????數(shù)據(jù)或文件加密是游戲中常見的需求偶垮，針對重要配置文件和敏感數(shù)據(jù)铡俐，加密存儲，運行時解密使用脯倚，對游戲的安全性是很有必要的。我們項目中對個別配置文件和Lua文件也做了加密處理，加解密算法則采用廣泛使用的XXTEA算法推正，下面簡單介紹一下恍涂。

????TEA(Tiny Encryption Algorithm)是一種小型的對稱加密解密算法,最初是由劍橋計算機實驗室的 David Wheeler 和 Roger Needham 在 1994 年設(shè)計的。它支持128位密碼,可以為 64 位的信息塊進行加密植榕，每次加密/解密8字節(jié)數(shù)據(jù)再沧，需要進行 64 輪迭代。該算法使用了一個神秘常數(shù)δ作為倍數(shù)尊残，來源于黃金比率炒瘸，以保證每一輪加密都不相同，在程序中為0x9E3779B9寝衫。TEA特點是速度快顷扩、效率高，實現(xiàn)也非常簡單慰毅。TEA后續(xù)發(fā)展出XTEA隘截、Block TEA和XXTEA等版本。其中XXTE算法安全事富，非臣祭快速，也適合大文件的加解密统台，所以被項目采用雕擂。

????XXTEA代碼很簡單，網(wǎng)上也有各種版本贱勃，下附一個C#版：

public class XXTEA
{
    #region Encrypt
    public static string Encrypt(string source, string key)
    {
        byte[] sourceByteArry = Encoding.UTF8.GetBytes(base64Encode(source));
        if (sourceByteArry.Length == 0)
        {
            return "";
        }

        byte[] keyByteArry = Encoding.UTF8.GetBytes(key);

        return Convert.ToBase64String(ToByteArray(Encrypt(ToUintArray(sourceByteArry, true), ToUintArray(keyByteArry, false)), false));
    }

    public static uint[] Encrypt(uint[] v, uint[] k)
    {
        int n = v.Length - 1;
        if (n < 1)
        {
            return v;
        }
        if (k.Length < 4)
        {
            uint[] Key = new uint[4];
            k.CopyTo(Key, 0);
            k = Key;
        }
        uint z = v[n], y = v[0], delta = 0x9E3779B9, sum = 0, e;
        int p, q = 6 + 52 / (n + 1);
        while (q-- > 0)
        {
            sum = unchecked(sum + delta);
            e = sum >> 2 & 3;
            for (p = 0; p < n; p++)
            {
                y = v[p + 1];
                z = unchecked(v[p] += (z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z));
            }
            y = v[0];
            z = unchecked(v[n] += (z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z));
        }
        return v;
    }

    private static string base64Encode(string data)
    {
        try
        {
            byte[] encData_byte = new byte[data.Length];
            encData_byte = Encoding.UTF8.GetBytes(data);
            string encodedData = Convert.ToBase64String(encData_byte);
            return encodedData;
        }
        catch (Exception e)
        {
            throw new Exception("Error in base64Encode" + e.Message);
        }
    }
    #endregion

    #region Decrypt
    public static string Decrypt(string source, string key)
    {
        if (source.Length == 0)
        {
            return "";
        }

        byte[] bytData = Convert.FromBase64String(source);
        byte[] bytKey = Encoding.UTF8.GetBytes(key);

        return base64Decode(Encoding.UTF8.GetString(ToByteArray(Decrypt(ToUintArray(bytData, false), ToUintArray(bytKey, false)), true)));
    }

    public static uint[] Decrypt(uint[] v, uint[] k)
    {
        int n = v.Length - 1;
        if (n < 1)
        {
            return v;
        }
        if (k.Length < 4)
        {
            uint[] Key = new uint[4];
            k.CopyTo(Key, 0);
            k = Key;
        }
        uint z = v[n], y = v[0], delta = 0x9E3779B9, sum, e;
        int p, q = 6 + 52 / (n + 1);
        sum = unchecked((uint)(q * delta));
        while (sum != 0)
        {
            e = sum >> 2 & 3;
            for (p = n; p > 0; p--)
            {
                z = v[p - 1];
                y = unchecked(v[p] -= (z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z));
            }
            z = v[n];
            y = unchecked(v[0] -= (z >> 5 ^ y << 2) + (y >> 3 ^ z << 4) ^ (sum ^ y) + (k[p & 3 ^ e] ^ z));
            sum = unchecked(sum - delta);
        }
        return v;
    }

    private static string base64Decode(string data)
    {
        try
        {
            byte[] todecode_byte = Convert.FromBase64String(data);
            return Encoding.UTF8.GetString(todecode_byte);
        }
        catch (Exception e)
        {
            throw new Exception("Error in base64Decode" + e.Message);
        }
    }
    #endregion

    private static uint[] ToUintArray(byte[] Data, bool IncludeLength)
    {
        int n = (((Data.Length & 3) == 0) ? (Data.Length >> 2) : ((Data.Length >> 2) + 1));
        uint[] Result;
        if (IncludeLength)
        {
            Result = new uint[n + 1];
            Result[n] = (uint)Data.Length;
        }
        else
        {
            Result = new uint[n];
        }
        n = Data.Length;
        for (int i = 0; i < n; i++)
        {
            Result[i >> 2] |= (uint)Data[i] << ((i & 3) << 3);
        }
        return Result;
    }

    private static byte[] ToByteArray(uint[] Data, bool IncludeLength)
    {
        int n;
        if (IncludeLength)
        {
            n = (int)Data[Data.Length - 1];
        }
        else
        {
            n = Data.Length << 2;
        }
        byte[] Result = new byte[n];
        for (int i = 0; i < n; i++)
        {
            Result[i] = (byte)(Data[i >> 2] >> ((i & 3) << 3));
        }
        return Result;
    }
}

使用方法直接調(diào)用加/解密函數(shù)即可：

    class Program
    {
        static void Main(string[] args)
        {
            string content = "content_Test";
            string password = "ABC123";
            string encryptString = XXTEA.Encrypt(content, password);
            string result = XXTEA.Decrypt(encryptString, password);
            Console.WriteLine(result);
        }
    }

result輸出 "content_Test"