1 /* 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) 1995-2023 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20 /* Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995. */
21
22 #ifdef HAVE_CONFIG_H
23 # include <config.h>
24 #endif
25
26 #include <sys/types.h>
27
28 #if STDC_HEADERS || defined _LIBC
29 # include <stdlib.h>
30 # include <string.h>
31 #else
32 # ifndef HAVE_MEMCPY
33 # define memcpy(d, s, n) (bcopy ((s), (d), (n)), (d))
34 # endif
35 #endif
36
37 #include "md5.h"
38
39 #ifdef _LIBC
40 # include <endian.h>
41 # if __BYTE_ORDER == __BIG_ENDIAN
42 # define WORDS_BIGENDIAN 1
43 # endif
44 /* We need to keep the namespace clean so define the MD5 function
45 protected using leading __ . */
46 # define md5_init_ctx __md5_init_ctx
47 # define md5_process_bytes __md5_process_bytes
48 # define md5_finish_ctx __md5_finish_ctx
49 # define md5_read_ctx __md5_read_ctx
50 # define md5_stream __md5_stream
51 # define md5_buffer __md5_buffer
52 #endif
53
54 #ifdef WORDS_BIGENDIAN
55 # define SWAP(n) \
56 (((n) << 24) | (((n) & 0xff00) << 8) | (((n) >> 8) & 0xff00) | ((n) >> 24))
57 #else
58 # define SWAP(n) (n)
59 #endif
60
61
62 /* This array contains the bytes used to pad the buffer to the next
63 64-byte boundary. (RFC 1321, 3.1: Step 1) */
64 static const unsigned char fillbuf[64] = { 0x80, 0 /* , 0, 0, ... */ };
65
66
67 /* Initialize structure containing state of computation.
68 (RFC 1321, 3.3: Step 3) */
69 void
70 md5_init_ctx (struct md5_ctx *ctx)
71 {
72 ctx->A = 0x67452301;
73 ctx->B = 0xefcdab89;
74 ctx->C = 0x98badcfe;
75 ctx->D = 0x10325476;
76
77 ctx->total[0] = ctx->total[1] = 0;
78 ctx->buflen = 0;
79 }
80
81 /* Put result from CTX in first 16 bytes following RESBUF. The result
82 must be in little endian byte order.
83
84 IMPORTANT: On some systems it is required that RESBUF is correctly
85 aligned for a 32 bits value. */
86 void *
87 md5_read_ctx (const struct md5_ctx *ctx, void *resbuf)
88 {
89 ((md5_uint32 *) resbuf)[0] = SWAP (ctx->A);
90 ((md5_uint32 *) resbuf)[1] = SWAP (ctx->B);
91 ((md5_uint32 *) resbuf)[2] = SWAP (ctx->C);
92 ((md5_uint32 *) resbuf)[3] = SWAP (ctx->D);
93
94 return resbuf;
95 }
96
97 /* Process the remaining bytes in the internal buffer and the usual
98 prolog according to the standard and write the result to RESBUF.
