Implementing Hash Chains with Crypto++

[Benjamin Oribe Mendieta]

I'm new to cryptography and to crypto++ in general, but I need to try a hash chain with the library, I got this code but I have an issue

    CryptoPP::Integer iRandomValue;

    CryptoPP::AutoSeededRandomPool prng;

    CryptoPP::SHA1 hash;

    std::string digest,tmp;

    std::ostringstream ossRandomValue;

    //RANDOM VALUE

    iRandomValue.Randomize(prng, bitsize);

    ossRandomValue << iRandomValue;

    tmp=ossRandomValue.str();

     std::cout<<"DEC VALUE :"<<std::dec<<iRandomValue<<std::endl;

    int i=0;

   while(i<2)

   {

        std::string sHash1;

        CryptoPP::HexEncoder hEncoder1(new CryptoPP::StringSink(sHash1));

       

        CryptoPP::StringSource(tmp, true, /*PumpAll*/

                                  new CryptoPP::Redirector(hEncoder1)

                                  );

        std::cout<<"ORIGINAL VALUE:"<<tmp<<":"<<std::endl;

        std::cout<<"HEX ORIGINAL VALUE:"<<sHash1<<std::endl;

        int x=0;

       

        if(i<=0)

            x=1;

        else

            x=0;

        hash.Update((const CryptoPP::byte*)sHash1.data(), sHash1.size());

        digest.resize(hash.DigestSize());

        hash.Final((CryptoPP::byte*)&digest[0]);

        CryptoPP::Integer result;

        result.Decode((CryptoPP::byte*)&digest[0],hash.DigestSize());

        std::ostringstream ossHashDecimal;

        ossHashDecimal << result;

        tmp=digest;

       

        std::cout<<"HASH VALUE DEC:"<<tmp<<std::endl;

       

        std::string sHash;

        CryptoPP::HexEncoder hEncoder(new CryptoPP::StringSink(sHash));

       

       

        CryptoPP::StringSource(digest, true, /*PumpAll*/

                                  new CryptoPP::Redirector(hEncoder)

                                  );

       

        std::cout<<"HASH VALUE:"<<sHash<<std::endl;

        i++;

    }

The first hash work pretty well, but when the result of the first hash is sent to create a new diggest the printed result doesn't match with another calculated hash, I tried online apliying two hashes to the same values, but don't get the same value as with these code.

Also, if anyone know if I need something to make faster the continuous hashing I'll be most thankful

I hope someone an solve my issue.