decryptStream abstract method

Stream<Uint8List> decryptStream(Stream<List<int>> data, List<int> iv)

Decrypt data with this AesCbcSecretKey using AES in Cipher Block Chaining mode, as specified in NIST SP800-38A.

To decrypt data the same initalization vector iv as was used for encryption must be specified. The iv must always be 16 bytes. See encryptBytes for further discussion of the initialization vector.

The encrypted data is always assumed to be padded in PKCS#7 mode, as described in RFC 2315 Section 10.3 step 2. This padding is stripped from the decrypted return value. The encryptBytes and encryptStream methods always apply this padding.

Example

import 'dart:io' show File;
import 'dart:convert' show utf8;
import 'dart:typed_data' show Uint8List;
import 'package:async/async.dart' show collectBytes;
import 'package:webcrypto/webcrypto.dart';

// Generate a new random AES-CBC secret key for AES-256.
final k = await AesCbcSecretKey.generate(256);

// Use a unique IV for each message.
final iv = Uint8List(16);
fillRandomBytes(iv);

// Encrypt a message from file and write to file
final inputFile = File('message.txt');
final encryptedFile = File('encrypted-message.binary');
final c = await k.encryptStream(
  inputFile.openRead(),
  iv,
).pipe(encryptedFile.openWrite());

// Decrypt message (requires the same iv)
final decryptedBytes = await collectBytes(k.decryptStream(
  encryptedFile.openRead(),
  iv, // same iv as used for encryption
));
// decryptedBytes should be equal to contents of inputFile
assert(utf8.decode(decryptedBytes) == inputFile.readAsStringSync());

Implementation

Stream<Uint8List> decryptStream(Stream<List<int>> data, List<int> iv);