C++ md5 function

MD5 is no longer considered cryptographically safe for digital signatures, however, because the md5 hash function is still useful for other purposes, code is provided below.

SHA2 (usually sha256) is recommended for new applications for digital signatures and collision resistance instead of md5 or sha1. For password hashing, even sha2 and sha3 functions are insufficient on their own. A good password hashing algorithm needs to cryptographically safe, use a unique random salt for each hash (which can be safely stored with the hash), and have an adjustable work factor. Blowfish is therefore considered the best choice for password hashing.

main.cpp

#include <iostream>
#include "md5.h"
 
using std::cout; using std::endl;
 
int main(int argc, char *argv[])
{
    cout << "md5 of 'grape': " << md5("grape") << endl;
    return 0;
}

compile and run in linux:

g++ main.cpp md5.cpp -o md5_sample && ./md5_sample

output:

md5 of 'grape': b781cbb29054db12f88f08c6e161c199

md5.h

/* MD5
 converted to C++ class by Frank Thilo (thilo@unix-ag.org)
 for bzflag (http://www.bzflag.org)
 
   based on:
 
   md5.h and md5.c
   reference implementation of RFC 1321
 
   Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
rights reserved.
 
License to copy and use this software is granted provided that it
is identified as the "RSA Data Security, Inc. MD5 Message-Digest
Algorithm" in all material mentioning or referencing this software
or this function.
 
License is also granted to make and use derivative works provided
that such works are identified as "derived from the RSA Data
Security, Inc. MD5 Message-Digest Algorithm" in all material
mentioning or referencing the derived work.
 
RSA Data Security, Inc. makes no representations concerning either
the merchantability of this software or the suitability of this
software for any particular purpose. It is provided "as is"
without express or implied warranty of any kind.
 
These notices must be retained in any copies of any part of this
documentation and/or software.
 
*/
 
#ifndef BZF_MD5_H
#define BZF_MD5_H
 
#include <cstring>
#include <iostream>
 
 
// a small class for calculating MD5 hashes of strings or byte arrays
// it is not meant to be fast or secure
//
// usage: 1) feed it blocks of uchars with update()
//      2) finalize()
//      3) get hexdigest() string
//      or
//      MD5(std::string).hexdigest()
//
// assumes that char is 8 bit and int is 32 bit
class MD5
{
public:
  typedef unsigned int size_type; // must be 32bit
 
  MD5();
  MD5(const std::string& text);
  void update(const unsigned char *buf, size_type length);
  void update(const char *buf, size_type length);
  MD5& finalize();
  std::string hexdigest() const;
  friend std::ostream& operator<<(std::ostream&, MD5 md5);
 
private:
  void init();
  typedef unsigned char uint1; //  8bit
  typedef unsigned int uint4;  // 32bit
  enum {blocksize = 64}; // VC6 won't eat a const static int here
 
  void transform(const uint1 block[blocksize]);
  static void decode(uint4 output[], const uint1 input[], size_type len);
  static void encode(uint1 output[], const uint4 input[], size_type len);
 
  bool finalized;
  uint1 buffer[blocksize]; // bytes that didn't fit in last 64 byte chunk
  uint4 count[2];   // 64bit counter for number of bits (lo, hi)
  uint4 state[4];   // digest so far
  uint1 digest[16]; // the result
 
  // low level logic operations
  static inline uint4 F(uint4 x, uint4 y, uint4 z);
  static inline uint4 G(uint4 x, uint4 y, uint4 z);
  static inline uint4 H(uint4 x, uint4 y, uint4 z);
  static inline uint4 I(uint4 x, uint4 y, uint4 z);
  static inline uint4 rotate_left(uint4 x, int n);
  static inline void FF(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  static inline void GG(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  static inline void HH(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  static inline void II(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
};
 
std::string md5(const std::string str);
 
#endif

md5.cpp

/* MD5
 converted to C++ class by Frank Thilo (thilo@unix-ag.org)
 for bzflag (http://www.bzflag.org)
 
   based on:
 
   md5.h and md5.c
   reference implemantion of RFC 1321
 
   Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
rights reserved.
 
License to copy and use this software is granted provided that it
is identified as the "RSA Data Security, Inc. MD5 Message-Digest
Algorithm" in all material mentioning or referencing this software
or this function.
 
License is also granted to make and use derivative works provided
that such works are identified as "derived from the RSA Data
Security, Inc. MD5 Message-Digest Algorithm" in all material
mentioning or referencing the derived work.
 
RSA Data Security, Inc. makes no representations concerning either
the merchantability of this software or the suitability of this
software for any particular purpose. It is provided "as is"
without express or implied warranty of any kind.
 
These notices must be retained in any copies of any part of this
documentation and/or software.
 
