST's Round 3 [NIST-3rd-round-candidates] Additional Digital Signature Schemes, not yet a NIST standard.

Early reference implementations, evaluated prior to browser WebAssembly (WASM) and GPU-compute optimization, reported signing times of seconds, not microseconds even for Level 1 parameters. More recent implementations of actual browser-code variant for WebAuthn PassKey are routinely lss than 1 second [WebAuthn-PQC-Signature-size-constraints].

As a directly reproducible counter-data-point: the authors' own SQIsign-L1 WASM implementation, exercised end-to-end as a JWS signing operation, measures a repeatable average of 350ms each signature, measured on consumer device [PQC-Testbed-VC-Bench]. A WebGPU-accelerated variant of the same implementation -- which requires crossOriginIsolated:true (i.e., COOP/COEP response headers enabling SharedArrayBuffer, Atomics-synchronized cross-thread WASM linear memory access, and enhanced-precision performance.now()) -- reduces this further to a routine average of 155ms per signature, on the same hardware and browser. Both figures are independently reproducible against the live implementation at the cited testbed tab which enumerates sample size and full measurement methodology.

This measurement reflects a high-end consumer platform and should be read as an upper bound on currently-achievable browser performance, not as representative of lower-end mobile devices, older hardware, or the constrained authenticators and platform modules discussed above. Benchmarks on representative mid-tier and mobile hardware are planned and will be published at [PQC-Testbed-VC-Bench] as they become available. As of this writing, comparable measurements have not been confirmed on Safari, Firefox, or Edge; the WebGPU-accelerated path in particular is expected to vary with each browser's crossOriginIsolated:true enforcement and WebGPU compute-shader support, and should not be assumed portable without independent verification.

Speed: even at 350ms (WASM) or 155ms (WASM with WebGPU-acceleration), SQIsign-L1 signing remains slower than ML-DSA signing on comparable hardware. Implementers should treat both the early and current figures as implementation-dependent, not intrinsic to the algorithm, and should expect continued improvement as WASM (nodejs backend and browser frontend) and WebGPU-accelerated (browser-only) implementations mature.

Table 1 compares representative parameter sets; note that these schemes are at different stages of standardization and evaluation.

Table 1
Algorithm Public Key Size Signature Size PK + Sig Fits < 1024?
ML-DSA-44 1,312 bytes 2,420 bytes ❌ (3,732 total)
ML-DSA-65 1,952 bytes 3,293 bytes ❌ (5,245 total)
ML-DSA-87 2,592 bytes 4,595 bytes ❌ (7,187 total)
FN-DSA-512 897 bytes 666 bytes ❌ (1,563 total)
FN-DSA-1024 1,793 bytes 1,280 bytes ❌ (3,073 total)
SQIsign-L1 65 bytes 148 bytes ✅ (213 total)
SQIsign-L3 97 bytes 224 bytes ✅ (321 total)
SQIsign-L5 129 bytes 292 bytes ✅ (421 total)

1.1.2. Pressing Need: Limit or Stop 'Harvest now; decrypt later' Attacks

Adversaries are collecting encrypted data today to decrypt when quantum computers become available. The transition to post-quantum cryptography (PQC) is critical for ensuring long-term security of digital communications against adversaries equipped with large-scale quantum computers. The National Institute of Standards and Technology (NIST) has been leading standardization efforts, having selected initial PQC algorithms and continuing to evaluate additional candidates.

CBOR Object Signing and Encryption (COSE) [RFC9052] is specifically designed for constrained node networks and IoT environments where bandwidth, storage, and computational resources are limited. The compact nature of SQIsign makes it an ideal candidate for COSE deployments.

1.1.3. Unprecedented regulatory urgency: from theoretcial planning to legally binding enforcement

Regulatory urgency for post-quantum migration is not confined to a single jurisdiction. In the United States, Executive Order 14413 [EO14413] directs the continued acceleration of quantum-resistant cryptography adoption across federal systems and critical infrastructure. This order builds on the algorithm guidance established in [CNSA-2] which highlights the necessity to "...effectively deprecate the use of RSA, Diffie-Hellman (DH), and elliptic curve cryptography (ECDH and ECDSA) when mandated.", Page 4.

Outside North America, the United Arab Emirates' National Encryption Policy [UAE-NEP] established national requirements for encryption practice and migration planning as post-quantum algorithms mature and become standardized.

In the Asia-Pacific region, Singapore's Cyber Security Agency (CSA), in coordination with the Monetary Authority of Singapore (MAS), issued a Quantum-Safe Migration Handbook [SG-CSA-QSMH] that required operators of critical information infrastructure (CII) to submit a full migration plan by March 2027 and complete migration to quantum-resistant encryption by 2031.

In Europe the G7 (with CISA) released a call to action [G7-CISA] to governments and organizations to begin their PQC transition as soon as possible to avoid exposure to quantum risks and to provide a level of long-term protection of confidential data.

There's now a convergence across independently governed jurisdictions in North America, the Gulf region, and Southeast Asia. Harvest-now-decrypt-later is turning into a matter of near-term operational urgency worldwide rather than a single country's policy position, driving also need for compact, deployable PQC signature schemes such as SQIsign.

1.1.4. Direct usecase of SQIsign-L1 over existing NIST-approved algorithms: Verifiable Credentials Selective Disclosure Over Optical, BLE and other Constrained-Bandwidth Channels

1.1.4.1. Selective-Disclosure Credential Deployments

Selective-disclosure credential systems allow a holder to reveal only selected issuer-authenticated claims. The credential format and presentation protocol, rather than the COSE or JOSE signature algorithm alone, determine the resulting privacy properties.

For example, an issuer can sign a commitment structure over a set of claims. A holder may disclose a claim together with the information needed to verify that the claim is included in the issuer-signed structure. Depending on the construction, a presentation can include commitment openings, inclusion proofs, issuer identifiers, status information, device authentication, or other protocol-specific data.

1.1.4.2. Linkable claims selective disclosure

Re-use of a static issuer-signed credential structure can permit correlation between presentations. Correlation across presentations is required. Example: Hazardous-materials ("hazmat") shipping manifests are re-verified by carriers, first responders, and regulators at multiple points along a transport chain; confirming that each checkpoint is looking at the same declared shipment is necessary for safety and audit purposes. Other linkable examples include origin, materials, environmental performance, and recycling claims.

1.1.4.3. Unlinkable claims selective disclosure

Applications requiring presentation unlinkability need a protocol-level construction with an explicit unlinkability definition and threat model. Conventional digital signature schemes, including current PQC signature schemes, do not by themselves provide re-randomizable zero-knowledge presentations of signed claims.

Correlation across presentations are not required or wanted. Mobile driving licenses (mDLs) [USDOT49CFR172], as specified in [ISO18013-5], are the clearest example: a holder must not be traceable across unrelated age- or identity-verification events, even by colluding verifiers.

