AB包简单加密，offset加密

Scene：1个GameObject，1个UI

Assets：1个图片，1个Prefab，1个材质

• AssetStudio验证

• 游戏加载验证

​ 2.1 获取原AB包的HashCode

​ 2.2 提取HashCode作为参数计算偏移量offset：

for (int i = 0,iMax = hashchar.Length; i < 3; ++i)
{
	offset += (int)hashchar[i];
}

​ 2.3 从原数据中选取offset长度的数据作为假数据头RandomHead（这样不同的子包，每次加密，他们前offset位的数据都是随机的）

private static byte[] GetRandomHead(byte[] sourceData,int headLength)
    {
        byte[] head = new byte[headLength];
        int startIdx = 0;
        int randomParam = UnityEngine.Random.Range(0, sourceData.Length - headLength);
        for (int i = randomParam, iMax = randomParam + headLength; i < iMax; ++i,++startIdx)
        {
            head[startIdx] = sourceData[i];
        }
        return head;
    }

​ 2.4 把 RandomHead 写到原数据前，实现简单的offset加密

private static void SetOffset(ref byte[] buffer,byte[] head,byte[] sourceData)
    {
        for (int i = 0,iMax = sourceData.Length + head.Length; i < iMax; ++i)
        {
            if (i 
 
 
AssetStudio验证
 
[黑Saber姐姐不见了]
 
 
 
 
游戏加载验证
 
private Sprite LoadImg()
    {
        Sprite icon = null;
        string outputPath = Application.dataPath + "/BuildAssetBundle/Window/";
        AssetBundle.UnloadAllAssetBundles(true);
        AssetBundle ab = AssetBundle.LoadFromFile(outputPath + bundleName);
        icon = ab.LoadAsset(spriteName);
        return icon;
    }
 
[黑Saber姐姐不见了] +1
 
 
 
3.解密 
根据hash算出每个子包的offset，然后略过他们
 
private static void DelateOffset(ref byte[] buffer,int offset,byte[] sourceData)
    {
        for (int i = 0,iMax = sourceData.Length; i < iMax; ++i)
        {
            if (i < offset)
            {
                continue;
            }
            
            buffer[i - offset] = sourceData[i];
        }
    }
 
AssetStudio验证
 
 
 
游戏加载验证
 
private Sprite LoadImg_decryption()
    {
        Sprite icon = null;
        string outputPath = Application.dataPath + "/BuildAssetBundle/Window/";
        AssetBundle.UnloadAllAssetBundles(true);
        AssetBundle ab = AssetBundle.LoadFromFile(outputPath + bundleName, 0, (ulong)GetOffset());
        icon = ab.LoadAsset(spriteName);
        return icon;
    }