*/
 
/* interface header */
#include "md5.h"
 
/* system implementation headers */
#include <cstdio>
 
 
// Constants for MD5Transform routine.
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21
 
///////////////////////////////////////////////
 
// F, G, H and I are basic MD5 functions.
inline MD5::uint4 MD5::F(uint4 x, uint4 y, uint4 z) {
  return x&y | ~x&z;
}
 
inline MD5::uint4 MD5::G(uint4 x, uint4 y, uint4 z) {
  return x&z | y&~z;
}
 
inline MD5::uint4 MD5::H(uint4 x, uint4 y, uint4 z) {
  return x^y^z;
}
 
inline MD5::uint4 MD5::I(uint4 x, uint4 y, uint4 z) {
  return y ^ (x | ~z);
}
 
// rotate_left rotates x left n bits.
inline MD5::uint4 MD5::rotate_left(uint4 x, int n) {
  return (x << n) | (x >> (32-n));
}
 
// FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
// Rotation is separate from addition to prevent recomputation.
inline void MD5::FF(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {
  a = rotate_left(a+ F(b,c,d) + x + ac, s) + b;
}
 
inline void MD5::GG(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {
  a = rotate_left(a + G(b,c,d) + x + ac, s) + b;
}
 
inline void MD5::HH(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {
  a = rotate_left(a + H(b,c,d) + x + ac, s) + b;
}
 
inline void MD5::II(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {
  a = rotate_left(a + I(b,c,d) + x + ac, s) + b;
}
 
//////////////////////////////////////////////
 
// default ctor, just initailize
MD5::MD5()
{
  init();
}
 
//////////////////////////////////////////////
 
// nifty shortcut ctor, compute MD5 for string and finalize it right away
MD5::MD5(const std::string &text)
{
  init();
  update(text.c_str(), text.length());
  finalize();
}
 
//////////////////////////////
 
void MD5::init()
{
  finalized=false;
 
  count[0] = 0;
  count[1] = 0;
 
  // load magic initialization constants.
  state[0] = 0x67452301;
  state[1] = 0xefcdab89;
  state[2] = 0x98badcfe;
  state[3] = 0x10325476;
}
 
//////////////////////////////
 
// decodes input (unsigned char) into output (uint4). Assumes len is a multiple of 4.
void MD5::decode(uint4 output[], const uint1 input[], size_type len)
{
  for (unsigned int i = 0, j = 0; j < len; i++, j += 4)
    output[i] = ((uint4)input[j]) | (((uint4)input[j+1]) << 8) |
      (((uint4)input[j+2]) << 16) | (((uint4)input[j+3]) << 24);
}
 
//////////////////////////////
 
// encodes input (uint4) into output (unsigned char). Assumes len is
// a multiple of 4.
void MD5::encode(uint1 output[], const uint4 input[], size_type len)
{
  for (size_type i = 0, j = 0; j < len; i++, j += 4) {
    output[j] = input[i] & 0xff;
    output[j+1] = (input[i] >> 8) & 0xff;
    output[j+2] = (input[i] >> 16) & 0xff;
    output[j+3] = (input[i] >> 24) & 0xff;
  }
}
 
//////////////////////////////
 
// apply MD5 algo on a block
void MD5::transform(const uint1 block[blocksize])
{
  uint4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];
  decode (x, block, blocksize);
 
  /* Round 1 */
  FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /* 1 */
  FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /* 2 */
  FF (c, d, a, b, x[ 2], S13, 0x242070db); /* 3 */
  FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /* 4 */
  FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /* 5 */
  FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /* 6 */
  FF (c, d, a, b, x[ 6], S13, 0xa8304613); /* 7 */
  FF (b, c, d, a, x[ 7], S14, 0xfd469501); /* 8 */
  FF (a, b, c, d, x[ 8], S11, 0x698098d8); /* 9 */
  FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /* 10 */
  FF (c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
  FF (b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
  FF (a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
  FF (d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
  FF (c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
  FF (b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
 
  /* Round 2 */
  GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /* 17 */
  GG (d, a, b, c, x[ 6], S22, 0xc040b340); /* 18 */
  GG (c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
  GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /* 20 */
  GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /* 21 */
  GG (d, a, b, c, x[10], S22,  0x2441453); /* 22 */
  GG (c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
  GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /* 24 */
  GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /* 25 */
  GG (d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
  GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /* 27 */
  GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /* 28 */
  GG (a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
  GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /* 30 */
  GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /* 31 */
  GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
 
  /* Round 3 */
  HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /* 33 */
  HH (d, a, b, c, x[ 8], S32, 0x8771f681); /* 34 */
  HH (c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
  HH (b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
  HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /* 37 */
  HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /* 38 */
  HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /* 39 */
  HH (b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
  HH (a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
  HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /* 42 */
  HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /* 43 */
  HH (b, c, d, a, x[ 6], S34,  0x4881d05); /* 44 */
  HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /* 45 */
  HH (d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
  HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
  HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /* 48 */
 