Classical algorithms (pre-PQC) like BBS/BBS+ solve this natively and efficiently (by added size in bytes): a single signature supports an unbounded number of statistically independent, re-randomizable zero-knowledge proofs over the same underlying claims. It is unsuitable for PQC deployment, however, for a reason distinct from unlinkability itself: BBS/BBS+ security rests on pairing-friendly elliptic curves. Elliptic curves are broken by Shor's algorithm, so unforgeability -- not merely unlinkability -- collapses against a quantum adversary. BBS/BBS+ is therefore excluded from consideration entirely, not merely deprioritized.

Some designs may issue multiple independently usable issuer-authenticated artifacts to a holder, for example the new Digital Product Passport [DPP]. In such designs, compact signatures can reduce issuance bandwidth, holder storage, and presentation size. The benefit is especially relevant where credentials are transferred using constrained channels, such as QR codes, NFC, BLE, or low-bandwidth networks.

Under this pattern, per-presentation cost scales as:

cost = (claims revealed) x (batch depth) x (signature size)

This multiplication is tractable at any scale only with a small per-signature size. Table 2 summarizes which combination of approach and algorithm remains viable as claim count grows:

Table 2
Disclosure mode Viable algorithm(s) Constraint
Linkable (any claim count) FN-DSA, ML-DSA, or SQIsign, any level Signature cost paid once; size doesn't scale with claims
Unlinkable, small claim count ML-DSA-/FN-DSA-class, or SQIsign-L1 Tractable only while claims x batch depth stays small
Unlinkable, large claim count SQIsign-L1 ML-DSA-/FN-DSA-class signature sizes make claims x batch depth x sig-size prohibitive; SQIsign-L1's ECDSA/EdDSA-class size is the only presently known PQC-safe option that stays affordable

This document does not define a selective-disclosure credential format, unlinkability mechanism, commitment scheme, revocation mechanism, or presentation protocol. Such mechanisms are application- and ecosystem-specific, and nothing in this section shall diminish the applicability of FN-DSA or ML-DSA for linkable SD, or wherever NFC, fast-BLE, or other non-optical transports are available.

1.2. Scope and Status

This document specifies interoperable COSE and JOSE representations for a defined version of SQIsign. It does not make an independent determination of the cryptographic suitability of SQIsign. This document is published on the Standards track rather than Informational Track.

This document does not represent Working Group consensus on algorithm innovation. The COSE and JOSE working groups focus on algorithm integration and encoding, not cryptographic algorithm design. The cryptographic properties of SQIsign are being evaluated through NIST's process and academic peer review.

If a WG wishes to pursue this as Standards Track, the document’s best support is a stable, precise, interoperable encoding specification supported by:

  1. Algorithm Maturity: SQIsign is currently undergoing evaluation in NIST's on-ramp process

  2. Continued Cryptanalysis: The algorithm has active ongoing review by the cryptographic research community, including the IRTF CFRG

  3. High anticipated demand: This specification enables experimentation and early deployment to gather implementation experience

1.3. Relationship to Other Work

This document follows the precedent established by [I-D.ietf-cose-falcon] and [I-D.ietf-cose-dilithium] for integrating NIST PQC candidate algorithms into COSE and JOSE. The structure and approach are intentionally aligned to provide consistency across post-quantum signature scheme integrations.

1.4. Constrained Device Applicability

SQIsign is particularly attractive for:

  • QR code printers, any display screen, scanners especially mobile consumer-grade

  • IoT sensors with limited flash memory

  • Firmware updates over low-bandwidth networks (LoRaWAN, NB-IoT)

  • Embedded certificates burned into the OS, or added to the secure enclave of a constrained device

  • Blockchain and DLT where transaction size affects gas fees

  • Satellite communications with bandwidth constraints

2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

This document uses the following terms:

3. Cryptanalytic Resistance: SIDH/SIKE Attacks Do Not Apply

3.1. SIKE Vulnerability (The "Torsion Point" Attack) of 2022

SIKE (Supersingular Isogeny Key Encapsulation) was a key exchange, more specifically, a Key Encapsulation Mechanism (KEM). In the SIKE protocol, users had to share more than just the target elliptic curve. To make the math work for key exchange, they shared the images of specific points (called torsion points) under the secret isogeny.

  • The Info: If the secret isogeny is 𝜙, SIKE gave away 𝜙(𝑃) and 𝜙(𝑄) for specific basis points 𝑃 and 𝑄.

  • The Break: In 2022, Castryck and Decru showed that this auxiliary information allowed an attacker to allowed an attacker to construct a higher-dimensional abelian variety linking the public data. In this setting, the secret isogeny can be recovered efficiently using techniques based on Kani’s results on isogenies between products of elliptic curves.

  • The Oversight: For years, cryptanalysts thought this extra info was harmless. Related techniques existed in the algebraic geometry literature but had not previously been applied in this cryptographic context.

3.2. Why SQISign appears unaffected by the SIKE Vulnerability

  • SQIsign is a signature scheme in which the prover demonstrates knowledge of an isogeny through a zero-knowledge protocol. Unlike SIDH/SIKE, it does not publish images of torsion basis points under secret isogenies.

  • Castryck–Decru attack relies critically on this auxiliary torsion-point information to construct additional structure (e.g., via abelian surfaces) that enables efficient recovery of the secret isogeny.

  • SQIsign does not provide such auxiliary data, so these techniques do not directly apply. Attacks would instead need to solve instances of the isogeny path problem or related problems in the endomorphism ring, for which no comparable shortcut is currently known.

4. SQIsign Algorithm Overview

4.1. Cryptographic Foundation

SQIsign is based on the hardness of finding isogenies between supersingular elliptic curves over finite fields. The security assumption relies primarily on the difficulty of the Isogeny Path Problem

Unlike lattice-based schemes, isogeny-based cryptography offers:

  • Smaller key and signature sizes

  • Algebraic structure based on elliptic curve isogenies

  • Different security assumptions (diversification from lattice-based schemes)

4.2. Security Levels

SQIsign is defined with three parameter sets corresponding to NIST security levels:

Table 3
Parameter Set NIST Level Public Key Signature Quantum Security (estimated)
SQIsign-L1 I 65 bytes 148 bytes ~128 bits
SQIsign-L3 III 97 bytes 224 bytes ~192 bits
SQIsign-L5 V 129 bytes 292 bytes ~256 bits

4.3. Performance Characteristics

  • Signing: Computationally intensive relative to lattice schemes in unoptimized reference code; substantially faster in optimized WASM/WebGPU browser implementations (see [PQC-Testbed-VC-Bench]).

