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Portable C++ Hashing Library

This is a mirror of my library hosted at

In a nutshell:

  • computes CRC32, MD5, SHA1 and SHA256 (most common member of the SHA2 functions), Keccak and its SHA3 sibling
  • optional HMAC (keyed-hash message authentication code)
  • no external dependencies, small code size
  • can work chunk-wise (for example when reading streams block-by-block)
  • portable: supports Windows and Linux, tested on Little Endian and Big Endian CPUs
  • roughly as fast as Linux core hashing functions
  • open source, zlib license

You can find code examples, benchmarks and much more on my website

How to use

This example computes SHA256 hashes but the API is more or less identical for all hash algorithms:

// SHA2 test program
#include "sha256.h"
#include <iostream> // for std::cout only, not needed for hashing library

int main(int, char**)
  // create a new hashing object
  SHA256 sha256;

  // hashing an std::string
  std::cout << sha256("Hello World") << std::endl;
  // => a591a6d40bf420404a011733cfb7b190d62c65bf0bcda32b57b277d9ad9f146e

  // hashing a buffer of bytes
  const char* buffer = "How are you";
  std::cout << sha256(buffer, 11) << std::endl;
  // => 9c7d5b046878838da72e40ceb3179580958df544b240869b80d0275cc07209cc

  // or in a streaming fashion (re-use "How are you")
  SHA256 sha256stream;
  const char* url = ""; // 25 bytes
  int step = 5;
  for (int i = 0; i < 25; i += step)
    sha256stream.add(url + i, step); // add five bytes at a time
  std::cout << sha256stream.getHash() << std::endl;
  // => 82aa771f1183c52f973c798c9243a1c73833ea40961c73e55e12430ec77b69f6

  return 0;