verify method

bool verify(Map<String, dynamic> publicKeyJwk)

Implementation

bool verify(Map<String, dynamic> publicKeyJwk) {
  var crv = publicKeyJwk['crv'];
  if (crv == null) throw Exception('Jwk without crv parameter');
  bool valid = true;
  for (var s in signatures) {
    var alg = s.protected!['alg'];
    if (alg == null) {
      throw Exception('alg property must be present');
    } else if (alg == JwsSignatureAlgorithm.edDsa.value) {
      if (crv != 'Ed25519') throw Exception('wrong curve for algorithm $alg');
      var publicKey =
          ed.PublicKey(base64Decode(addPaddingToBase64(publicKeyJwk['x'])));
      var encodedHeader = removePaddingFromBase64(
          base64UrlEncode(utf8.encode(jsonEncode(s.protected))));
      valid = ed.verify(
          publicKey,
          ascii.encode(
              '$encodedHeader.${_base64Payload ?? removePaddingFromBase64(base64UrlEncode(utf8.encode(payload.toString())))}'),
          base64Decode(addPaddingToBase64(s.signature)));
    } else if (alg == JwsSignatureAlgorithm.es256.value) {
      if (crv != 'P-256') throw Exception('wrong curve for algorithm $alg');
      var pubKey = EcPublicKey(
          xCoordinate: bytesToUnsignedInt(
              base64Decode(addPaddingToBase64(publicKeyJwk['x']))),
          yCoordinate: bytesToUnsignedInt(
              base64Decode(addPaddingToBase64(publicKeyJwk['y']))),
          curve: curves.p256);
      var verifier = pubKey.createVerifier(algorithms.signing.ecdsa.sha256);
      var encodedHeader = removePaddingFromBase64(
          base64UrlEncode(utf8.encode(jsonEncode(s.protected))));
      valid = verifier.verify(
          ascii.encode(
              '$encodedHeader.${_base64Payload ?? removePaddingFromBase64(base64UrlEncode(utf8.encode(payload.toString())))}'),
          Signature(base64Decode(addPaddingToBase64(s.signature))));
    } else if (alg == JwsSignatureAlgorithm.es256k.value) {
      if (crv != 'secp256k1') {
        throw Exception('wrong curve for algorithm $alg');
      }
      var pubKey = EcPublicKey(
          xCoordinate: bytesToUnsignedInt(
              base64Decode(addPaddingToBase64(publicKeyJwk['x']))),
          yCoordinate: bytesToUnsignedInt(
              base64Decode(addPaddingToBase64(publicKeyJwk['y']))),
          curve: curves.p256k);
      var verifier = pubKey.createVerifier(algorithms.signing.ecdsa.sha256);
      var encodedHeader = removePaddingFromBase64(
          base64UrlEncode(utf8.encode(jsonEncode(s.protected))));
      valid = verifier.verify(
          ascii.encode(
              '$encodedHeader.${_base64Payload ?? removePaddingFromBase64(base64UrlEncode(utf8.encode(payload.toString())))}'),
          Signature(base64Decode(addPaddingToBase64(s.signature))));
    } else {
      throw UnimplementedError('Other signing algorithms are not supported');
    }
  }
  return valid;
}