108 lines
2.5 KiB
Dart
108 lines
2.5 KiB
Dart
import 'dart:convert';
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import 'dart:typed_data';
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import 'package:pointycastle/export.dart';
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class AesDecrypt {
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static const String _cn = 'i0.a';
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static const List<int> _obf = <int>[
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0xED,
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0x7A,
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0x7F,
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0x3F,
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0x9E,
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0x6E,
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0xE7,
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0xF9,
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0x06,
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0xA0,
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0xA8,
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0xE4,
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0x16,
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0xE5,
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0x69,
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0x70,
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];
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/// Java String.hashCode() 等价实现（32-bit signed）
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static int javaStringHashCode(String str) {
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int h = 0;
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for (int i = 0; i < str.length; i++) {
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h = _toSigned32(h * 31 + str.codeUnitAt(i));
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}
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return h;
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}
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static int _toSigned32(int value) {
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value &= 0xFFFFFFFF;
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if ((value & 0x80000000) != 0) {
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return value - 0x100000000;
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}
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return value;
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}
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static int _unsignedRightShift32(int value, int shift) {
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return (value & 0xFFFFFFFF) >> shift;
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}
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static Uint8List deriveKeyBytes16() {
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final int seed = _toSigned32(javaStringHashCode(_cn) ^ 0x5f3759df);
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final Uint8List keyBytes = Uint8List(16);
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for (int i = 0; i < 16; i++) {
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final int shift = (i & 3) * 8;
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final int shifted = _unsignedRightShift32(seed, shift);
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final int mask = (((shifted & 0xff) ^ ((i * 17 + 31) & 0xff)) & 0xff);
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keyBytes[i] = (_obf[i] ^ mask) & 0xff;
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}
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return keyBytes;
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}
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static Uint8List _aesEcbPkcs7(bool forEncryption, Uint8List input) {
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final key = deriveKeyBytes16();
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final cipher = PaddedBlockCipherImpl(
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PKCS7Padding(),
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ECBBlockCipher(AESEngine()),
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);
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cipher.init(
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forEncryption,
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PaddedBlockCipherParameters<CipherParameters, CipherParameters>(
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KeyParameter(key),
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null,
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),
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);
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return cipher.process(input);
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}
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/// 对应 JS / Java encrypt(String) -> Base64.NO_WRAP
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static String encrypt(String plainText) {
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try {
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final Uint8List input = Uint8List.fromList(utf8.encode(plainText));
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final Uint8List encrypted = _aesEcbPkcs7(true, input);
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return base64.encode(encrypted);
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} catch (_) {
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return '';
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}
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}
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/// 对应 JS / Java decrypt(String base64Encrypted) -> UTF-8
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static String? decrypt(String base64Encrypted) {
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try {
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final Uint8List encrypted = Uint8List.fromList(
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base64.decode(base64Encrypted),
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);
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final Uint8List decrypted = _aesEcbPkcs7(false, encrypted);
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final String text = utf8.decode(decrypted, allowMalformed: false);
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return text.isNotEmpty ? text : null;
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} catch (_) {
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return null;
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}
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}
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}
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