  • Verification: Moderate computational cost

  • Key Generation: Intensive computation required

  • Size: Exceptional efficiency: substantially smaller than many lattice-based alternatives at comparable security levels

Recommended Use Cases: - Sign-once, verify-many scenarios (firmware, certificates) - Bandwidth-constrained environments - Storage-limited devices - Applications where signature/key size dominates performance considerations

4.4. SQIsign Variants and the Post-SIKE Landscape

While the SQIsign team initially focused on improving the core algorithm, the 2022 SIKE vulnerability catalyzed broader research into higher-dimensional algebraic geometry, particularly investigating improvements to key and signature generation speed—widely viewed as implementation bottlenecks.

This interest has sparked an evolution of SQIsign variants, all still based on the baseline algorithm currently competing in NIST's Round 3. Remarkably, two independent groups published dimension-2 variants on the same day (May 13, 2024), with a third appearing the following day—demonstrating the rapid, simultaneous evolution of the field following the 2022 SIKE breakthrough.

Given this dynamic environment, readers interested in SQIsign's future will benefit from this summary, which we intend to update with each revision of this standards-track submission.

The key takeaway is that researchers have repurposed the higher-dimensional techniques from the SIKE cryptanalysis to optimize SQIsign variants with faster signing and potentially smaller sizes, while each group attempts to maintain equivalent post-quantum security levels.

Variants can be classified primarily by the geometric dimensions they employ:

4.4.1. Core SQIsign (Dimension 1)

The baseline algorithm currently competing in NIST's Round 3. The SQIsign team, in cooperation with IBM researchers, actively maintains and tunes this version. Recent updates focus on reducing memory footprints and accelerating core algebraic operations for practical implementation. However, NIST's current process permits only minor "tweaks" rather than substantial algorithmic changes.

4.4.2. Multi-dimensional variants

  • SQIsignHD [SQIsignHD] dramatically shrunk signature sizes, simplified verification.

  • SQIsign2D-West [SQIsign2D-West] prioritized a rigorous security proof over raw speed.

  • SQIsign2D-East [SQIsign2D-East] fast 2D verification using a generalized random isogeny algorithm.

  • SQIPrime [SQIPrime]: Offers two sub-variants with different dimension trade-offs:

    • SQIPrime2D: Uses only dimension 2 non-smooth challenge isogenies, avoiding the dimension 4 computations required by SQIsignHD. More efficient while remaining highly compact compared to non-isogeny PQC schemes.

    • SQIPrime4D: Uses dimension 4 isogenies for response representation, prioritizing maximum compactness at the cost of exponentially higher runtime. Despite the paper's title, this sub-variant represents the authors' exploration before settling on the 2D approach.

5. COSE Integration

This section defines the identifiers for SQIsign in COSE [RFC9053]. This section defines identifiers and parameters for representing SQIsign keys and signatures in COSE [RFC9052], including a new COSE key type, key-type-specific key parameters, and algorithm identifiers to be registered in the IANA "COSE Algorithms" registry [RFC9053].

5.1. SQIsign Algorithms

This document defines the following COSE algorithm identifiers. Values are suggested for early allocation and are subject to confirmation by IANA (see IANA Considerations).

Table 4
Name Description Value (TBD)
SQIsign-L1 SQIsign, NIST PQC Security Category 1 -61
SQIsign-L3 SQIsign, NIST PQC Security Category 3 -62
SQIsign-L5 SQIsign, NIST PQC Security Category 5 -63

5.2. SQIsign Key Types

A new COSE key type is defined for SQIsign, with the name "SQIsign" and value TBD-KTY, to be assigned from the IANA "COSE Key Types" registry.

5.3. SQIsign Key Parameters

SQIsign keys use the COSE_Key common parameters defined in Section 7.1 of [RFC9052], with the following specific assignments:

  • The 'kty' parameter (1) MUST be TBD-KTY (*).

  • The 'alg' parameter (3) MUST be -61 (SQIsign-L1), -62 (SQIsign-L3), or -63 (SQIsign-L5).

(*) [RFC Editor Note: Please replace TBD-KTY with the next available positive integer integer assigned by IANA in the COSE Key Types registry, and remove this note.]

5.4. SQIsign-Specific Key Parameters

The following key-type-specific parameters are defined for kty = SQIsign. As with other key types (e.g., OKP), these labels are scoped to kty = SQIsign and do not collide with parameters of other key types.

| Key Parameter | Label | CBOR Type | Description | |---------------|-------|-----------|-------------| | pub | -1 | bstr | SQIsign public key | | priv | -2 | bstr | *SQIsign private key (sensitive) | *MUST NOT appear in a public COSE_Key and MUST be handled as sensitive key material

5.5. COSE Key Format Examples

Examples use CBOR diagnostic notation (Section 8 of [RFC8949]). TBD-KTY denotes the value to be assigned to the SQIsign key type by IANA. Key material is truncated for readability.

5.5.1. Public Key (COSE_Key)

cbor-diag { 1: TBD-KTY, / kty: SQIsign / 3: -61, / alg: SQIsign-L1 / -1: h'[PUBLIC_KEY]' / pub: SQIsign public key bytes / }

5.5.2. Private Key (COSE_Key)

cbor-diag { 1: TBD-KTY, / kty: SQIsign / 3: -61, / alg: SQIsign-L1 / -1: h'[PUBLIC_KEY]', / pub: SQIsign public key bytes / -2: h'[PRIVATE_KEY]' / priv: SQIsign private key bytes / }

5.6. COSE Signature Format

SQIsign signatures in COSE follow the standard COSE_Sign1 structure [RFC9052]:

COSE_Sign1 = [ protected: bstr .cbor header_map, unprotected: header_map, payload: bstr / nil, signature: bstr ]

The signature field contains the raw SQIsign signature bytes.

5.6.1. Protected Headers

The protected header MUST include:

cbor-diag { 1: -61 / alg: SQIsign-L1, -62 for L3, -63 for L5 / }

5.6.2. Example COSE_Sign1 Structure

cbor-diag 18( / COSE_Sign1 tag / [ h'A10139003C', / protected: {"alg": -61} / {}, / unprotected / h'546869732069732074686520636F6E74656E742E', / payload / h'[SQISIGN_SIGNATURE_BYTES]' / signature / ] )

6. JOSE Integration

6.1. JSON Web Signature (JWS) Algorithm Registration

The following algorithm identifiers are registered for use in the JWS "alg" header parameter for JSON Web Signatures [RFC7515]:

Table 5
Algorithm Name Description Implementation Requirements
SQIsign-L1 SQIsign NIST Level I Optional
SQIsign-L3 SQIsign NIST Level III Optional
SQIsign-L5 SQIsign NIST Level V Optional

6.2. JSON Web Key (JWK) Representation

SQIsign keys are represented in JWK [RFC7517] format as follows:

6.2.1. Public Key Parameters

Table 6
Parameter Type Description
kty string Key type: "SQIsign"
alg string Algorithm: "SQIsign-L1", "SQIsign-L3", or "SQIsign-L5"
pub string Base64url-encoded public key
kid string Key ID (optional)
use string Public key use: "sig" (optional)
key_ops array Key operations: [verify] (optional)

