verify method

@override FutureOr<bool> verify(String jws, { String? did, Map<String, dynamic>? jwk, dynamic data, })

Verifies a (detached) JWS

Implementation

@override
FutureOr<bool> verify(String jws,
    {String? did, Map<String, dynamic>? jwk, dynamic data}) {
  var splitted = jws.split('.');
  if (splitted.length != 3) throw Exception('Malformed JWS');
  var signature = _getSignatureFromJws(jws);

  String payload;
  if (splitted[1] != '') {
    payload = splitted[1];
  } else if (data != null) {
    String signable = '';
    if (data is String) {
      signable = data;
    } else if (data is Map<String, dynamic>) {
      signable = jsonEncode(data);
    } else {
      throw Exception('Unexpected Datatype ${data.runtimeType} for toSign');
    }
    payload = removePaddingFromBase64(base64UrlEncode(utf8.encode(signable)));
  } else {
    throw Exception('No payload given');
  }

  var signingInput = '${splitted[0]}.$payload';
  var hashToSign = sha256.convert(ascii.encode(signingInput)).bytes;
  var pubKey = web3_crypto.ecRecover(hashToSign as Uint8List, signature);

  if (did != null) {
    return EthereumAddress.fromPublicKey(pubKey).hexEip55 ==
        did.split(':').last;
  } else if (jwk != null) {
    // TODO: Check if it works
    return EthereumAddress.fromPublicKey(pubKey).hexEip55 ==
        EthereumAddress.fromPublicKey(Uint8List.fromList(
                base64Decode(addPaddingToBase64(jwk['x']))))
            .hexEip55;
  } else {
    throw Exception('Either did or jwk must be given');
  }
}