  /* Round 4 */
  II (a, b, c, d, x[ 0], S41, 0xf4292244); /* 49 */
  II (d, a, b, c, x[ 7], S42, 0x432aff97); /* 50 */
  II (c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
  II (b, c, d, a, x[ 5], S44, 0xfc93a039); /* 52 */
  II (a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
  II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /* 54 */
  II (c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
  II (b, c, d, a, x[ 1], S44, 0x85845dd1); /* 56 */
  II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /* 57 */
  II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
  II (c, d, a, b, x[ 6], S43, 0xa3014314); /* 59 */
  II (b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
  II (a, b, c, d, x[ 4], S41, 0xf7537e82); /* 61 */
  II (d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
  II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /* 63 */
  II (b, c, d, a, x[ 9], S44, 0xeb86d391); /* 64 */
 
  state[0] += a;
  state[1] += b;
  state[2] += c;
  state[3] += d;
 
  // Zeroize sensitive information.
  memset(x, 0, sizeof x);
}
 
//////////////////////////////
 
// MD5 block update operation. Continues an MD5 message-digest
// operation, processing another message block
void MD5::update(const unsigned char input[], size_type length)
{
  // compute number of bytes mod 64
  size_type index = count[0] / 8 % blocksize;
 
  // Update number of bits
  if ((count[0] += (length << 3)) < (length << 3))
    count[1]++;
  count[1] += (length >> 29);
 
  // number of bytes we need to fill in buffer
  size_type firstpart = 64 - index;
 
  size_type i;
 
  // transform as many times as possible.
  if (length >= firstpart)
  {
    // fill buffer first, transform
    memcpy(&buffer[index], input, firstpart);
    transform(buffer);
 
    // transform chunks of blocksize (64 bytes)
    for (i = firstpart; i + blocksize <= length; i += blocksize)
      transform(&input[i]);
 
    index = 0;
  }
  else
    i = 0;
 
  // buffer remaining input
  memcpy(&buffer[index], &input[i], length-i);
}
 
//////////////////////////////
 
// for convenience provide a verson with signed char
void MD5::update(const char input[], size_type length)
{
  update((const unsigned char*)input, length);
}
 
//////////////////////////////
 
// MD5 finalization. Ends an MD5 message-digest operation, writing the
// the message digest and zeroizing the context.
MD5& MD5::finalize()
{
  static unsigned char padding[64] = {
    0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
  };
 
  if (!finalized) {
    // Save number of bits
    unsigned char bits[8];
    encode(bits, count, 8);
 
    // pad out to 56 mod 64.
    size_type index = count[0] / 8 % 64;
    size_type padLen = (index < 56) ? (56 - index) : (120 - index);
    update(padding, padLen);
 
    // Append length (before padding)
    update(bits, 8);
 
    // Store state in digest
    encode(digest, state, 16);
 
    // Zeroize sensitive information.
    memset(buffer, 0, sizeof buffer);
    memset(count, 0, sizeof count);
 
    finalized=true;
  }
 
  return *this;
}
 
//////////////////////////////
 
// return hex representation of digest as string
std::string MD5::hexdigest() const
{
  if (!finalized)
    return "";
 
  char buf[33];
  for (int i=0; i<16; i++)
    sprintf(buf+i*2, "%02x", digest[i]);
  buf[32]=0;
 
  return std::string(buf);
}
 
//////////////////////////////
 
std::ostream& operator<<(std::ostream& out, MD5 md5)
{
  return out << md5.hexdigest();
}
 
//////////////////////////////
 
std::string md5(const std::string str)
{
    MD5 md5 = MD5(str);
 
    return md5.hexdigest();
}

code snippets are licensed under Creative Commons CC-By-SA 3.0 (unless otherwise specified)

Max on 2009-09-16 21:01:00

This works perfectly. Thanks alot for this. It's also about 10 (!!!) times faster than windows built in wincrypt.h libraries.

Anon on 2009-10-13 20:34:08

I would like to thank you from this code.
Afaik, i got it work 100% on c++ builder 2007.
So far this is the only code i found effective for my problem, which even google werent able to sort out.
Thank you!

Mike on 2009-10-28 19:23:54

Great work! Thanks for posting it. It worked from C++ builder without any modifications.

String hashResult=md5(stringToHash.c_str()).c_str();

tesla on 2010-01-10 04:04:00

Thanks for this one, great work!

MASTER on 2011-01-16 08:05:45

Thanks buddy, I liked your code very much, To those who are getting errors add both files (md5.h and md5.cpp) into your project then compile problems arisis when you only try to compile the main.cpp file without adding above mentioned two files in your project.

Thanks again for this wonderful code.

Tommy on 2011-01-30 01:25:57

Thank you!! This code took less than 2 minutes to throw into my project and start using. Exactly what I needed...it is amazing.

Fedot on 2011-02-11 14:20:50

Beautifull!

Antuan on 2011-07-01 08:38:52

GGGGGrreat !
thank u very much : D

bahaba on 2011-08-10 20:30:05

Terrific! Only needed to add an extern for md5() and add an include for string.h (for memset, memcpy)... using MINGW g++ compiler on Windows. My test returned the same hash as PHP md5().