6.2.2. Private Key Parameters

Private keys include all public key parameters plus:

Table 7
Parameter Type Description
priv string Base64url-encoded private key

6.3. JWK Examples

6.3.1. Public Key (JWK) Example

json { "kty": "SQIsign", "alg": "SQIsign-L1", "pub": "KxtQx8s8RcBEU67wr57K37fdPEztN4M8NUC_\ 5xZuqgMwkaeJhM94YHi_-2UsQllbnmm-W4XFSLm2hUwiMylrAh0", "kid": "2027-01-device-key", "use": "sig", "key_ops": ["verify"] }

6.3.2. Private Key (JWK) Example

json { "kty": "SQIsign", "alg": "SQIsign-L1", "pub": "KxtQx8s8RcBEU67wr57K37fdPEztN4M8NUC_\ 5xZuqgMwkaeJhM94YHi_-2UsQllbnmm-W4XFSLm2hUwiMylrAh0", "priv": "KxtQx8s8RcBEU67wr57K37fdPEztN4M8NUC_5xZuqgMwkaeJhM94YHi_\ -2UsQllbnmm-W4XFSLm2hUwiMylrAh1VwP9vNkBZH0Bjj2wc-\ p7sUgQAAAAAAAAAAAAAAAAAAN68tviJbcCpQ84fh-4IJB4-\ ____________________P38m3fKOhfhMspQU9GmA4CD5___\ _______________________________________________\ ___________wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\ AAAAAAA5cP9aha40v-8mFd_bdAgpR93Ug2iPhu4_NxG97C7\ 8wBvVMGOrQTCli7NxrR2KlPZR1AC5VddGf4p-ZjCzrWfAJv\ xhEh4uOKXq1MmuS9TwZGuz1YIYMIguu1wqjdmfaQAfOmK2g\ WWO3vcld5s7GR2AcrTv65ocK_pVUWY8eJDcQA", "kid": "2027-01-device-key", "use": "sig", "key_ops": ["sign"] }

6.4. JWS Compact Serialization

A JWS using SQIsign follows the standard compact serialization:

BASE64URL(UTF8(JWS Protected Header)) || '.' || BASE64URL(JWS Payload) || '.' || BASE64URL(JWS Signature)

6.4.1. Example JWS Protected Header

json { "alg": "SQIsign-L1", "typ": "JWT" }

Base64url-encoded: eyJhbGciOiJTUUlzaWduLUwxIiwidHlwIjoiSldUIn0

6.4.2. Complete JWS Example

eyJhbGciOiJTUUlzaWduLUwxIiwidHlwIjoiSldUIn0 . [BASE64URL_PAYLOAD] . [BASE64URL_SQISIGN_SIGNATURE]

7. Implementation Considerations

7.1. Signature and Key Generation

Implementations MUST follow the SQIsign specification [SQIsign-Spec] for:

  • Key pair generation

  • Signature generation

  • Signature verification

7.2. Randomness Requirements

SQIsign signature generation requires high-quality randomness. Implementations MUST use a cryptographically secure random number generator (CSRNG) compliant with [RFC4086] or equivalent.

7.3. Side-Channel Protections

Implementations SHOULD implement protections against:

  • Timing attacks

  • Power analysis

  • Fault injection attacks

Particularly for constrained devices deployed in physically accessible environments.

7.4. Performance Trade-offs

Implementers should be aware:

  • Signing is computationally expensive: Consider pre-signing or batch operations

  • Verification is moderate: Suitable for resource-constrained verifiers

  • Size is exceptional: Minimizes bandwidth and storage

7.5. Interoperability Testing

Early implementations SHOULD participate in interoperability testing to ensure:

  • Consistent signature generation and verification

  • Proper encoding in COSE and JOSE formats

  • Cross-platform compatibility

7.6. Performance testing under real-world scenarios

  • public metrics, interoperability and performance testing of the proposed WASM versions can be evaluated on a live testbed [PQC-Testbed].

8. Security Considerations

8.1. Algorithm Security

The security of SQIsign relies primarily on the hardness of finding isogenies between supersingular elliptic curves.

These assumptions are different from lattice-based schemes, providing cryptographic diversity in the post-quantum landscape.

8.2. Quantum Security

SQIsign is designed to resist attacks by large-scale quantum computers. The three parameter sets provide security equivalent to AES-128, AES-192, and AES-256 against both classical and quantum adversaries.

8.3. Cryptanalysis and Algorithm Maturity

As of this writing, SQIsign is undergoing active cryptanalytic review:

  • NIST Round 3 evaluation: [NIST-3rd-round-candidates]

  • Academic research: Ongoing analysis of isogeny-based cryptography

  • Known attacks: No attacks are currently known that recover private keys for the standardized parameter sets within their claimed security levels. However, the scheme and its underlying assumptions remain under active study.

Implementers are advised: - Monitor NIST announcements and updates - Follow academic literature on isogeny cryptanalysis - Be prepared to deprecate or update as cryptanalysis evolves

8.4. Implementation Security

8.4.1. Random Number Generation

Poor randomness can completely compromise SQIsign security. Implementations MUST use robust CSRNGs, especially on constrained devices with limited entropy sources.

8.4.2. Side-Channel Resistance

Constrained devices may be physically accessible to attackers. Implementations SHOULD:

  • Use constant-time algorithms where possible

  • Implement countermeasures against DPA/SPA

  • Consider fault attack mitigations

8.4.3. Key Management

  • Private keys MUST be protected with appropriate access controls

  • Consider hardware security modules (HSMs) or secure elements for key storage

  • Implement key rotation policies appropriate to the deployment

8.5. Cryptographic Agility

Organizations deploying SQIsign SHOULD:

  • Maintain hybrid deployments with classical algorithms during transition

  • Plan for algorithm migration if cryptanalysis reveals weaknesses

  • Monitor NIST and IRTF guidance on PQC deployment

8.6. Constrained Device Specific Risks

IoT devices face unique challenges:

  • Physical access: Devices may be deployed in hostile environments

  • Limited update capability: Firmware updates may be infrequent or impossible

  • Long deployment lifetimes: Devices may operate for 10+ years

Design systems with: - Defense in depth (multiple security layers) - Remote update capability when possible - Graceful degradation if algorithm is compromised

9. IANA Considerations

9.1. Additions to Existing Registries

IANA is requested to add the following entries to the COSE and JOSE registries. The following completed registration actions are provided as described in [RFC9053] and [RFC9054].

