1 /* $Id$ */
2 /*
3 * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17 #include "config.h"
18
19 #include <sys/types.h>
20 #include COMPAT_ENDIAN_H
21
22 #include <assert.h>
23 #include <assert.h>
24 #include <stdint.h>
25 #include <stdlib.h>
26
27 #include "extern.h"
28 #include "md4.h"
29
30 /*
31 * A fast 32-bit hash.
32 * Described in Tridgell's "Efficient Algorithms for Sorting and
33 * Synchronization" thesis and the "Rolling checksum" document.
34 */
35 uint32_t
hash_fast(const void * buf,size_t len)36 hash_fast(const void *buf, size_t len)
37 {
38 size_t i = 0;
39 uint32_t a = 0, /* part of a(k, l) */
40 b = 0; /* b(k, l) */
41 const signed char *dat = buf;
42
43 if (len > 4)
44 for ( ; i < len - 4; i += 4) {
45 b += 4 * (a + dat[i]) +
46 3 * dat[i + 1] +
47 2 * dat[i + 2] +
48 dat[i + 3];
49 a += dat[i + 0] +
50 dat[i + 1] +
51 dat[i + 2] +
52 dat[i + 3];
53 }
54
55 for ( ; i < len; i++) {
56 a += dat[i];
57 b += a;
58 }
59
60 /* s(k, l) = (eps % M) + 2^16 b(k, l) % M */
61
62 return (a & 0xffff) + (b << 16);
63 }
64
65 /*
66 * Slow MD4-based hash with trailing seed.
67 */
68 void
hash_slow(const void * buf,size_t len,unsigned char * md,const struct sess * sess)69 hash_slow(const void *buf, size_t len,
70 unsigned char *md, const struct sess *sess)
71 {
72 MD4_CTX ctx;
73 int32_t seed = htole32(sess->seed);
74
75 MD4_Init(&ctx);
76 MD4_Update(&ctx, buf, len);
77 MD4_Update(&ctx, (unsigned char *)&seed, sizeof(int32_t));
78 MD4_Final(md, &ctx);
79 }
80
81 /*
82 * Hash an entire file.
83 * This is similar to hash_slow() except the seed is hashed at the end
84 * of the sequence, not the beginning.
85 */
86 void
hash_file(const void * buf,size_t len,unsigned char * md,const struct sess * sess)87 hash_file(const void *buf, size_t len,
88 unsigned char *md, const struct sess *sess)
89 {
90 MD4_CTX ctx;
91 int32_t seed = htole32(sess->seed);
92
93 MD4_Init(&ctx);
94 MD4_Update(&ctx, (unsigned char *)&seed, sizeof(int32_t));
95 MD4_Update(&ctx, buf, len);
96 MD4_Final(md, &ctx);
97 }
98