1/* md5.c - Functions to compute MD5 message digest of files or memory blocks
2   according to the definition of MD5 in RFC 1321 from April 1992.
3   Copyright (C) 1995 Software Foundation, Inc.
4
5   This program is free software; you can redistribute it and/or modify
6   it under the terms of the GNU General Public License as published by
7   the Free Software Foundation; either version 2, or (at your option)
8   any later version.
9
10   This program is distributed in the hope that it will be useful,
11   but WITHOUT ANY WARRANTY; without even the implied warranty of
12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13   GNU General Public License for more details.
14
15   You should have received a copy of the GNU General Public License
16   along with this program; if not, write to the Free Software
17   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
18
19/* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>.  */
20
21#ifdef HAVE_CONFIG_H
22# include <config.h>
23#endif
24
25#include <sys/types.h>
26
27#if STDC_HEADERS
28# include <stdlib.h>
29# include <string.h>
30#else
31# ifndef HAVE_MEMCPY
32#  define memcpy(d, s, n) bcopy ((s), (d), (n))
33# endif
34#endif
35
36#include "md5.h"
37
38#ifdef WORDS_BIGENDIAN
39# define SWAP(n)							\
40    (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
41#else
42# define SWAP(n) (n)
43#endif
44
45
46/* This array contains the bytes used to pad the buffer to the next
47   64-byte boundary.  (RFC 1321, 3.1: Step 1)  */
48static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ...  */ };
49
50
51/* Initialize structure containing state of computation.
52   (RFC 1321, 3.3: Step 3)  */
53void
54md5_init_ctx (ctx)
55     struct md5_ctx *ctx;
56{
57  ctx->A = 0x67452301;
58  ctx->B = 0xefcdab89;
59  ctx->C = 0x98badcfe;
60  ctx->D = 0x10325476;
61}
62
63/* Put result from CTX in first 16 bytes following RESBUF.  The result must
64   be in little endian byte order.  */
65void *
66md5_read_ctx (ctx, resbuf)
67     const struct md5_ctx *ctx;
68     void *resbuf;
69{
70  ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
71  ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
72  ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
73  ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
74
75  return resbuf;
76}
77
78/* Compute MD5 message digest for bytes read from STREAM.  The
79   resulting message digest number will be written into the 16 bytes
80   beginning at RESBLOCK.  */
81int
82md5_stream (stream, resblock)
83     FILE *stream;
84     void *resblock;
85{
86  /* Important: BLOCKSIZE must be a multiple of 64.  */
87#define BLOCKSIZE 4096
88  struct md5_ctx ctx;
89  md5_uint32 len[2];
90  char buffer[BLOCKSIZE + 72];
91  size_t pad, sum;
92
93  /* Initialize the computation context.  */
94  md5_init_ctx (&ctx);
95
96  len[0] = 0;
97  len[1] = 0;
98
99  /* Iterate over full file contents.  */
100  while (1)
101    {
102      /* We read the file in blocks of BLOCKSIZE bytes.  One call of the
103	 computation function processes the whole buffer so that with the
104	 next round of the loop another block can be read.  */
105      size_t n;
106      sum = 0;
107
108      /* Read block.  Take care for partial reads.  */
109      do
110	{
111	  n = fread (buffer, 1, BLOCKSIZE - sum, stream);
112
113	  sum += n;
114	}
115      while (sum < BLOCKSIZE && n != 0);
116      if (n == 0 && ferror (stream))
117        return 1;
118
119      /* RFC 1321 specifies the possible length of the file up to 2^64 bits.
120	 Here we only compute the number of bytes.  Do a double word
121         increment.  */
122      len[0] += sum;
123      if (len[0] < sum)
124	++len[1];
125
126      /* If end of file is reached, end the loop.  */
127      if (n == 0)
128	break;
129
130      /* Process buffer with BLOCKSIZE bytes.  Note that
131			BLOCKSIZE % 64 == 0
132       */
133      md5_process_block (buffer, BLOCKSIZE, &ctx);
134    }
135
136  /* We can copy 64 byte because the buffer is always big enough.  FILLBUF
137     contains the needed bits.  */
138  memcpy (&buffer[sum], fillbuf, 64);
139
140  /* Compute amount of padding bytes needed.  Alignment is done to
141		(N + PAD) % 64 == 56
142     There is always at least one byte padded.  I.e. even the alignment
143     is correctly aligned 64 padding bytes are added.  */
