summaryrefslogtreecommitdiffstats
path: root/md5.c
blob: ec24dd21fb40be80996651a84d821bab6a64d0d2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
/*
 *  md5.c - Compute MD5 checksum of strings according to the
 *          definition of MD5 in RFC 1321 from April 1992.
 *
 *  Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, 1995.
 *
 *  Copyright (C) 1995-1999 Free Software Foundation, Inc.
 *  Copyright (C) 2001 Manuel Novoa III
 *  Copyright (C) 2003 Glenn L. McGrath
 *  Copyright (C) 2003 Erik Andersen
 *
 *  Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 */

#include <libubox/blob.h> /* TODO: better include for bswap_32 compat */
#include "md5.h"

#if __BYTE_ORDER == __LITTLE_ENDIAN
#define SWAP_LE32(x) (x)
#else
#define SWAP_LE32(x) bswap_32(x)
#endif

/* Initialize structure containing state of computation.
 * (RFC 1321, 3.3: Step 3)
 */
void md5_begin(md5_ctx_t *ctx)
{
	ctx->A = 0x67452301;
	ctx->B = 0xefcdab89;
	ctx->C = 0x98badcfe;
	ctx->D = 0x10325476;

	ctx->total = 0;
	ctx->buflen = 0;
}

/* 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))
 */
# define FF(b, c, d) (d ^ (b & (c ^ d)))
# define FG(b, c, d) FF (d, b, c)
# define FH(b, c, d) (b ^ c ^ d)
# define FI(b, c, d) (c ^ (b | ~d))

/* Hash a single block, 64 bytes long and 4-byte aligned. */
static void md5_hash_block(const void *buffer, md5_ctx_t *ctx)
{
	uint32_t correct_words[16];
	const uint32_t *words = buffer;

	static const uint32_t C_array[] = {
		/* round 1 */
		0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
		0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
		0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
		0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
		/* round 2 */
		0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
		0xd62f105d, 0x2441453, 0xd8a1e681, 0xe7d3fbc8,
		0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
		0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
		/* round 3 */
		0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
		0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
		0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x4881d05,
		0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
		/* round 4 */
		0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
		0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
		0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
		0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
	};

	static const char P_array[] = {
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,	/* 1 */
		1, 6, 11, 0, 5, 10, 15, 4, 9, 14, 3, 8, 13, 2, 7, 12,	/* 2 */
		5, 8, 11, 14, 1, 4, 7, 10, 13, 0, 3, 6, 9, 12, 15, 2,	/* 3 */
		0, 7, 14, 5, 12, 3, 10, 1, 8, 15, 6, 13, 4, 11, 2, 9	/* 4 */
	};

	static const char S_array[] = {
		7, 12, 17, 22,
		5, 9, 14, 20,
		4, 11, 16, 23,
		6, 10, 15, 21
	};

	uint32_t A = ctx->A;
	uint32_t B = ctx->B;
	uint32_t C = ctx->C;
	uint32_t D = ctx->D;

	uint32_t *cwp = correct_words;

#  define CYCLIC(w, s) (w = (w << s) | (w >> (32 - s)))

	const uint32_t *pc;
	const char *pp;
	const char *ps;
	int i;
	uint32_t temp;

	for (i = 0; i < 16; i++) {
		cwp[i] = SWAP_LE32(words[i]);
	}
	words += 16;

	pc = C_array;
	pp = P_array;
	ps = S_array;

	for (i = 0; i < 16; i++) {
		temp = A + FF(B, C, D) + cwp[(int) (*pp++)] + *pc++;
		CYCLIC(temp, ps[i & 3]);
		temp += B;
		A = D;
		D = C;
		C = B;
		B = temp;
	}

	ps += 4;
	for (i = 0; i < 16; i++) {
		temp = A + FG(B, C, D) + cwp[(int) (*pp++)] + *pc++;
		CYCLIC(temp, ps[i & 3]);
		temp += B;
		A = D;
		D = C;
		C = B;
		B = temp;
	}
	ps += 4;
	for (i = 0; i < 16; i++) {
		temp = A + FH(B, C, D) + cwp[(int) (*pp++)] + *pc++;
		CYCLIC(temp, ps[i & 3]);
		temp += B;
		A = D;
		D = C;
		C = B;
		B = temp;
	}
	ps += 4;
	for (i = 0; i < 16; i++) {
		temp = A + FI(B, C, D) + cwp[(int) (*pp++)] + *pc++;
		CYCLIC(temp, ps[i & 3]);
		temp += B;
		A = D;
		D = C;
		C = B;
		B = temp;
	}


	ctx->A += A;
	ctx->B += B;
	ctx->C += C;
	ctx->D += D;
}

/* Feed data through a temporary buffer to call md5_hash_aligned_block()
 * with chunks of data that are 4-byte aligned and a multiple of 64 bytes.
 * This function's internal buffer remembers previous data until it has 64
 * bytes worth to pass on.  Call md5_end() to flush this buffer. */

void md5_hash(const void *buffer, size_t len, md5_ctx_t *ctx)
{
	char *buf = (char *)buffer;

	/* RFC 1321 specifies the possible length of the file up to 2^64 bits,
	 * Here we only track the number of bytes.  */

	ctx->total += len;

	// Process all input.

	while (len) {
		unsigned i = 64 - ctx->buflen;

		// Copy data into aligned buffer.

		if (i > len)
			i = len;
		memcpy(ctx->buffer + ctx->buflen, buf, i);
		len -= i;
		ctx->buflen += i;
		buf += i;

		// When buffer fills up, process it.

		if (ctx->buflen == 64) {
			md5_hash_block(ctx->buffer, ctx);
			ctx->buflen = 0;
		}
	}
}

/* Process the remaining bytes in the buffer and put result from CTX
 * in first 16 bytes following RESBUF.  The result is always in little
 * endian byte order, so that a byte-wise output yields to the wanted
 * ASCII representation of the message digest.
 *
 * IMPORTANT: On some systems it is required that RESBUF is correctly
 * aligned for a 32 bits value.
 */
void md5_end(void *resbuf, md5_ctx_t *ctx)
{
	char *buf = ctx->buffer;
	int i;

	/* Pad data to block size.  */

	buf[ctx->buflen++] = 0x80;
	memset(buf + ctx->buflen, 0, 128 - ctx->buflen);

	/* Put the 64-bit file length in *bits* at the end of the buffer.  */
	ctx->total <<= 3;
	if (ctx->buflen > 56)
		buf += 64;

	for (i = 0; i < 8; i++)
		buf[56 + i] = ctx->total >> (i*8);

	/* Process last bytes.  */
	if (buf != ctx->buffer)
		md5_hash_block(ctx->buffer, ctx);
	md5_hash_block(buf, ctx);

	/* Put result from CTX in first 16 bytes following RESBUF.  The result is
	 * always in little endian byte order, so that a byte-wise output yields
	 * to the wanted ASCII representation of the message digest.
	 *
	 * IMPORTANT: On some systems it is required that RESBUF is correctly
	 * aligned for a 32 bits value.
	 */
	((uint32_t *) resbuf)[0] = SWAP_LE32(ctx->A);
	((uint32_t *) resbuf)[1] = SWAP_LE32(ctx->B);
	((uint32_t *) resbuf)[2] = SWAP_LE32(ctx->C);
	((uint32_t *) resbuf)[3] = SWAP_LE32(ctx->D);
}