aeadEncrypt function

Uint8List? aeadEncrypt(Uint8List key, Uint8List iv, int packetNumber, Uint8List plaintext, Uint8List aad,)

Performs AES-GCM encryption following the QUIC nonce construction.

Implementation

Uint8List? aeadEncrypt(
  Uint8List key,
  Uint8List iv,
  int packetNumber,
  Uint8List plaintext,
  Uint8List aad,
) {
  try {
    // 1. Determine Key length
    if (key.length != 16 && key.length != 32) {
      throw Exception(
        "Unsupported key length: ${key.length}. Must be 16 or 32 bytes.",
      );
    }

    // 2. Compute Nonce
    final nonce = computeNonce(iv, packetNumber);

    // 3. Perform Encryption (This needs a proper AEAD encrypt primitive)
    // Since the JS function returns the combined ciphertext+tag, we need a helper
    // that produces both the ciphertext and the 16-byte tag.

    // This part is highly dependent on the Dart crypto library used.
    // For simplicity, we assume an encrypt primitive that returns a combined result.
    // NOTE: For GCM, the primitive must return (ciphertext + tag).

    // --- Placeholder for combined encryption primitive ---
    Uint8List combinedCiphertextTag(
      Uint8List key,
      Uint8List nonce,
      Uint8List plaintext,
      Uint8List aad,
    ) {
      final encrypted = encrypt(
        encryptionKey: key,
        message: plaintext,
        nonce: nonce,
        aead: aad,
      );
      // return Uint8List.fromList([...aad, ...encrypted]);
      return encrypted;
    }
    // --- End Placeholder ---

    final combined = combinedCiphertextTag(key, nonce, plaintext, aad);
    return combined;
  } catch (e, st) {
    print("AEAD Encryption failed: $e");
    print(st);
    return null;
  }
}