decryptData method

String decryptData(String ciphertext)

Decrypt data after reading.

Expects base64-encoded encrypted data with IV/nonce prepended.

Implementation

String decryptData(String ciphertext) {
  if (!config.enabled) return ciphertext;

  try {
    String decrypted;

    switch (config.algorithm) {
      case EncryptionAlgorithm.aes256GCM:
        decrypted = _decryptAesGcm(ciphertext);
        break;

      case EncryptionAlgorithm.aes256CBC:
        decrypted = _decryptAesCbc(ciphertext);
        break;

      case EncryptionAlgorithm.chacha20Poly1305:
        decrypted = _decryptChaCha20(ciphertext);
        break;
    }

    // Decompress if enabled
    if (config.compressBeforeEncryption) {
      final compressed = base64.decode(decrypted);
      final decompressed = gzip.decode(compressed);
      return utf8.decode(decompressed);
    }

    return decrypted;
  } catch (e) {
    throw EncryptionException('Decryption failed: $e');
  }
}