9.1.1. New COSE Algorithms

IANA is requested to register the following entries in the "COSE Algorithms" registry:

Table 8
Name Value Description Capabilities Change Cont Ref Rec'd
SQIsign-L1 -61 SQIsign NIST L I kty IETF THIS-RFC No
SQIsign-L3 -62 SQIsign NIST L III kty IETF THIS-RFC No
SQIsign-L5 -63 SQIsign NIST L V kty IETF THIS-RFC No

9.1.2. New COSE Key Types

IANA is requested to register the following entry in the "COSE Key Types" registry:

Table 9
Name Value Description Capabilities Change Cont Ref
SQIsign *TBD-KTY SQIsign pub key sign, verify IETF THIS-RFC

  • [RFC Editor Note: Please replace TBD-KTY with the next available positive integer assigned by IANA in the COSE Key Types registry.]

9.1.3. New COSE Key Type Parameters

IANA is requested to register the following entries in the "COSE Key Type Parameters" registry:

Table 10
Key Type Name Label CBOR Type Desc Change Cont Reference
*TBD-KTY pub -1 bstr SQIsign Public key IETF THIS-RFC
*TBD-KTY priv -2 bstr SQIsign Private key IETF THIS-RFC

  • [RFC Editor Note: Please replace TBD-KTY with the numeric value assigned in the COSE Key Types registry above.]

9.1.4. New JWS Algorithms

IANA is requested to register the following entries in the "JSON Web Signature and Encryption Algorithms" registry:

Table 11
Algorithm Name Desc Impl Req Change Cont Ref Recommended
SQIsign-L1 SQIsign NIST L I Optional IETF THIS-RFC No
SQIsign-L3 SQIsign NIST L III Optional IETF THIS-RFC No
SQIsign-L5 SQIsign NIST L V Optional IETF THIS-RFC No

9.1.5. New JSON Web Key Types

IANA is requested to register the following entry in the "JSON Web Key Types" registry:

Table 12
"kty" Param Value Key Type Desc Change Cont Reference
SQIsign SQIsign public key IETF THIS-RFC

9.1.6. New JSON Web Key Parameters

IANA is requested to register the following entries in the "JSON Web Key Parameters" registry:

Table 13
Param Name Desc Used with "kty" Val Change Cont Reference
pub Public key SQIsign IETF THIS-RFC
priv Private key SQIsign IETF THIS-RFC

10. Acknowledgments

The authors would like to thank:

This work builds upon the template established by [I-D.ietf-cose-falcon] and similar PQC integration efforts.

11. References

This document has a normative reference to [RFC9053] and [RFC9054], both currently at Informational status, which is a lower maturity level than required for normative references from a Standards Track document. This is a conscious choice by the authors; see [RFC3967] and [RFC4897] for background on this practice.

11.1. Normative References

Populated automatically from metadata

11.2. Informative References

Populated automatically from metadata

12. References

12.1. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC7515]
Jones, M., Bradley, J., and N. Sakimura, "JSON Web Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, , <https://www.rfc-editor.org/rfc/rfc7515>.
[RFC7517]
Jones, M., "JSON Web Key (JWK)", RFC 7517, DOI 10.17487/RFC7517, , <https://www.rfc-editor.org/rfc/rfc7517>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC9052]
Schaad, J., "CBOR Object Signing and Encryption (COSE): Structures and Process", STD 96, RFC 9052, DOI 10.17487/RFC9052, , <https://www.rfc-editor.org/rfc/rfc9052>.
[RFC9053]
Schaad, J., "CBOR Object Signing and Encryption (COSE): Initial Algorithms", RFC 9053, DOI 10.17487/RFC9053, , <https://www.rfc-editor.org/rfc/rfc9053>.
[RFC9054]
Schaad, J., "CBOR Object Signing and Encryption (COSE): Hash Algorithms", RFC 9054, DOI 10.17487/RFC9054, , <https://www.rfc-editor.org/rfc/rfc9054>.

12.2. Informative References

[CNSA-2]
National Security Agency, "Commercial National Security Algorithm Suite 2.0", , <https://media.defense.gov/2025/May/30/2003728741/-1/-1/0/CSA_CNSA_2.0_ALGORITHMS.PDF>.
[CTAP2-spec]
Fido Alliance, "Client to Authenticator Protocol (CTAP) Section 8.1.4 Message and packet structure", , <https://fidoalliance.org/specs/fido-v2.0-id-20180227/fido-client-to-authenticator-protocol-v2.0-id-20180227.html>.
[DPP]
European Commission, Directorate-General for Internal Market, Industry, "Digital Product Passport (DPP)", , <https://single-market-economy.ec.europa.eu/single-market/digital-product-passport_en>.
[EO14413]
US Executive Office of the President, "Executive Order 14413: Ushering in the next frontier of quantum", , <https://www.whitehouse.gov/presidential-actions/2026/06/ushering-in-the-next-frontier-of-quantum-innovation/>.
[G7-CISA]
Agence nationale de la sécurité des systèmes d'information, "Preparing for the Post-Quantum Era: A Call to Action", , <https://cyber.gouv.fr/en/publications/jointly-led-international-publications/preparing-for-the-post-quantum-era-a-call-to-action/>.
[I-D.ietf-cose-dilithium]
Prorock, M. and O. Steele, "ML-DSA for JOSE and COSE", Work in Progress, Internet-Draft, draft-ietf-cose-dilithium-11, , <https://datatracker.ietf.org/doc/html/draft-ietf-cose-dilithium-11>.
[I-D.ietf-cose-falcon]
Prorock, M., Steele, O., and H. Tschofenig, "FN-DSA for JOSE and COSE", Work in Progress, Internet-Draft, draft-ietf-cose-falcon-04, , <https://datatracker.ietf.org/doc/html/draft-ietf-cose-falcon-04>.
[ISO18013-5]
ISO, "Personal identification — ISO-compliant Mobile Driving License", , <https://www.iso.org/standard/91081.html>.
[NIST-3rd-round-candidates]
NIST, "Nine Candidates Advance to the Third Round of the Additional Digital Signatures for the PQC Standardization Process", , <https://csrc.nist.gov/News/2026/nist-advances-9-candidates-to-the-3rd-round-of-pqc>.
[PQC-Testbed]
RustyKey®, "PQC RustyKey® Testbed", , <https://pqc.rustykey.me>.
[PQC-Testbed-VC-Bench]
RustyKey®, "PQC RustyKey® Testbed — Verifiable Credentials Tab: SQIsign-L1 WASM and WebGPU-Accelerated JWS Signing Benchmarks", Measured on MacBook Pro, Apple M4 Max, 128GB RAM, macOS 26.6.2, Chrome 152.0.7977.65 (arm64), , <https://pqc.rustykey.me/#verifiable_credentials>.
[RFC3967]
Bush, R. and T. Narten, "Clarifying when Standards Track Documents may Refer Normatively to Documents at a Lower Level", BCP 97, RFC 3967, DOI 10.17487/RFC3967, , <https://www.rfc-editor.org/rfc/rfc3967>.
[RFC4086]
Eastlake 3rd, D., Schiller, J., and S. Crocker, "Randomness Requirements for Security", BCP 106, RFC 4086, DOI 10.17487/RFC4086, , <https://www.rfc-editor.org/rfc/rfc4086>.
[RFC4897]
Klensin, J. and S. Hartman, "Handling Normative References to Standards-Track Documents", BCP 97, RFC 4897, DOI 10.17487/RFC4897, , <https://www.rfc-editor.org/rfc/rfc4897>.
[RFC8949]
Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", STD 94, RFC 8949, DOI 10.17487/RFC8949, , <https://www.rfc-editor.org/rfc/rfc8949>.
[SG-CSA-QSMH]
Cyber Security Agency of Singapore (CSA), "Quantum-Safe Migration Handbook and Quantum Readiness Index", , <https://www.csa.gov.sg/resources/publications/quantum-safe-handbook-and-quantum-readiness-index/>.
[SQIPrime]
Max Duparc, Tako Boris Fouotsa, "SQIPrime: A dimension 2 variant of SQISignHD with non-smooth challenge isogenies", , <https://eprint.iacr.org/2024/773>.
[SQIsign2D-East]
Kohei Nakagawa, Hiroshi Onuki, "SQIsign2D-East: A New Signature Scheme Using 2-dimensional Isogenies", , <https://eprint.iacr.org/2024/771>.
[SQIsign2D-West]
Andrea Basso, Luca De Feo, Pierrick Dartois, Antonin Leroux, Luciano Maino, Giacomo Pope, Damien Robert, Benjamin Wesolowski, "SQIsign2D-West: The Fast, the Small, and the Safer", , <https://eprint.iacr.org/2024/760>.
[SQIsign-Analysis]
IACR ePrint Archive, ""SQIsign: Compact Post-Quantum Signatures from Quaternions and Isogenies"", , <https://eprint.iacr.org/2020/1240>.
[SQIsign-Spec]
SQIsign team, "Algorithm specifications andsupporting documentation Version 2.0.1", , <https://sqisign.org/spec/sqisign-20250707.pdf>.
[SQIsignHD]
Pierrick Dartois, Antonin Leroux, Damien Robert, Benjamin Wesolowski, "SQISignHD: New Dimensions in Cryptography", , <https://eprint.iacr.org/2023/436>.
[UAE-NEP]
United Arab Emirates Government, Cyber Security Council, "The National Cyber Security Policy for Artificial Intelligence", , <https://u.ae/en/about-the-uae/strategies-initiatives-and-awards/policies/cyber-activities/The-National-Cyber-Security-Policy-for-Artificial-Intelligence>.
[USDOT49CFR172]
U.S. Department of Transportation, "Hazmat Transportation Requirements", , <https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/training/hazmat/69186/hazmat-transportation-reqmts-web-final.pdf>.
[WebAuthn-PQC-Signature-size-constraints]
University of Quantum Science, "WebAuthn PQC Signature size constraints", , <https://www.npmjs.com/package/quantum-resistant-rustykey>.

