Wednesday, November 5, 2008

MD5 algorithm C++ implementation

/* md5.c - MD5 Message-Digest Algorithm
 * Copyright (C) 1995,1996,1998,1999,2001,2002,
 *               2003  Free Software Foundation, Inc.
 *
 * This file is part of Libgcrypt.
 *
 * Libgcrypt is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * Libgcrypt is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
 *
 * According to the definition of MD5 in RFC 1321 from April 1992.
 * NOTE: This is *not* the same file as the one from glibc.
 * Written by Ulrich Drepper , 1995.
 * heavily modified for GnuPG by Werner Koch
 */

#ifndef _MD5_H_
#define _MD5_H_

#include
#include
#include
#include "CryptoBase.h"

/* Test values:
 * ""                  D4 1D 8C D9 8F 00 B2 04  E9 80 09 98 EC F8 42 7E
 * "a"                 0C C1 75 B9 C0 F1 B6 A8  31 C3 99 E2 69 77 26 61
 * "abc                90 01 50 98 3C D2 4F B0  D6 96 3F 7D 28 E1 7F 72
 * "message digest"    F9 6B 69 7D 7C B7 93 8D  52 5A 2F 31 AA F1 61 D0
 */

namespace Crypto
{
//#define  WORDS_BIGENDIAN

class md5
{
protected:
    u32 _A, _B, _C, _D;    // chaining variables
    u32  _nblocks;      // max digest size is limited to 64 * 4G
    int  _count;
    u8 _buf[64];

    const u32 rol (const u32 x, const unsigned int n) const  { return ( ((x) << (n)) | ((x) >> (32-(n))) ); }

    void copy_u32 (u32& dest, const u32 src)
    {
#ifdef WORDS_BIGENDIAN
        dest =   ( ((src&0x000000FF) << 24) | ((src&0x0000FF00) << 8) |
                 ((src&0x00FF0000) >> 8)  | ((src&0xFF000000) >> 24) );
#else
        dest = src;
#endif
    }
  
    /* These are the four functions used in the four steps of the MD5 algorithm
       and defined in the RFC 1321.  The first function is a little bit optimized
       (as found in Colin Plumbs public domain implementation).  */
    /* #define FF(b, c, d) ((b & c) | (~b & d)) */
    const u32 FF(const u32 b, const u32 c, const u32 d) const {    return (d ^ (b & (c ^ d))); }
    const u32 FG(const u32 b, const u32 c, const u32 d) const { return  FF (d, b, c);    }
  
    const u32 FH(const u32 b, const u32 c, const u32 d) const { return (b ^ c ^ d);        }
    const u32 FI(const u32 b, const u32 c, const u32 d) const { return (c ^ (b | ~d));    }

    void round1(u32& a, const u32 b, const u32 c, const u32 d, const u32 Xk, const u32 s, const u32 Ti) {
        a += FF (b, c, d) + Xk + Ti;
        a = rol(a, s);
        a += b;
    }

    void round2(u32& a, const u32 b, const u32 c, const u32 d, const u32 Xk, const u32 s, const u32 Ti) {
        a += FG(b, c, d) + Xk + Ti;
        a = rol(a, s);
        a += b;
    }

    void round3(u32& a, const u32 b, const u32 c, const u32 d, const u32 Xk, const u32 s, const u32 Ti) {
        a += FH(b, c, d) + Xk + Ti;  
        a = rol(a, s);
        a += b;
    }

    void round4(u32& a, const u32 b, const u32 c, const u32 d, const u32 Xk, const u32 s, const u32 Ti) {
        a += FI(b, c, d) + Xk + Ti;  
        a = rol(a, s);
        a += b;
    }

    /****************
     * transform 64 bytes
     */
    void transform (const void* const data )
    {
      
        u32 A = _A;
        u32 B = _B;
        u32 C = _C;
        u32 D = _D;

#ifdef WORDS_BIGENDIAN
        u32 correct_words[16];
        const u32 * const src = reinterpret_cast(data);
        for(size_t n=0; n<16; n++) {
            copy_u32(correct_words[n], src[n]);
        }
#else
        const u32* const correct_words = reinterpret_cast(data);
#endif
  
