signWithWire static method

Future<({Uint8List sessionId, Uint8List signature, List<MlDsaSigningMessage> wireMessages})> signWithWire({ required List<MlDsaShare> shares, required Uint8List message, Uint8List? context, String? mithrilBridgePath, })

Threshold-sign and export Mithril wire round payloads (M3 beta).

Returns the combined signature plus canonical MlDsaSigningMessage values for dir-transport under round1/, round2/, round3/.

Implementation

static Future<({
  Uint8List signature,
  Uint8List sessionId,
  List<MlDsaSigningMessage> wireMessages,
})> signWithWire({
  required List<MlDsaShare> shares,
  required Uint8List message,
  Uint8List? context,
  String? mithrilBridgePath,
}) async {
  assertMlDsaShareSetConsistent(shares);
  final params = shares.first.params;
  if (params.scheme != SchemeId.mlDsa44ThresholdV1) {
    throw SchemeNotImplemented(
      'M2 Mithril bridge supports mlDsa44ThresholdV1 only; got ${params.scheme}',
    );
  }
  if (shares.length < params.t) {
    throw InsufficientShares(
      'Need at least ${params.t} shares, got ${shares.length}',
    );
  }

  final publicKeyBytes = await _derivePublicKey(
    params: params,
    ceremonySeed: shares.first.ceremonySeedBytes(),
    mithrilBridgePath: mithrilBridgePath,
  );
  final publicKey = MlDsaPublicKey.create(
    params: params,
    ceremonyId: shares.first.ceremonyId,
    publicKeyBytes: publicKeyBytes,
  );

  final active = shares
      .take(params.t)
      .map((s) => s.mithrilPartyId)
      .toList()
    ..sort();

  final wire = await mithrilWireSign(
    t: params.t,
    n: params.n,
    ceremonySeed: shares.first.ceremonySeedBytes(),
    activePartyIdsZeroBased: active,
    message: message,
    executablePath: mithrilBridgePath,
  );

  if (!MlDsaThresholdVerifier.verify(
    scheme: params.scheme,
    publicKey: publicKey.bytes,
    message: message,
    signature: wire.signature,
    context: context,
  )) {
    throw InvalidPartialSignature('Mithril wire_sign produced invalid signature');
  }

  final wireMessages = mlDsaMessagesFromWireSignJson(
    params: params,
    ceremonyId: shares.first.ceremonyId,
    sessionId: wire.sessionId,
    wireJson: wire.wireJson,
  );

  return (
    signature: wire.signature,
    sessionId: wire.sessionId,
    wireMessages: wireMessages,
  );
}