Appendix A. Test Vectors

Vectors use NIST KAT count = 0 from upstream SQIsign response files (PQCsignKAT_*_SQIsign_lvl*.rsp). The same 32-byte message appears at each security level so implementers can compare keys and signatures. Algorithm identifiers -61, -62, and -63 map to SQIsign-L1, SQIsign-L3, and SQIsign-L5 respectively.

A.1. SQIsign-L1 Test Vectors

A.1.1. Example 1: Simple Message Signing

The following test vector exhibits a SQIsign Level I signature over a short message.

Message (hex): d81c4d8d734fcbfbeade3d3f8a039faa2a2c9957e835ad55b2 \ 2e75bf57bb556ac8 Message (ASCII): MsO=?*,W5U.uWUj

Public Key (hex): 07CCD21425136F6E865E497D2D4D208F0054AD81372066E \ 817480787AAF7B2029550C89E892D618CE3230F23510BFBE68FCCDDAEA51DB1436 \ B462ADFAF008A010B Public Key (Base64url): B8zSFCUTb26GXkl9LU0gjwBUrYE3IGboF0gHh6r3s \ gKVUMieiS1hjOMjDyNRC_vmj8zdrqUdsUNrRirfrwCKAQs

Signature (hex): 84228651f271b0f39f2f19f2e8718f31ed3365ac9e5cb303 \ afe663d0cfc11f0455d891b0ca6c7e653f9ba2667730bb77befe1b1a3182840428 \ 4af8fd7baacc010001d974b5ca671ff65708d8b462a5a84a1443ee9b5fed721876 \ 7c9d85ceed04db0a69a2f6ec3be835b3b2624b9a0df68837ad00bcacc27d1ec806 \ a44840267471d86eff3447018adb0a6551ee8322ab30010202 Signature (Base64url): hCKGUfJxsPOfLxny6HGPMe0zZayeXLMDr-Zj0M_BHw \ RV2JGwymx-ZT-bomZ3MLt3vv4bGjGChAQoSvj9e6rMAQAB2XS1ymcf9lcI2LRipahK \ FEPum1_tchh2fJ2Fzu0E2wppovbsO-g1s7JiS5oN9og3rQC8rMJ9HsgGpEhAJnRx2G \ 7_NEcBitsKZVHugyKrMAECAg

A.1.2. COSE_Sign1 Complete Example

cbor-diag 18( [ h'a10139003c', / protected: {"alg": -61} / {}, / unprotected / h'd81c4d8d734fcbfbeade3d3f8a039faa2a2c9957e835ad55b22e75bf57bb \ 556ac8', / payload / h'84228651f271b0f39f2f19f2e8718f31ed3365ac9e5cb303afe663d0cfc1 \ 1f0455d891b0ca6c7e653f9ba2667730bb77befe1b1a31828404284af8fd7b \ aacc010001d974b5ca671ff65708d8b462a5a84a1443ee9b5fed7218767c9d \ 85ceed04db0a69a2f6ec3be835b3b2624b9a0df68837ad00bcacc27d1ec806 \ a44840267471d86eff3447018adb0a6551ee8322ab30010202' ] )

A.1.3. JWS Complete Example

eyJhbGciOiJTUUlzaWduLUwxIiwidHlwIjoiSldUIn0 . 2BxNjXNPy_vq3j0_igOfqiosmVfoNa1Vsi51v1e7VWrI . hCKGUfJxsPOfLxny6HGPMe0zZayeXLMDr-Zj0M_BHwRV2JGwymx-ZT-bomZ3MLt3vv \ 4bGjGChAQoSvj9e6rMAQAB2XS1ymcf9lcI2LRipahKFEPum1_tchh2fJ2Fzu0E2wpp \ ovbsO-g1s7JiS5oN9og3rQC8rMJ9HsgGpEhAJnRx2G7_NEcBitsKZVHugyKrMAECAg

A.2. SQIsign-L3 Test Vectors

A.2.1. Example 1: Simple Message Signing

The following test vector exhibits a SQIsign Level III signature over a short message (NIST KAT count = 0; COSE/JOSE algorithm -62).