        // Before we start, one word about the strange constants.
        // They are defined in RFC 1321 as
        // T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
      
        round1 (A, B, C, D, correct_words[0],  7,  0xd76aa478);
        round1 (D, A, B, C, correct_words[1],  12, 0xe8c7b756);
        round1 (C, D, A, B, correct_words[2],  17, 0x242070db);
        round1 (B, C, D, A, correct_words[3],  22, 0xc1bdceee);
        round1 (A, B, C, D, correct_words[4],  7,  0xf57c0faf);
        round1 (D, A, B, C, correct_words[5],  12, 0x4787c62a);
        round1 (C, D, A, B, correct_words[6],  17, 0xa8304613);
        round1 (B, C, D, A, correct_words[7],  22, 0xfd469501);
        round1 (A, B, C, D, correct_words[8],  7, 0x698098d8);
        round1 (D, A, B, C, correct_words[9],  12, 0x8b44f7af);
        round1 (C, D, A, B, correct_words[10], 17, 0xffff5bb1);
        round1 (B, C, D, A, correct_words[11], 22, 0x895cd7be);
        round1 (A, B, C, D, correct_words[12], 7, 0x6b901122);
        round1 (D, A, B, C, correct_words[13], 12, 0xfd987193);
        round1 (C, D, A, B, correct_words[14], 17, 0xa679438e);
        round1 (B, C, D, A, correct_words[15], 22, 0x49b40821);
  
        round2 (A, B, C, D, correct_words[1],  5,  0xf61e2562);
        round2 (D, A, B, C, correct_words[6],  9,  0xc040b340);
        round2 (C, D, A, B, correct_words[11], 14, 0x265e5a51);
        round2 (B, C, D, A, correct_words[0],  20, 0xe9b6c7aa);
        round2 (A, B, C, D, correct_words[5],  5,  0xd62f105d);
        round2 (D, A, B, C, correct_words[10], 9,  0x02441453);
        round2 (C, D, A, B, correct_words[15], 14, 0xd8a1e681);
        round2 (B, C, D, A, correct_words[4],  20, 0xe7d3fbc8);
        round2 (A, B, C, D, correct_words[9],  5,  0x21e1cde6);
        round2 (D, A, B, C, correct_words[14], 9,  0xc33707d6);
        round2 (C, D, A, B, correct_words[3],  14, 0xf4d50d87);
        round2 (B, C, D, A, correct_words[8],  20, 0x455a14ed);
        round2 (A, B, C, D, correct_words[13], 5,  0xa9e3e905);
        round2 (D, A, B, C, correct_words[2],  9,  0xfcefa3f8);
        round2 (C, D, A, B, correct_words[7],  14, 0x676f02d9);
        round2 (B, C, D, A, correct_words[12], 20, 0x8d2a4c8a);
  
        round3 (A, B, C, D, correct_words[ 5],  4, 0xfffa3942);
        round3 (D, A, B, C, correct_words[ 8], 11, 0x8771f681);
        round3 (C, D, A, B, correct_words[11], 16, 0x6d9d6122);
        round3 (B, C, D, A, correct_words[14], 23, 0xfde5380c);
        round3 (A, B, C, D, correct_words[ 1],  4, 0xa4beea44);
        round3 (D, A, B, C, correct_words[ 4], 11, 0x4bdecfa9);
        round3 (C, D, A, B, correct_words[ 7], 16, 0xf6bb4b60);
        round3 (B, C, D, A, correct_words[10], 23, 0xbebfbc70);
        round3 (A, B, C, D, correct_words[13],  4, 0x289b7ec6);
        round3 (D, A, B, C, correct_words[ 0], 11, 0xeaa127fa);
        round3 (C, D, A, B, correct_words[ 3], 16, 0xd4ef3085);
        round3 (B, C, D, A, correct_words[ 6], 23, 0x04881d05);
        round3 (A, B, C, D, correct_words[ 9],  4, 0xd9d4d039);
        round3 (D, A, B, C, correct_words[12], 11, 0xe6db99e5);
        round3 (C, D, A, B, correct_words[15], 16, 0x1fa27cf8);
        round3 (B, C, D, A, correct_words[ 2], 23, 0xc4ac5665);
  