144  pad = sum & 63;
145  pad = pad >= 56 ? 64 + 56 - pad : 56 - pad;
146
147  /* Put the 64-bit file length in *bits* at the end of the buffer.  */
148  *(md5_uint32 *) &buffer[sum + pad] = SWAP (len[0] << 3);
149  *(md5_uint32 *) &buffer[sum + pad + 4] = SWAP ((len[1] << 3)
150						 | (len[0] >> 29));
151
152  /* Process last bytes.  */
153  md5_process_block (buffer, sum + pad + 8, &ctx);
154
155  /* Construct result in desired memory.  */
156  md5_read_ctx (&ctx, resblock);
157  return 0;
158}
159
160/* Compute MD5 message digest for LEN bytes beginning at BUFFER.  The
161   result is always in little endian byte order, so that a byte-wise
162   output yields to the wanted ASCII representation of the message
163   digest.  */
164void *
165md5_buffer (buffer, len, resblock)
166     const char *buffer;
167     size_t len;
168     void *resblock;
169{
170  struct md5_ctx ctx;
171  char restbuf[64 + 72];
172  size_t blocks = len & ~63;
173  size_t pad, rest;
174
175  /* Initialize the computation context.  */
176  md5_init_ctx (&ctx);
177
178  /* Process whole buffer but last len % 64 bytes.  */
179  md5_process_block (buffer, blocks, &ctx);
180
181  /* REST bytes are not processed yet.  */
182  rest = len - blocks;
183  /* Copy to own buffer.  */
184  memcpy (restbuf, &buffer[blocks], rest);
185  /* Append needed fill bytes at end of buffer.  We can copy 64 byte
186     because the buffer is always big enough.  */
187  memcpy (&restbuf[rest], fillbuf, 64);
188
189  /* PAD bytes are used for padding to correct alignment.  Note that
190     always at least one byte is padded.  */
191  pad = rest >= 56 ? 64 + 56 - rest : 56 - rest;
192
193  /* Put length of buffer in *bits* in last eight bytes.  */
194  *(md5_uint32 *) &restbuf[rest + pad] = (md5_uint32) SWAP (len << 3);
195  *(md5_uint32 *) &restbuf[rest + pad + 4] = (md5_uint32) SWAP (len >> 29);
196
197  /* Process last bytes.  */
198  md5_process_block (restbuf, rest + pad + 8, &ctx);
199
200  /* Put result in desired memory area.  */
201  return md5_read_ctx (&ctx, resblock);
202}
203
204
205/* These are the four functions used in the four steps of the MD5 algorithm
206   and defined in the RFC 1321.  The first function is a little bit optimized
207   (as found in Colin Plumbs public domain implementation).  */
208/* #define FF(b, c, d) ((b & c) | (~b & d)) */
209#define FF(b, c, d) (d ^ (b & (c ^ d)))
210#define FG(b, c, d) FF (d, b, c)
211#define FH(b, c, d) (b ^ c ^ d)
212#define FI(b, c, d) (c ^ (b | ~d))
213
214/* Process LEN bytes of BUFFER, accumulating context into CTX.
215   It is assumed that LEN % 64 == 0.  */
216
217void
218md5_process_block (buffer, len, ctx)
219     const void *buffer;
220     size_t len;
221     struct md5_ctx *ctx;
222{
223  md5_uint32 correct_words[16];
224  const md5_uint32 *words = buffer;
225  size_t nwords = len / sizeof (md5_uint32);
226  const md5_uint32 *endp = words + nwords;
227  md5_uint32 A = ctx->A;
228  md5_uint32 B = ctx->B;
229  md5_uint32 C = ctx->C;
230  md5_uint32 D = ctx->D;
231
232  /* Process all bytes in the buffer with 64 bytes in each round of
233     the loop.  */
234  while (words < endp)
235    {
236      md5_uint32 *cwp = correct_words;
237      md5_uint32 A_save = A;
238      md5_uint32 B_save = B;
239      md5_uint32 C_save = C;
240      md5_uint32 D_save = D;
241
242      /* First round: using the given function, the context and a constant
243	 the next context is computed.  Because the algorithms processing
244	 unit is a 32-bit word and it is determined to work on words in
245	 little endian byte order we perhaps have to change the byte order
246	 before the computation.  To reduce the work for the next steps
247	 we store the swapped words in the array CORRECT_WORDS.  */
248
249#define OP(a, b, c, d, s, T)						\
250      do								\
251        {								\
252	  a += FF (b, c, d) + (*cwp++ = SWAP (*words)) + T;		\
253	  ++words;							\
254	  CYCLIC (a, s);						\
255	  a += b;							\
256        }								\
257      while (0)
258
259      /* It is unfortunate that C does not provide an operator for
260	 cyclic rotation.  Hope the C compiler is smart enough.  */
261#define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))
262
263      /* Before we start, one word to the strange constants.
