CODEWITHSUNDEEP
c++boosthashsha1
werk
werk

Reputation: 342

runtime comparison of boost SHA1 hashing with md5sum/sha1sum

I used Boost to compute SHA1 hash, and then compared the rum time with Linux command md5sum and sha1sum. The file size is 28G. The md5sum and sha1sum are both version 8.4.

This is how I used Boost to compute SHA1:

void Sha1_Key(const std::string& inputfilename_, uint32_t* inputfile_sha1)
{
    std::string sha1_key_string;
    uint32_t local_sha1[5];

    for (uint32_t i = 0; i < 5; ++i)
    {
        inputfile_sha1[i] = local_sha1[i] = 0;
    }

    std::ifstream ifs(inputfilename_,std::ios::binary);

    boost::uuids::detail::sha1 sha1;
    std::stringstream sha1_key;
    char buf[128*1024];

    clock_t begin = clock();
    while(ifs.good()) {
      ifs.read(buf,sizeof(buf));
      sha1.process_bytes(buf,ifs.gcount());
    }

    ifs.close();
    sha1.get_digest(local_sha1);
    for(std::size_t i=0; i<sizeof(local_sha1)/sizeof(local_sha1[0]); ++i) {
      sha1_key<<std::hex<<local_sha1[i];
      inputfile_sha1[i] = local_sha1[i];
    }
    sha1_key_string = sha1_key.str();
    clock_t end = clock();
    std::cout << "run time for Boost SHA1: " << double(end - begin)/CLOCKS_PER_SEC << " sec"; 
}

This is the run time comparison:

The complexity of sha1sum is higher than md5sum, so sha1sum takes 50% more time. But the Boost SHA1 method run time is twice compared with the Linux sha1sum. Why?

Is there anything I can improve my code? Or any suggestion to other hash method to use?

Upvotes: 0

Views: 1047

Answers (1)

sehe
sehe

Reputation: 393134

boost::uuids::detail::sha1 sha1;

See that? ::detail::

That right there tells you you are abusing an undocumented implementation detail, that wasn't intended for your use.

That SHA implementation underpins UUID generation and wasn't designed to be fast for digesting large sequential streams.

That's all.

Use a proper sha1 implementation (libcrypto, cryptoc++ etc)

Upvotes: 4

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