hash functions

There is code kicking around the internet for the sha256 and md5 hashing algorithms. With thanks to the original developers, I've modified the code to improve the interface somewhat, and also to be more standards compliant.

testing

Requires gcc-7. Edit the CC variable in the Makefile to change compiler. Works with recent versions of clang as well.

make test
./test

example

#include <iostream>

#include "md5.hpp"
#include "sha256.hpp"

static const std::string data("Data to hash.");

template<typename T> std::string hash_value()
{
   T hash;
   hash.append(data);
   hash.append("You can continue to append more data.");
   return hash.hexdigest();
}

int main(int, char**)
{
   std::cout << "\nhash-functions example.\n\n";

   std::cout << "   MD5 digest:    " << hash_value<MD5>() << "\n";
   std::cout << "   Sha256 digest: " << hash_value<Sha256>() << "\n";
   std::cout << std::endl;

   return EXIT_SUCCESS;
}

Output:

hash-functions example.

   MD5 digest:    3ce726ece4dfa2dc4206a92fcda92c8b
   Sha256 digest: fba7d1847458e31310a20c05d943377d6c45232bba304336167ba3c6e108ea96