99
100 IMPORTANT: On some systems it is required that RESBUF is correctly
101 aligned for a 32 bits value. */
102 void *
103 md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
104 {
105 /* Take yet unprocessed bytes into account. */
106 md5_uint32 bytes = ctx->buflen;
107 size_t pad;
108
109 /* Now count remaining bytes. */
110 ctx->total[0] += bytes;
111 if (ctx->total[0] < bytes)
112 ++ctx->total[1];
113
114 pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
115 memcpy (&ctx->buffer[bytes], fillbuf, pad);
116
117 /* Put the 64-bit file length in *bits* at the end of the buffer. */
118 ctx->buffer32[(bytes + pad) / 4] = SWAP (ctx->total[0] << 3);
119 ctx->buffer32[(bytes + pad + 4) / 4] = SWAP ((ctx->total[1] << 3)
120 | (ctx->total[0] >> 29));
121
122 /* Process last bytes. */
123 __md5_process_block (ctx->buffer, bytes + pad + 8, ctx);
124
125 return md5_read_ctx (ctx, resbuf);
126 }
127
128 /* Compute MD5 message digest for bytes read from STREAM. The
129 resulting message digest number will be written into the 16 bytes
130 beginning at RESBLOCK. */
131 int
132 md5_stream (FILE *stream, void *resblock)
133 {
134 /* Important: BLOCKSIZE must be a multiple of 64. */
135 #define BLOCKSIZE 4096
136 struct md5_ctx ctx;
137 char buffer[BLOCKSIZE + 72];
138 size_t sum;
139
140 /* Initialize the computation context. */
141 md5_init_ctx (&ctx);
142
143 /* Iterate over full file contents. */
144 while (1)
145 {
146 /* We read the file in blocks of BLOCKSIZE bytes. One call of the
147 computation function processes the whole buffer so that with the
148 next round of the loop another block can be read. */
149 size_t n;
150 sum = 0;
151
152 /* Read block. Take care for partial reads. */
153 do
154 {
155 n = fread (buffer + sum, 1, BLOCKSIZE - sum, stream);
156
157 sum += n;
158 }
159 while (sum < BLOCKSIZE && n != 0);
160 if (n == 0 && ferror (stream))
161 return 1;
162
163 /* If end of file is reached, end the loop. */
164 if (n == 0)
165 break;
166
167 /* Process buffer with BLOCKSIZE bytes. Note that
168 BLOCKSIZE % 64 == 0
169 */
170 __md5_process_block (buffer, BLOCKSIZE, &ctx);
171 }
172
173 /* Add the last bytes if necessary. */
174 if (sum > 0)
175 md5_process_bytes (buffer, sum, &ctx);
176
177 /* Construct result in desired memory. */
178 md5_finish_ctx (&ctx, resblock);
179 return 0;
180 }
181
182 /* Compute MD5 message digest for LEN bytes beginning at BUFFER. The
183 result is always in little endian byte order, so that a byte-wise
184 output yields to the wanted ASCII representation of the message
185 digest. */
186 void *
187 md5_buffer (const char *buffer, size_t len, void *resblock)
188 {
189 struct md5_ctx ctx;
190
191 /* Initialize the computation context. */
192 md5_init_ctx (&ctx);
193
194 /* Process whole buffer but last len % 64 bytes. */
195 md5_process_bytes (buffer, len, &ctx);
196
197 /* Put result in desired memory area. */
198 return md5_finish_ctx (&ctx, resblock);
199 }
200
201
202 void
203 md5_process_bytes (const void *buffer, size_t len, struct md5_ctx *ctx)
204 {
205 /* When we already have some bits in our internal buffer concatenate
206 both inputs first. */
207 if (ctx->buflen != 0)
208 {
209 size_t left_over = ctx->buflen;
210 size_t add = 128 - left_over > len ? len : 128 - left_over;
211
212 memcpy (&ctx->buffer[left_over], buffer, add);
213 ctx->buflen += add;
214
215 if (ctx->buflen > 64)
216 {
217 __md5_process_block (ctx->buffer, ctx->buflen & ~63, ctx);
218
219 ctx->buflen &= 63;
220 /* The regions in the following copy operation cannot overlap. */
221 memcpy (ctx->buffer, &ctx->buffer[(left_over + add) & ~63],
222 ctx->buflen);
223 }
224
225 buffer = (const char *) buffer + add;
226 len -= add;
227 }
228
229 /* Process available complete blocks. */
230 if (len >= 64)
231 {
232 while (len > 64)
233 {
234 __md5_process_block (memcpy (ctx->buffer, buffer, 64), 64, ctx);
235 buffer = (const char *) buffer + 64;
236 len -= 64;
237 }
238 }
239
240 /* Move remaining bytes in internal buffer. */
241 if (len > 0)
242 {
243 size_t left_over = ctx->buflen;
244
245 memcpy (&ctx->buffer[left_over], buffer, len);
246 left_over += len;
247 if (left_over >= 64)
248 {
249 __md5_process_block (ctx->buffer, 64, ctx);
250 left_over -= 64;
251 memcpy (ctx->buffer, &ctx->buffer[64], left_over);
252 }
253 ctx->buflen = left_over;
254 }
255 }
256
257 #include <md5-block.c>