auth method

Future<String> auth(UdpAddress? remoteConnectionPoint)

Implementation

Future<String> auth(UdpAddress? remoteConnectionPoint) async {
  if (authProcessing) {
    return "auth processing ...";
  }

  try {
    authProcessing = true;
    var getNonceResult = await regularCall(
        remoteConnectionPoint, "/xchg-get-nonce", Uint8List(0), Uint8List(0));
    if (getNonceResult.isError()) {
      authProcessing = false;
      return "get nonce error:" + getNonceResult.error;
    }
    if (getNonceResult.data.length != 16) {
      authProcessing = false;
      return "nonce != 16";
    }

    if (remotePublicKey == null) {
      authProcessing = false;
      return "remotePublicKey == null";
    }

    var authDataBS = utf8.encode(authData);

    var localPublicKeyBS = encodePublicKeyToPKIX(keyPair.publicKey);

    // Prepare auth frame
    Uint8List authFrameSecret = Uint8List(16 + authDataBS.length);
    copyBytes(authFrameSecret, 0, getNonceResult.data);
    copyBytes(authFrameSecret, 16, Uint8List.fromList(authDataBS));
    // Encrypt auth frame
    Uint8List encryptedAuthFrame =
        await rsaEncrypt(remotePublicKey!, authFrameSecret);

    Uint8List authFrame =
        Uint8List(4 + localPublicKeyBS.length + encryptedAuthFrame.length);
    authFrame.buffer.asUint32List(0)[0] =
        localPublicKeyBS.buffer.lengthInBytes;
    copyBytes(authFrame, 4, localPublicKeyBS);
    copyBytes(authFrame, 4 + localPublicKeyBS.length, encryptedAuthFrame);

    CallResult authResult = await regularCall(
        remoteConnectionPoint, "/xchg-auth", authFrame, Uint8List(0));
    if (authResult.isError()) {
      authProcessing = false;
      return "auth error-:" + authResult.error;
    }

    Uint8List authResultDecrypted =
        await rsaDecrypt(keyPair.privateKey, authResult.data);

    if (authResultDecrypted.length != 8 + 32) {
      authProcessing = false;
      return "authResultDecrypted.length != 8 + 32";
    }

    sessionId = authResultDecrypted.buffer.asInt64List(0)[0];
    aesKey = authResultDecrypted.sublist(8);
  } catch (ex) {
    print("******************** auth Exception ee: $ex");
    authProcessing = false;
  }
  authProcessing = false;
  return "";
}