        round4 (A, B, C, D, correct_words[ 0],  6, 0xf4292244);
        round4 (D, A, B, C, correct_words[ 7], 10, 0x432aff97);
        round4 (C, D, A, B, correct_words[14], 15, 0xab9423a7);
        round4 (B, C, D, A, correct_words[ 5], 21, 0xfc93a039);
        round4 (A, B, C, D, correct_words[12],  6, 0x655b59c3);
        round4 (D, A, B, C, correct_words[ 3], 10, 0x8f0ccc92);
        round4 (C, D, A, B, correct_words[10], 15, 0xffeff47d);
        round4 (B, C, D, A, correct_words[ 1], 21, 0x85845dd1);
        round4 (A, B, C, D, correct_words[ 8],  6, 0x6fa87e4f);
        round4 (D, A, B, C, correct_words[15], 10, 0xfe2ce6e0);
        round4 (C, D, A, B, correct_words[ 6], 15, 0xa3014314);
        round4 (B, C, D, A, correct_words[13], 21, 0x4e0811a1);
        round4 (A, B, C, D, correct_words[ 4],  6, 0xf7537e82);
        round4 (D, A, B, C, correct_words[11], 10, 0xbd3af235);
        round4 (C, D, A, B, correct_words[ 2], 15, 0x2ad7d2bb);
        round4 (B, C, D, A, correct_words[ 9], 21, 0xeb86d391);
  
        // Put checksum in context given as argument.
        _A += A;
        _B += B;
        _C += C;
        _D += D;
    }
  
public:
    void start()
    {
        _A = 0x67452301;
        _B = 0xefcdab89;
        _C = 0x98badcfe;
        _D = 0x10325476;
  
        _count = 0;
        _nblocks = 0;
    }

    void update(const void* const inbuf_arg , size_t inlen)
    {
        const unsigned char* inbuf = (const unsigned char *)inbuf_arg;
        if( !inbuf  || !inlen ) {
            return;
        }

        assert(_count < 64);
        if( _count ) {
            for( ; inlen && _count < 64; inlen-- ) {
                _buf[_count++] = *inbuf++;
            }
            if(_count == 64) {
                transform( _buf);
                _count = 0;
                _nblocks++;
            }
        }

        while( inlen >= 64 ) {
            assert(_count == 0);
            transform(inbuf );
            _count = 0;
            _nblocks++;
            inlen -= 64;
            inbuf += 64;
        }
        for( ; inlen && _count < 64; inlen-- ) {
            _buf[_count++] = *inbuf++;
        }
    }

    u8 *end()
    {
        u32 t, len_h, len_l;

        // multiply by 64, than 8  to make a bit count
        len_l = _nblocks << (6 + 3);
        len_h = _nblocks >> (32 - 6 - 3);
  
        // add the count
        t = len_l;
        if( (len_l += (_count << 3)) < t ) {
            len_h++;
        }

        if( _count < 56 )  {// enough room
            _buf[_count++] = 0x80; /* pad */
            while(_count < 56 )
                _buf[_count++] = 0;  /* pad */
        } else  { // need one extra block
            _buf[_count++] = 0x80; /* pad character */
            while( _count < 64 )
                _buf[_count++] = 0;
            transform( _buf); // _count = 0; _nblocks++;
            memset(_buf, 0, 56 ); // fill next block with zeroes
        }

        // append the 64 bit count
        _buf[56] = len_l       ;
        _buf[57] = len_l >>  8;
        _buf[58] = len_l >> 16;
        _buf[59] = len_l >> 24;
        _buf[60] = len_h       ;
        _buf[61] = len_h >>  8;
        _buf[62] = len_h >> 16;
        _buf[63] = len_h >> 24;
        transform( _buf );
      
        u32* md5 = reinterpret_cast(_buf);
        copy_u32(md5[0], _A);
        copy_u32(md5[1], _B);
        copy_u32(md5[2], _C);
        copy_u32(md5[3], _D);
      
        return _buf;
    }

    static u32 digest_size() { return 4; }

    static std::string get_str(const u8* const md5_buf, const Base::StrType str_type = Base::StrHex)
    {
        std::string str, sub_str;
        if(md5_buf) {
            Base::to_str(str, reinterpret_cast(md5_buf), digest_size(), str_type);
        }
      
        return str;
    }
  
    // handy tools
    u8 *digest(std::ifstream& is)
    {
        if(is.good()) {
            start();
            const int buff_size = 64 * 16; // 1K
            char buffer[buff_size];
            std::streamsize length;
            while (!is.eof()) {
                is.read(buffer, buff_size);
                length = is.gcount();
                if (length > 0) {
                    update(buffer, length);
                }
            }
            return end();
        }
        return NULL;
    }
};

} // namespace Crypto

#endif //#ifndef _MD5_H_

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