src/md5.c

   1 /*Copyright (c) Brian B.
   2
   3   This library is free software; you can redistribute it and/or
   4   modify it under the terms of the GNU Lesser General Public
   5   License as published by the Free Software Foundation; either
   6   version 3 of the License, or (at your option) any later version.
   7   See the file LICENSE included with this distribution for more
   8   information.
   9 */
  10 #include "md5.h"
  11
  12 #define A 0x67452301
  13 #define B 0xefcdab89
  14 #define C 0x98badcfe
  15 #define D 0x10325476
  16
  17 static uint32_t S[] = {7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
  18                        5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20, 5,  9, 14, 20,
  19                        4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
  20                        6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21};
  21
  22 static uint32_t K[] = {0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
  23                        0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
  24                        0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
  25                        0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
  26                        0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
  27                        0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
  28                        0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
  29                        0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
  30                        0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
  31                        0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
  32                        0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
  33                        0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
  34                        0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
  35                        0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
  36                        0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
  37                        0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391};
  38
  39 #define F(X, Y, Z) ((X & Y) | (~X & Z))
  40 #define G(X, Y, Z) ((X & Z) | (Y & ~Z))
  41 #define H(X, Y, Z) (X ^ Y ^ Z)
  42 #define I(X, Y, Z) (Y ^ (X | ~Z))
  43
  44 static uint8_t PADDING[] = {0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  45                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  46                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  47                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  48                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  49                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  50                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  51                             0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
  52
  53 void md5_init(md5_t *ctx){
  54     ctx->size = (uint64_t)0;
  55
  56     ctx->buffer[0] = (uint32_t)A;
  57     ctx->buffer[1] = (uint32_t)B;
  58     ctx->buffer[2] = (uint32_t)C;
  59     ctx->buffer[3] = (uint32_t)D;
  60 }
  61
  62 uint32_t rotate_left(uint32_t x, uint32_t n){
  63     return (x << n) | (x >> (32 - n));
  64 }
  65
  66 static void md5_step(uint32_t *buffer, uint32_t *input){
  67     uint32_t AA = buffer[0];
  68     uint32_t BB = buffer[1];
  69     uint32_t CC = buffer[2];
  70     uint32_t DD = buffer[3];
  71
  72     uint32_t E;
  73
  74     unsigned int j;
  75
  76     for(unsigned int i = 0; i < 64; ++i){
  77         switch(i / 16){
  78             case 0:
  79                 E = F(BB, CC, DD);
  80                 j = i;
  81                 break;
  82             case 1:
  83                 E = G(BB, CC, DD);
  84                 j = ((i * 5) + 1) % 16;
  85                 break;
  86             case 2:
  87                 E = H(BB, CC, DD);
  88                 j = ((i * 3) + 5) % 16;
  89                 break;
  90             default:
  91                 E = I(BB, CC, DD);
  92                 j = (i * 7) % 16;
  93                 break;
  94         }
  95
  96         uint32_t temp = DD;
  97         DD = CC;
  98         CC = BB;
  99         BB = BB + rotate_left(AA + E + K[i] + input[j], S[i]);
 100         AA = temp;
 101     }
 102
 103     buffer[0] += AA;
 104     buffer[1] += BB;
 105     buffer[2] += CC;
 106     buffer[3] += DD;
 107 }
 108 void md5_update(md5_t *ctx, uint8_t *input_buffer, size_t input_len){
 109     uint32_t input[16];
 110     unsigned int offset = ctx->size % 64;
 111     ctx->size += (uint64_t)input_len;
 112
 113     for(unsigned int i = 0; i < input_len; ++i){
 114         ctx->input[offset++] = (uint8_t)*(input_buffer + i);
 115         if(offset % 64 == 0){
 116             for(unsigned int j = 0; j < 16; ++j){
 117                 input[j] = (uint32_t)(ctx->input[(j * 4) + 3]) << 24 |
 118                            (uint32_t)(ctx->input[(j * 4) + 2]) << 16 |
 119                            (uint32_t)(ctx->input[(j * 4) + 1]) <<  8 |
 120                            (uint32_t)(ctx->input[(j * 4)]);
 121             }
 122             md5_step(ctx->buffer, input);
 123             offset = 0;
 124         }
 125     }
 126 }
 127
 128 void md5_final(md5_t *ctx){
 129     uint32_t input[16];
 130     unsigned int offset = ctx->size % 64;
 131     unsigned int padding_length = offset < 56 ? 56 - offset : (56 + 64) - offset;
 132
 133     md5_update(ctx, PADDING, padding_length);
 134     ctx->size -= (uint64_t)padding_length;
 135
 136     for(unsigned int j = 0; j < 14; ++j){
 137         input[j] = (uint32_t)(ctx->input[(j * 4) + 3]) << 24 |
 138                    (uint32_t)(ctx->input[(j * 4) + 2]) << 16 |
 139                    (uint32_t)(ctx->input[(j * 4) + 1]) <<  8 |
 140                    (uint32_t)(ctx->input[(j * 4)]);
 141     }
 142     input[14] = (uint32_t)(ctx->size * 8);
 143     input[15] = (uint32_t)((ctx->size * 8) >> 32);
 144
 145     md5_step(ctx->buffer, input);
 146
 147     for(unsigned int i = 0; i < 4; ++i){
 148         ctx->digest[(i * 4) + 0] = (uint8_t)((ctx->buffer[i] & 0x000000FF));
 149         ctx->digest[(i * 4) + 1] = (uint8_t)((ctx->buffer[i] & 0x0000FF00) >>  8);
 150         ctx->digest[(i * 4) + 2] = (uint8_t)((ctx->buffer[i] & 0x00FF0000) >> 16);
 151         ctx->digest[(i * 4) + 3] = (uint8_t)((ctx->buffer[i] & 0xFF000000) >> 24);
 152     }
 153 }