79 lines
1.9 KiB
Dart
79 lines
1.9 KiB
Dart
// Copyright 2019-2023 Hugo Pointcheval
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//
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file or at
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// https://opensource.org/licenses/MIT.
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// ignore_for_file: implementation_imports
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import 'dart:typed_data';
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import 'package:pointycastle/export.dart';
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import 'package:pointycastle/src/platform_check/platform_check.dart';
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class AesGcm {
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FortunaRandom? _secureRandom;
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Uint8List encrypt(Uint8List data, Uint8List key) {
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final iv = generateRandomBytes(12);
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final gcm = GCMBlockCipher(AESEngine())
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..init(
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true,
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AEADParameters(
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KeyParameter(key),
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16 * 8,
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iv!,
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Uint8List(0),
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),
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); // true=encrypt
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final cipherText = gcm.process(data);
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return Uint8List.fromList(
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iv + cipherText,
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);
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}
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Uint8List decrypt(Uint8List cipherText, Uint8List key) {
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final iv = Uint8List.fromList(cipherText.sublist(0, 12));
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final cipherTextWithoutIv = Uint8List.fromList(
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cipherText.sublist(12),
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);
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final gcm = GCMBlockCipher(AESEngine())
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..init(
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false,
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AEADParameters(
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KeyParameter(key),
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16 * 8,
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iv,
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Uint8List(0),
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),
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); // false=decrypt
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// Decrypt the cipherText block-by-block
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final paddedPlainText = gcm.process(cipherTextWithoutIv);
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return paddedPlainText;
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}
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/// Generate random bytes to use as the Initialization Vector (IV).
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Uint8List? generateRandomBytes(int numBytes) {
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if (_secureRandom == null) {
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// First invocation: create _secureRandom and seed it
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_secureRandom = FortunaRandom();
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_secureRandom!.seed(
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KeyParameter(Platform.instance.platformEntropySource().getBytes(32)),
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);
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}
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// Use it to generate the random bytes
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final iv = _secureRandom!.nextBytes(numBytes);
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return iv;
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}
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}
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