Crate confium_composite 

Composite multi-algorithm signature aggregation.

Combines classical (Ed25519, ECDSA) and PQ (ML-DSA, SLH-DSA) signatures so that breaking either alone doesn’t break the composite. Used for PQ migration without breaking verifiers.

See TODO.roadmap/35-pq-composite-signatures.md for the full spec.

Example

use confium_composite::{CompositeSignature, build_ed25519_component, ed25519_verifier, ED25519};
use ed25519_dalek::{Signer, SigningKey};
use ed25519_dalek::rand_core::UnwrapErr;

let signing = SigningKey::generate(&mut UnwrapErr(getrandom::SysRng));
let message = b"hybrid sig demo";
let component = build_ed25519_component(&signing, message)?;
let composite = CompositeSignature::new(vec![component]);
let result = composite.verify(message, |alg, pk, msg, sig| {
    if alg == ED25519 { ed25519_verifier(alg, pk, msg, sig) }
    else { Err(format!("unknown algorithm: {alg}")) }
})?;
assert!(result.all_verified);

Modules

algorithm_ids

Standard composite algorithm IDs per IETF LAMPS COMPOSITE SIG draft.

cache

LRU cache for signature verification results.

cose

COSE_Sign1 — CBOR-encoded signature wrapper (RFC 8152).

Structs

ComponentResult

Per-component verification result.

ComponentSignature

A single component of a composite signature.

CompositeSignature

A composite signature — multiple components over the same message.

VerificationResult

Aggregate verification result.

Enums

CompositeError

Errors during composite signature operations.

Constants

ECDSA_P256

Algorithm identifier for ECDSA-P256 components (NIST P-256 + SHA-256).

ED25519

Algorithm identifier for Ed25519 components.

MLDSA65

Verify an ECDSA-P256 signature (NIST P-256 over SHA-256). The public key is encoded as SEC1 (compressed 33 bytes or uncompressed 65 bytes). The signature is DER-encoded per RFC 5480.

ML_DSA_65

Algorithm identifier for ML-DSA-65 components (placeholder; no real verifier).

Functions

build_ed25519_component

Build a real Ed25519 component signature. Used for testing and as a reference for plugin authors.

build_p256_component

Build a real ECDSA-P256 component signature (NIST P-256 over SHA-256). The signature is DER-encoded per RFC 5480; the public key is SEC1 (uncompressed, 65 bytes).

ed25519_verifier

Real Ed25519 verifier. Use as the verifier callback when the composite contains an Ed25519 component. Returns Ok if the Ed25519 component verifies.

p256_verifier