SecretBox class

Output of encrypting bytes with a Cipher.

This class holds:

• nonce ("initialization vector", "IV", "salt")
• cipherText
• mac (message authentication code)

Concatenating fields

You can use concatenation and SecretBox.fromConcatenation to concatenate the fields into a single byte array:

import 'package:cryptography/cryptography.dart';

void main() async {
  final aesGcm = AesGcm.with256bits();
  final secretKey = await aesGcm.newSecretKey();
  final secretBox = await aesGcm.encrypt(
    [1,2,3],
    secretKey: secretKey,
  );

  // Returns nonce + cipherText + mac
  final bytes = secretBox.concatenation();
  print('Encrypted: $bytes');

  // Splits the bytes into nonce, ciphertext, and MAC.
  final newSecretBox = SecretBox.fromConcatenation(
    bytes,
    nonceLength: aesGcm.nonceLength,
    macLength: aesGcm.macAlgorithm.macLength,
    copy: false, // Don't copy the bytes unless necessary.
  );

  final clearText = await aesGcm.decrypt(
    newSecretBox,
    secretKey: secretKey,
  );
  print('Decrypted: $clearText');
}