'消息散列或MAC无效'异常解密后 [英] 'message hash or MAC not valid' exception after decryption

问题描述

我试图制作一个程序，使用crypto ++库加密文件（.jpg和.avi）。我的目标是制作一个使用AES-256成功加密视频文件的程序。

I'm trying to make a program that encrypts files (.jpg and .avi) using the crypto++ libraries. My aim is to make a program that successfully encrypts video files using AES-256.

我从这里，他们成功运行（意味着库已正确设置）。但是，以下简单代码会生成异常

I did text examples of AES encryption from here and they ran successfully (meaning that the library is setup correctly). However, the following simple code produces the exception

HashVerificationFilter: message hash or MAC not valid

代码：

AutoSeededRandomPool prng;

SecByteBlock key(AES::DEFAULT_KEYLENGTH);
prng.GenerateBlock(key, key.size());

SecByteBlock iv(AES::BLOCKSIZE);
prng.GenerateBlock(iv, iv.size());

string ofilename = "testimage.png";
string efilename;
string rfilename = "testimagerecovered.png";

try
{

    GCM< AES >::Encryption e;
    e.SetKeyWithIV(key, key.size(), iv, iv.size());

    ifstream ofile(ofilename.c_str(), ios::binary);
    ofile.seekg(0, ios_base::beg);

    FileSource fs1(ofilename.c_str(), true,
            new AuthenticatedEncryptionFilter(e,
                    new StringSink(efilename)));

    GCM< AES >::Decryption d2;
    d2.SetKeyWithIV(key, key.size(), iv, sizeof(iv));

    StringSource fs2(efilename, true,
            new AuthenticatedDecryptionFilter( d2,
                    new FileSink (rfilename.c_str()),
                    AuthenticatedDecryptionFilter::THROW_EXCEPTION));
}
catch(const Exception &e)
{
    cerr << e.what() << endl;
    exit(1);
}

return 0;

我怀疑我没有正确实现AES算法。但是，我无法找到最近两天的解决方案。我在Ubuntu 14.04上使用Eclipse Luna。

I suspect I am not implementing the AES algorithm correctly. However, I am unable to find a solution for the last two days. I'm using Eclipse Luna on Ubuntu 14.04.

我已经经历了以下的答案

PS I have gone through the following answers

如何将图像读取到字符串以进行加密Crypto ++

如何循环Blowfish Crypto ++

推荐答案

请使用 iv.size $ c>而不是 sizeof（iv），当你尝试设置 d2.SetKeyWithIV ，就像你做到 e.SetKeyWithIV 。
因为在此程序中， iv.size（）的值为16，但 sizeof（iv）是24.然后它会工作。

Please use iv.size() rather than sizeof(iv) when you try to set d2.SetKeyWithIV, just like what you have done to e.SetKeyWithIV. Because in this program, the value of iv.size() is 16, but sizeof(iv) is 24. Then it will work.

GCM< AES >::Decryption d2;
d2.SetKeyWithIV(key, key.size(), iv, iv.size()); //here was a misuse of sizeof(iv)

StringSource fs2(efilename, true,
        new AuthenticatedDecryptionFilter( d2,
                new FileSink (rfilename.c_str()),
                AuthenticatedDecryptionFilter::THROW_EXCEPTION));

通过我的测试的代码如上。

The code which has passed my test is as above.

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