HashVerificationFilter和“消息散列或MAC无效”异常

Question

在Crpto ++中，可以轻松使用管道来对输入进行哈希处理。

std::string out;
CryptoPP::SHA256 sha;
CryptoPP::StringSource ss(input,true,
                          new CryptoPP::HashFilter(sha,
                              new CryptoPP::HexEncoder(
                                  new CryptoPP::StringSink(out))));

现在为了验证给出消息x产生相同的哈希输出，我想使用HashVerificationFilter。我试过了，但它不起作用。有人知道正确的语法吗？

const int flags = CryptoPP::HashVerificationFilter::THROW_EXCEPTION | CryptoPP::HashVerificationFilter::HASH_AT_END;
CryptoPP::SHA256 sha;
try
{
    CryptoPP::StringSource ss(input + out, true,
                              new CryptoPP::HashVerificationFilter(sha, NULL , flags));
}
catch(const CryptoPP::Exception& e)
{
    std::cerr << e.what() << std::endl;
    exit(1);
}

我得到了输出：

HashVerificationFilter: message hash or MAC not valid

Answer 1

std::string out;
SHA256 sha;
StringSource ss(input,true,
    new HashFilter(sha,
        new HexEncoder(
            new StringSink(out)
)));

你HexEncode你的哈希。在将其传递给过滤器之前，您需要对其进行解码：

StringSource ss(input + out, true,
    new HashVerificationFilter(sha, NULL , flags)
);

或者，删除编码过滤器：

std::string out;
SHA256 sha;
StringSource ss(input,true,
    new HashFilter(sha,
        new StringSink(out)
));