AzDG可逆加密演算法 For Dart

Google 2011 年時所推出的語言，據說是要取代現有的Javascript，先前已有稍為看了一下，
因為沒有專案在使用這門語言，所以就沒有進一步的了解據聞公司明年的合作伙伴採用Dart來作為專案的主要撰寫語言，
所以再度把AzDG拿來練手，和google 另一門語言 Go 一樣還滿易學的。

import 'package:crypto/crypto.dart' show MD5, CryptoUtils;
import 'package:utf/utf.dart';

class AzDG {
    String _cipher = 'Private key';
    List< int > _cipherHash;
    AzDG({String cipher}) {
        if (cipher != null) {
            _cipher = cipher;
        }
        var md5 = new MD5();
        md5.add(this._cipher.codeUnits);
        _cipherHash = CryptoUtils.bytesToHex(md5.close()).codeUnits;
    }

    List < int > _cipherEncode(List < int > inputData) {
        var outData = new List < int > (inputData.length);
        var loopCount = inputData.length;
        for (var i = 0; i & lt; loopCount; i++) {
            outData[i] = inputData[i] ^ _cipherHash[i % 32];
        }
        return outData;
    }

    String Decrypt(String sourceText) {
        var decodeSourceText = _cipherEncode(CryptoUtils.base64StringToBytes(sourceText));
        var size = (decodeSourceText.length~ / 2).toInt();
        var outData = new List < int > (size);
        for (int j = 0; j < size; ++j) {
            outData[j] = (decodeSourceText[(j * 2)] ^ decodeSourceText[(j * 2) + 1]);
        }
        return decodeUtf8(outData);
    }

    String Crypt(String sourceText) {
        var now = new DateTime.now();
        var md5 = new MD5();
        md5.add(now.toString().codeUnits);
        var noise = CryptoUtils.bytesToHex(md5.close()).codeUnits;
        var inputData = encodeUtf8(sourceText);
        var outData = new List < int > (inputData.length * 2);
        for (var j = 0; j < inputData.length; j++) {
            outData[(j * 2)] = noise[j % 32];
            outData[(j * 2) + 1] = inputData[j] ^ noise[j % 32];
        }
        return CryptoUtils.bytesToBase64(_cipherEncode(outData));
    }
}