cocos2dx使用xxtea加密资源

记录在cocos2dx下使用xxtea加密,以下都为ios版本操作

1.资源加密

quick有一个加密资源和脚本的解决方案，即使用xxtea加密并且可以进行打包，在pack_files文件夹下有一个pack_files.sh本人使用的mac，中windows中使用.bat

脚本命令的详细讲解，在这里只是使用了对资源进行加密，不进行打包。脚本命令如下

./pack_files.sh -i ./res -o ./resnew -ek key -es sign

1.资源读取

解密涉及到对cocos2dx引擎的一些改动，所以写了个ResourcesDecode类，cocos2dx本身含有xxtea类文件，把这2个类文件放入到项目cocos2d／cocos／platform下，在cocos2d.h文件夹中加入2个类的引用，在cocos2d／build目录下把2个类加入到ios的静态类库中，在AppDelegate.cpp场景切换之前加入

ResourcesDecode::getInstance()->setXXTEAKeyAndSign("key", "sign");

具体的方法会在 ResourcesDecode中介绍，会上传文件。

修改image.h中Image::initWithImageFile方法中做如下更改

Data data = ResourcesDecode::getInstance()->decodeData(path.c_str());

ios平台文件中的 apple／CCFileUtils中修改FileUtilsApple::getValueMapFromFile中做如下更改

Data data = ResourcesDecode::getInstance()->decodeData(fullPath.c_str());
ssize_t bufferSize = data.getSize();
unsigned char* pFileData = data.getBytes();
NSData *nsdata = [[[NSData alloc] initWithBytes:pFileData length:bufferSize] autorelease];

NSPropertyListFormat format;
NSString *error;
NSMutableDictionary *dict = (NSMutableDictionary *)[
                                                    NSPropertyListSerialization propertyListFromData:nsdata
                                                    mutabilityOption:NSPropertyListMutableContainersAndLeaves
                                                    format:&format
                                                    errorDescription:&error];
//over

读取json文件还需在FileUtils::getStringFromFile中做如下更改

Data data = ResourcesDecode::getInstance()->decodeData(path.c_str());

读取tilemap文件在SAXParser::parse下做如下更改

Data data = ResourcesDecode::getInstance()->decodeData(path.c_str());

上面的decodeData到底做了什么操作呢，其实就是读取到资源再对它解密操作

Data ResourcesDecode::decodeData(const char *fileName)
{
    Data ret;
    ssize_t dsize = 0;
    unsigned char* dresult;
    unsigned char* buffer = nullptr;
    size_t size = 0;
    size_t readsize;
    auto fileutils = FileUtils::getInstance();
    do
    {
        // Read the file from hardware
        std::string fullPath = fileutils->fullPathForFilename(fileName);
        FILE *fp = fopen(fullPath.c_str(), "rb");
        CC_BREAK_IF(!fp);
        fseek(fp,0,SEEK_END);
        size = ftell(fp);
        fseek(fp,0,SEEK_SET);

        buffer = (unsigned char*)malloc(sizeof(unsigned char) * size);
        readsize = fread(buffer, sizeof(unsigned char), size, fp);
        fclose(fp);

    } while (0);

    if (nullptr == buffer || 0 == readsize)
    {
        CCLOG("Get data from file %s failed", fileName);
    }
    if (_xxteaEnabled && strncmp((char*)buffer, _xxteaSign, _xxteaSignLen) == 0)
    {
        // decrypt XXTEA
        xxtea_long len = 0;
        dresult = xxtea_decrypt(buffer + _xxteaSignLen,
                                (xxtea_long)readsize - _xxteaSignLen,
                                (unsigned char*)_xxteaKey,
                                (xxtea_long)_xxteaKeyLen,
                                &len);
        dsize = len;
        ret.fastSet(dresult, dsize);
    }
    if (buffer) {
        free(buffer);
    }
    return ret;
}

可以参考 FileUtils ::getFileData中的处理。