Message (hex): D81C4D8D734FCBFBEADE3D3F8A039FAA2A2C9957E835AD55B22E75BF \ 57BB556AC8 Message (ASCII): MsO=?*,W5U.uWUj

Public Key (hex): C32377D6F6D70729884A7F6877EF4791E35D21F751A3E96DE23F9 \ A7A3C01BCD8A5F146DC19E4E2AC63007457F97D8A40EE84AEE7564CA9A7FBE6200FD3E5 \ E55901BFC60EB25C50D39F5C91C96510556BAA22028DF76360841721A601D65E8D0F06 Public Key (Base64url): wyN31vbXBymISn9od-9HkeNdIfdRo-lt4j-aejwBvNil8Ub \ cGeTirGMAdFf5fYpA7oSu51ZMqaf75iAP0-XlWQG_xg6yXFDTn1yRyWUQVWuqIgKN92NghB \ chpgHWXo0PBg

Signature (hex): 0868CFBF275B8E7B19BF597D658D62CC913B9B2933E30A297288FB \ E687F6F6B8AC8AF7AA007F191386BB1A203CDDBC2BDB42792D05DA69A4507073D12B0BD \ C47E2B36BC4BA45C68791918281E578F2DC14294504726DCD4CA4C4565FBB89A1280004 \ 8C7B84746A2CBD8247248E248B70B51AE91994957857692A028D8F5CABABFC91E4BF1C5 \ D350219A0189C57DE4A7710D29E0364C79B2188449EC0397359430D594C7B5980CC6755 \ 1933A902D3C11F0FBD6DC39711D3E1F501159EE7FB85CE81B4CE24E1016006567DF4693 \ 15D513E73F69F6301664E6449AF9DCEB4000D15 Signature (Base64url): CGjPvydbjnsZv1l9ZY1izJE7mykz4wopcoj75of29risiveq \ AH8ZE4a7GiA83bwr20J5LQXaaaRQcHPRKwvcR-Kza8S6RcaHkZGCgeV48twUKUUEcm3NTKT \ EVl-7iaEoAASMe4R0aiy9gkckjiSLcLUa6RmUlXhXaSoCjY9cq6v8keS_HF01AhmgGJxX3k \ p3ENKeA2THmyGIRJ7AOXNZQw1ZTHtZgMxnVRkzqQLTwR8PvW3DlxHT4fUBFZ7n-4XOgbTOJ \ OEBYAZWffRpMV1RPnP2n2MBZk5kSa-dzrQADRU

A.2.2. COSE_Sign1 Complete Example

cbor-diag 18( [ h'a10139003d', / protected: {"alg": -62} / {}, / unprotected / h'd81c4d8d734fcbfbeade3d3f8a039faa2a2c995 \ 7e835ad55b22e75bf57bb556ac8', / payload / h'0868cfbf275b8e7b19bf597d658d62cc913b9b2 \ 933e30a297288fbe687f6f6b8ac8af7aa007f191386bb1a203cddbc2bdb42792 \ d05da69a4507073d12b0bdc47e2b36bc4ba45c68791918281e578f2dc1429450 \ 4726dcd4ca4c4565fbb89a12800048c7b84746a2cbd8247248e248b70b51ae91 \ 994957857692a028d8f5cababfc91e4bf1c5d350219a0189c57de4a7710d29e0 \ 364c79b2188449ec0397359430d594c7b5980cc67551933a902d3c11f0fbd6dc \ 39711d3e1f501159ee7fb85ce81b4ce24e1016006567df469315d513e73f69f6 \ 301664e6449af9dceb4000d15', / signature / ] )

A.2.3. JWS Complete Example

eyJhbGciOiJTUUlzaWduLUwzIiwidHlwIjoiSldUIn0 . 2BxNjXNPy_vq3j0_igOfqiosmVfoNa1Vsi51v1e7VWrI . CGjPvydbjnsZv1l9ZY1izJE7mykz4wopcoj75of29risiveqAH8ZE4a7GiA83bwr20J5LQXa \ aaRQcHPRKwvcR-Kza8S6RcaHkZGCgeV48twUKUUEcm3NTKTEVl-7iaEoAASMe4R0aiy9gkck \ jiSLcLUa6RmUlXhXaSoCjY9cq6v8keS_HF01AhmgGJxX3kp3ENKeA2THmyGIRJ7AOXNZQw1Z \ THtZgMxnVRkzqQLTwR8PvW3DlxHT4fUBFZ7n-4XOgbTOJOEBYAZWffRpMV1RPnP2n2MBZk5k \ Sa-dzrQADRU

A.3. SQIsign-L5 Test Vectors

A.3.1. Example 1: Simple Message Signing

The following test vector exhibits a SQIsign Level V signature over a short message (NIST KAT count = 0; COSE/JOSE algorithm -63).

Message (hex): D81C4D8D734FCBFBEADE3D3F8A039FAA2A2C9957E835AD55B22E75BF \ 57BB556AC8 Message (ASCII): MsO=?*,W5U.uWUj

Public Key (hex): 86FFA3B0F73D55A64D13C6F89F28D75FD17C5E2368E1D451127C1 \ 6D1A97CDB440E20333A233AD2F8E4D70187C8AE31602049ADE949A87F95E79DA4C456F5 \ D400B2485A96D04708A2F30046812B8D65A3BFBFDED0DD6563462F9E2BCE760CD753CAE \ 8471BEC7049EF28FFEFE859C15DAC49DB959AEE99842D97A380A70DD7330106 Public Key (Base64url): hv-jsPc9VaZNE8b4nyjXX9F8XiNo4dRREnwW0al820QOIDM \ 6IzrS-OTXAYfIrjFgIEmt6Umof5XnnaTEVvXUALJIWpbQRwii8wBGgSuNZaO_v97Q3WVjRi \ -eK852DNdTyuhHG-xwSe8o_-_oWcFdrEnblZrumYQtl6OApw3XMwEG

