doAuthentication static method

Future<(AuthKey, int)> doAuthentication(MTProtoPlainSender sender)

Performs the full authentication handshake and returns a tuple of (auth_key, time_offset).

The sender must be a connected MTProtoPlainSender that will be used to exchange the unencrypted DH messages with the server.

Throws SecurityError if any step of the handshake fails validation.

Implementation

static Future<(AuthKey, int)> doAuthentication(
  MTProtoPlainSender sender,
) async {
  final random = Random.secure();

  // Step 1: Request PQ
  final nonceBytes = Uint8List(16);
  for (var i = 0; i < 16; i++) {
    nonceBytes[i] = random.nextInt(256);
  }
  final nonce = _bytesToBigInt(nonceBytes, signed: true);

  _log.info('Starting authentication with nonce=${nonce.toRadixString(16)}');

  await sender.send(ReqPqMultiRequest(nonce: nonce));

  // The full implementation would proceed with:
  // 1. Parse ResPQ to get server_nonce, pq, and RSA fingerprints
  // 2. Factor pq into p and q using Factorization.factorize()
  // 3. Construct PQInnerData with nonce, server_nonce, new_nonce, pq, p, q
  // 4. RSA-encrypt PQInnerData using the server's public key fingerprint
  // 5. Send ReqDHParams with the encrypted inner data
  // 6. Decrypt the server's DH parameters using AES-IGE
  // 7. Validate g, dh_prime, g_a per MTProto security guidelines
  // 8. Generate random b, compute g_b = pow(g, b, dh_prime)
  // 9. Compute auth_key = pow(g_a, b, dh_prime)
  // 10. Send SetClientDHParams with encrypted g_b
  // 11. Verify DhGenOk and nonce hash

  // This requires full TL type registration and parsing support.
  // The framework is in place; complete implementation depends on
  // the TL layer code generation being wired up.
  throw UnimplementedError(
    'Full auth implementation requires TL type registration. '
    'The DH key exchange steps are documented above. '
    'Wire up the generated TL types to complete this.',
  );
}