264	 They are defined in RFC 1321 as
265
266	 T[i] = (int) (4294967296.0 * fabs (sin (i))), i=1..64
267       */
268
269      /* Round 1.  */
270      OP (A, B, C, D,  7, 0xd76aa478);
271      OP (D, A, B, C, 12, 0xe8c7b756);
272      OP (C, D, A, B, 17, 0x242070db);
273      OP (B, C, D, A, 22, 0xc1bdceee);
274      OP (A, B, C, D,  7, 0xf57c0faf);
275      OP (D, A, B, C, 12, 0x4787c62a);
276      OP (C, D, A, B, 17, 0xa8304613);
277      OP (B, C, D, A, 22, 0xfd469501);
278      OP (A, B, C, D,  7, 0x698098d8);
279      OP (D, A, B, C, 12, 0x8b44f7af);
280      OP (C, D, A, B, 17, 0xffff5bb1);
281      OP (B, C, D, A, 22, 0x895cd7be);
282      OP (A, B, C, D,  7, 0x6b901122);
283      OP (D, A, B, C, 12, 0xfd987193);
284      OP (C, D, A, B, 17, 0xa679438e);
285      OP (B, C, D, A, 22, 0x49b40821);
286
287      /* For the second to fourth round we have the possibly swapped words
288	 in CORRECT_WORDS.  Redefine the macro to take an additional first
289	 argument specifying the function to use.  */
290#undef OP
291#define OP(f, a, b, c, d, k, s, T)					\
292      do 								\
293	{								\
294	  a += f (b, c, d) + correct_words[k] + T;			\
295	  CYCLIC (a, s);						\
296	  a += b;							\
297	}								\
298      while (0)
299
300      /* Round 2.  */
301      OP (FG, A, B, C, D,  1,  5, 0xf61e2562);
302      OP (FG, D, A, B, C,  6,  9, 0xc040b340);
303      OP (FG, C, D, A, B, 11, 14, 0x265e5a51);
304      OP (FG, B, C, D, A,  0, 20, 0xe9b6c7aa);
305      OP (FG, A, B, C, D,  5,  5, 0xd62f105d);
306      OP (FG, D, A, B, C, 10,  9, 0x02441453);
307      OP (FG, C, D, A, B, 15, 14, 0xd8a1e681);
308      OP (FG, B, C, D, A,  4, 20, 0xe7d3fbc8);
309      OP (FG, A, B, C, D,  9,  5, 0x21e1cde6);
310      OP (FG, D, A, B, C, 14,  9, 0xc33707d6);
311      OP (FG, C, D, A, B,  3, 14, 0xf4d50d87);
312      OP (FG, B, C, D, A,  8, 20, 0x455a14ed);
313      OP (FG, A, B, C, D, 13,  5, 0xa9e3e905);
314      OP (FG, D, A, B, C,  2,  9, 0xfcefa3f8);
315      OP (FG, C, D, A, B,  7, 14, 0x676f02d9);
316      OP (FG, B, C, D, A, 12, 20, 0x8d2a4c8a);
317
318      /* Round 3.  */
319      OP (FH, A, B, C, D,  5,  4, 0xfffa3942);
320      OP (FH, D, A, B, C,  8, 11, 0x8771f681);
321      OP (FH, C, D, A, B, 11, 16, 0x6d9d6122);
322      OP (FH, B, C, D, A, 14, 23, 0xfde5380c);
323      OP (FH, A, B, C, D,  1,  4, 0xa4beea44);
324      OP (FH, D, A, B, C,  4, 11, 0x4bdecfa9);
325      OP (FH, C, D, A, B,  7, 16, 0xf6bb4b60);
326      OP (FH, B, C, D, A, 10, 23, 0xbebfbc70);
327      OP (FH, A, B, C, D, 13,  4, 0x289b7ec6);
328      OP (FH, D, A, B, C,  0, 11, 0xeaa127fa);
329      OP (FH, C, D, A, B,  3, 16, 0xd4ef3085);
330      OP (FH, B, C, D, A,  6, 23, 0x04881d05);
331      OP (FH, A, B, C, D,  9,  4, 0xd9d4d039);
332      OP (FH, D, A, B, C, 12, 11, 0xe6db99e5);
333      OP (FH, C, D, A, B, 15, 16, 0x1fa27cf8);
334      OP (FH, B, C, D, A,  2, 23, 0xc4ac5665);
335
336      /* Round 4.  */
337      OP (FI, A, B, C, D,  0,  6, 0xf4292244);
338      OP (FI, D, A, B, C,  7, 10, 0x432aff97);
339      OP (FI, C, D, A, B, 14, 15, 0xab9423a7);
340      OP (FI, B, C, D, A,  5, 21, 0xfc93a039);
341      OP (FI, A, B, C, D, 12,  6, 0x655b59c3);
342      OP (FI, D, A, B, C,  3, 10, 0x8f0ccc92);
343      OP (FI, C, D, A, B, 10, 15, 0xffeff47d);
344      OP (FI, B, C, D, A,  1, 21, 0x85845dd1);
345      OP (FI, A, B, C, D,  8,  6, 0x6fa87e4f);
346      OP (FI, D, A, B, C, 15, 10, 0xfe2ce6e0);
347      OP (FI, C, D, A, B,  6, 15, 0xa3014314);
348      OP (FI, B, C, D, A, 13, 21, 0x4e0811a1);
349      OP (FI, A, B, C, D,  4,  6, 0xf7537e82);
350      OP (FI, D, A, B, C, 11, 10, 0xbd3af235);
351      OP (FI, C, D, A, B,  2, 15, 0x2ad7d2bb);
352      OP (FI, B, C, D, A,  9, 21, 0xeb86d391);
353
354      /* Add the starting values of the context.  */
355      A += A_save;
356      B += B_save;
357      C += C_save;
358      D += D_save;
359    }
360
361  /* Put checksum in context given as argument.  */
362  ctx->A = A;
363  ctx->B = B;
364  ctx->C = C;
365  ctx->D = D;
366}
367