Signature (hex): 6B8EF5D7689A1EA1CFCE9C6F7495E309E9D1D1B03E61CD97088E67 \ 9C4901D0B6B6D38217F4AED6C44949B41F9AF80B43E84D0C91BDB1D00E06957BEBF30A5 \ 8012AD01E52CF7906CE197AD06696F7FCF756908EA980549E7C215D089BDE7117799F62 \ 8817A1B9C8FB7FEBFF7E9D9B776142460CFAAFC97D48A57E09E0DA378401000229CC8E1 \ B94E1F2F8AFDC42066BEACE076E3E70DD01F90C4D01DAC17BEC58743532848D438A87A5 \ 74D9DB940C17236AE3566281E27A99EFE5EE26E05B88A1D610A80B3AF38267D845C7FE3 \ 30F199B43794A9B2E14846924127366B8F6A1F0F24D3C4B54D79DBB61B098BF32D98EA8 \ 819F7BE4A5FFBA29E88B1A996C6CDFD32B048BC2ACFFA28870181447FCC8B6F97B63C47 \ CB013C6F3D84CBD07619A5C355B000911 Signature (Base64url): a47112iaHqHPzpxvdJXjCenR0bA-Yc2XCI5nnEkB0La204IX \ 9K7WxElJtB-a-AtD6E0Mkb2x0A4GlXvr8wpYASrQHlLPeQbOGXrQZpb3_PdWkI6pgFSefCF \ dCJvecRd5n2KIF6G5yPt_6_9-nZt3YUJGDPqvyX1IpX4J4No3hAEAAinMjhuU4fL4r9xCBm \ vqzgduPnDdAfkMTQHawXvsWHQ1MoSNQ4qHpXTZ25QMFyNq41ZigeJ6me_l7ibgW4ih1hCoC \ zrzgmfYRcf-Mw8Zm0N5SpsuFIRpJBJzZrj2ofDyTTxLVNedu2GwmL8y2Y6ogZ975KX_uino \ ixqZbGzf0ysEi8Ks_6KIcBgUR_zItvl7Y8R8sBPG89hMvQdhmlw1WwAJEQ

A.3.2. COSE_Sign1 Complete Example

cbor-diag 18( [ h'a10139003e', / protected: {"alg": -63} / {}, / unprotected / h'd81c4d8d734fcbfbeade3d3f8a039faa2a2c995 \ 7e835ad55b22e75bf57bb556ac8', / payload / h'6b8ef5d7689a1ea1cfce9c6f7495e309e9d1d1b \ 03e61cd97088e679c4901d0b6b6d38217f4aed6c44949b41f9af80b43e84d0c9 \ 1bdb1d00e06957bebf30a58012ad01e52cf7906ce197ad06696f7fcf756908ea \ 980549e7c215d089bde7117799f628817a1b9c8fb7febff7e9d9b776142460cf \ aafc97d48a57e09e0da378401000229cc8e1b94e1f2f8afdc42066beace076e3 \ e70dd01f90c4d01dac17bec58743532848d438a87a574d9db940c17236ae3566 \ 281e27a99efe5ee26e05b88a1d610a80b3af38267d845c7fe330f199b43794a9 \ b2e14846924127366b8f6a1f0f24d3c4b54d79dbb61b098bf32d98ea8819f7be \ 4a5ffba29e88b1a996c6cdfd32b048bc2acffa28870181447fcc8b6f97b63c47 \ cb013c6f3d84cbd07619a5c355b000911', / signature / ] )

A.3.3. JWS Complete Example

eyJhbGciOiJTUUlzaWduLUw1IiwidHlwIjoiSldUIn0 . 2BxNjXNPy_vq3j0_igOfqiosmVfoNa1Vsi51v1e7VWrI . a47112iaHqHPzpxvdJXjCenR0bA-Yc2XCI5nnEkB0La204IX9K7WxElJtB-a-AtD6E0Mkb2x \ 0A4GlXvr8wpYASrQHlLPeQbOGXrQZpb3_PdWkI6pgFSefCFdCJvecRd5n2KIF6G5yPt_6_9- \ nZt3YUJGDPqvyX1IpX4J4No3hAEAAinMjhuU4fL4r9xCBmvqzgduPnDdAfkMTQHawXvsWHQ1 \ MoSNQ4qHpXTZ25QMFyNq41ZigeJ6me_l7ibgW4ih1hCoCzrzgmfYRcf-Mw8Zm0N5SpsuFIRp \ JBJzZrj2ofDyTTxLVNedu2GwmL8y2Y6ogZ975KX_uinoixqZbGzf0ysEi8Ks_6KIcBgUR_zI \ tvl7Y8R8sBPG89hMvQdhmlw1WwAJEQ

Appendix B. Implementation Status

[RFC Editor: Please remove this section before publication]

This section records the status of known implementations at the time of writing.

B.1. Open Source Implementations

B.1.1. Reference Implementation

  • Organization: SQIsign team

  • Repository: https://github.com/SQISign/the-sqisign

  • Language: C

  • License: MIT

  • Status: Active development

  • COSE/JOSE Support: Not yet integrated

B.1.2. Rust Implementation

  • Organization: IETF - Community implementation

  • Repository: IETF

  • Language: Rust

  • License: IETF

  • COSE Support: Planned

  • Status: Development

B.2. Commercial Implementations

[RFC EDITOR: To be populated as vendors implement]

B.3. Interoperability Testing

  • Test Suite Location: IETF

  • Participating Organizations: IETF

Appendix C. Design Rationale

C.1. Algorithm Identifier Selection

The requested algorithm identifiers (-61, -62, -63) are:

  • In the Standards Action range (-255 to -1) per RFC 9053

  • Sequential for the three parameter sets

  • Not conflicting with existing registrations (verified against IANA COSE registry)

  • Consistent with the approach used for other PQC algorithms

C.2. Key Type Design

The SQIsign key type is intentionally simple:

  • Only two parameters (pub, priv) following minimalist design

  • Binary encoding (bstr) for efficiency

  • No algorithm-specific encoding—raw bytes from SQIsign spec

This approach: - Minimizes CBOR encoding overhead (critical for constrained devices) - Simplifies implementation - Provides future flexibility for parameter set evolution

Appendix D. Change Log

[RFC Editor Note:** Please remove this section before publication]

D.1. draft-mott-cose-sqisign-07

  • Added Section motivating SQIsign adoption via real-world VC selective-disclosure deployments (linkable: hazmat manifest unlinkable: mDL) constrained to consumer-device-readable QR codes, citing testbed comparison against FN-DSA-512.

  • In response to some direct feedback, removed "...back-of-envelope extrapolations, vaguely sourced statistics, some without an immutable or obvious authoritative citation than any reader may, or WG will try to follow".

  • Added international regulatory context to existing sections citing new country-level policy directives to support claims of cross-jurisdictional urgency and avoid single-country framing.

D.2. draft-mott-cose-sqisign versions prior to -07

  • added section "SQIsign Variants and the Post-SIKE Landscape"

  • Incorporated technical corrections and feedback from Luca De Feo

  • Updated the Abstract and Introduction to utilize more neutral, objective language

  • Removed vendor-specific branding in favor of generic cryptographic terminology

  • fixed various formatting issues

  • Added SQIsign-L3 and SQIsign-L5 COSE_Sign1 and JWS test vectors (algorithms -62 and -63)

  • Documented NIST KAT count = 0 byte values for cross-implementation checks

  • added informational resource for interactive working code public testbed

  • updated after SQISign advances to NIST round 3 with 8 other candidates

Author's Address

Antony R. Mott
RustyKey®
United States of America