Unity 打包 AssetBundle加密

zifa2003293 · 发表于 2021-7-16 12:35

AssetStudio解包工具（gitHub上可下载）：
链接：https://pan.baidu.com/s/1eZpjQaqOJHnGrP9H9PZeRQ
提取码：mbjq

方案一
在AssetBundle头部加入部分字节
[MenuItem("AssetBundle/Build Encrypt OffSet")] static void BuildEncryptOffSet() {       var exportPath = Application.streamingAssetsPath;       if (Directory.Exists(exportPath))       {          Directory.CreateDirectory(exportPath);       }       var manifest = BuildPipeline.BuildAssetBundles(exportPath,          BuildAssetBundleOptions.ChunkBasedCompression,          EditorUserBuildSettings.activeBuildTarget);       foreach (var abPath in manifest.GetAllAssetBundles())       {          string filepath = $"{Application.streamingAssetsPath}/{abPath}";          // 偏移值可调，或者动态设置都可以          uint offset = 96;          if ( offset > 0)          {             byte[] filedata = File.ReadAllBytes(filepath);             int filelen = ((int)offset + filedata.Length);             byte[] buffer = new byte[filelen];                               for (int slen = 0; slen < offset; slen++)             {                   buffer[slen] = 1;             }             for (int slen = 0; slen < filedata.Length; slen++)             {                   buffer[slen + offset] = filedata[slen];             }             FileStream fs = File.OpenWrite(filepath);             fs.Write(buffer, 0, filelen);             fs.Close();          }       } }
同步加载解密
protected AssetBundle _bundle;protected void AssetBundleUnCryptoSync(string assetBundlePatchFile)  {          uint offSet = 96;          _bundle = AssetBundle.LoadFromFile(assetBundlePatchFile, 0,offSet);  }
异步加载解密
protected IEnumerator AssetBundleUnCrypto(string assetBundlePatchFile)  {          uint offSet = 96;          AssetBundleCreateRequest request = AssetBundle.LoadFromFileAsync(assetBundlePatchFile, 0,offSet);          yield return request;          _bundle = request.assetBundle;  }
方案二
全字节加密
[MenuItem("AssetBundle/Build Encrypt")] static void BuildEncrypt() {       var exportPath = Application.streamingAssetsPath;       if (!Directory.Exists(exportPath))          Directory.CreateDirectory(exportPath);       var manifest = BuildPipeline.BuildAssetBundles(exportPath, BuildAssetBundleOptions.ChunkBasedCompression, EditorUserBuildSettings.activeBuildTarget);       foreach (var name in manifest.GetAllAssetBundles())       {          var uniqueSalt = Encoding.UTF8.GetBytes(name);          var data = File.ReadAllBytes($"{Application.streamingAssetsPath}/{name}");          using (var baseStream = new FileStream($"{Application.streamingAssetsPath}/{name}", FileMode.OpenOrCreate))          {             var cryptor = new SeekableAesStream(baseStream, "password", uniqueSalt);             cryptor.Write(data, 0, data.Length);          }       } }using System;using System.Collections;using System.Collections.Generic;using System.IO;using System.Security.Cryptography;using UnityEngine;public class SeekableAesStream : Stream{ private Stream baseStream; private AesManaged aes; private ICryptoTransform encryptor; public bool autoDisposeBaseStream { get; set; } = true; /// <param name="salt">//** WARNING **: MUST be unique for each stream otherwise there is NO security</param> public SeekableAesStream(Stream baseStream, string password, byte[] salt) {       this.baseStream = baseStream;       using (var key = new PasswordDeriveBytes(password, salt))       {          aes = new AesManaged();          aes.KeySize = 128;          aes.Mode = CipherMode.ECB;          aes.Padding = PaddingMode.None;          aes.Key = key.GetBytes(aes.KeySize / 8);          aes.IV = new byte[16]; //zero buffer is adequate since we have to use new salt for each stream          encryptor = aes.CreateEncryptor(aes.Key, aes.IV);       } } private void cipher(byte[] buffer, int offset, int count, long streamPos) {       //find block number       var blockSizeInByte = aes.BlockSize / 8;       var blockNumber = (streamPos / blockSizeInByte) + 1;       var keyPos = streamPos % blockSizeInByte;       //buffer       var outBuffer = new byte[blockSizeInByte];       var nonce = new byte[blockSizeInByte];       var init = false;       for (int i = offset; i < count; i++)       {          //encrypt the nonce to form next xor buffer (unique key)          if (!init || (keyPos % blockSizeInByte) == 0)          {             BitConverter.GetBytes(blockNumber).CopyTo(nonce, 0);             encryptor.TransformBlock(nonce, 0, nonce.Length, outBuffer, 0);             if (init) keyPos = 0;             init = true;             blockNumber++;          }          buffer ^= outBuffer[keyPos]; //simple XOR with generated unique key          keyPos++;       } } public override bool CanRead { get { return baseStream.CanRead; } } public override bool CanSeek { get { return baseStream.CanSeek; } } public override bool CanWrite { get { return baseStream.CanWrite; } } public override long Length { get { return baseStream.Length; } } public override long Position { get { return baseStream.Position; } set { baseStream.Position = value; } } public override void Flush() { baseStream.Flush(); } public override void SetLength(long value) { baseStream.SetLength(value); } public override long Seek(long offset, SeekOrigin origin) { return baseStream.Seek(offset, origin); } public override int Read(byte[] buffer, int offset, int count) {       var streamPos = Position;       var ret = baseStream.Read(buffer, offset, count);       cipher(buffer, offset, count, streamPos);       return ret; } public override void Write(byte[] buffer, int offset, int count) {       cipher(buffer, offset, count, Position);       baseStream.Write(buffer, offset, count); } protected override void Dispose(bool disposing) {       if (disposing)       {          encryptor?.Dispose();          aes?.Dispose();          if (autoDisposeBaseStream)             baseStream?.Dispose();       }       base.Dispose(disposing); }}
同步加载解密
      protected void AssetBundleUnCryptoSync(string assetBundlePatchFile)       {#if UNITY_EDITOR                      FileStream fileStream;          fileStream = new FileStream(assetBundlePatchFile, FileMode.Open);          var uniqueSalt1 = Encoding.UTF8.GetBytes(bundleName); // 打包时设置的salt名          // Stream暗号化解除          var uncryptor1 = new SeekableAesStream(fileStream, "password", uniqueSalt1);          _bundle = AssetBundle.LoadFromStream(uncryptor1);#else          var www = UnityWebRequest.Get(assetBundlePatchFile);          www.SendWebRequest();          // 阻塞，实现同步效果          while(!www.isDone){             System.Threading.Thread.Sleep (1/30);          }          if (!(www.isHttpError || www.isNetworkError))          {             var dataStream = new MemoryStream();             dataStream.Write(www.downloadHandler.data, 0, www.downloadHandler.data.Length);             var uniqueSalt = Encoding.UTF8.GetBytes(bundleName); // 打包时设置的salt名             // Stream暗号化解除             var uncryptor = new SeekableAesStream(dataStream, AssetBundlePathResolver.BundlePassword, uniqueSalt);             _bundle = AssetBundle.LoadFromStream(uncryptor);          }          else          {             LuaInterface.Debugger.Log(string.Format("{1}:[{0}]",www.error,"www.error"));          }                      www.Dispose();          www = null;#endif                      this.Complete();       }
方案一，性能几乎无消耗
方案二，性能消耗比较大
如果对加密要求不是很高，推荐使用方案一。

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