1 // SPDX-License-Identifier: BSD-2-Clause
2 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
3 *
4 * LibTomCrypt is a library that provides various cryptographic
5 * algorithms in a highly modular and flexible manner.
6 *
7 * The library is free for all purposes without any express
8 * guarantee it works.
9 */
10 #include "tomcrypt_private.h"
11
12 /**
13 @file adler32.c
14 Adler-32 checksum algorithm
15 Written and placed in the public domain by Wei Dai
16 Adapted for libtomcrypt by Steffen Jaeckel
17 */
18 #ifdef LTC_ADLER32
19
20 static const unsigned long _adler32_base = 65521;
21
adler32_init(adler32_state * ctx)22 void adler32_init(adler32_state *ctx)
23 {
24 LTC_ARGCHKVD(ctx != NULL);
25 ctx->s[0] = 1;
26 ctx->s[1] = 0;
27 }
28
adler32_update(adler32_state * ctx,const unsigned char * input,unsigned long length)29 void adler32_update(adler32_state *ctx, const unsigned char *input, unsigned long length)
30 {
31 unsigned long s1, s2;
32
33 LTC_ARGCHKVD(ctx != NULL);
34 LTC_ARGCHKVD(input != NULL);
35 s1 = ctx->s[0];
36 s2 = ctx->s[1];
37
38 if (length % 8 != 0) {
39 do {
40 s1 += *input++;
41 s2 += s1;
42 length--;
43 } while (length % 8 != 0);
44
45 if (s1 >= _adler32_base) {
46 s1 -= _adler32_base;
47 }
48 s2 %= _adler32_base;
49 }
50
51 while (length > 0) {
52 s1 += input[0];
53 s2 += s1;
54 s1 += input[1];
55 s2 += s1;
56 s1 += input[2];
57 s2 += s1;
58 s1 += input[3];
59 s2 += s1;
60 s1 += input[4];
61 s2 += s1;
62 s1 += input[5];
63 s2 += s1;
64 s1 += input[6];
65 s2 += s1;
66 s1 += input[7];
67 s2 += s1;
68
69 length -= 8;
70 input += 8;
71
72 if (s1 >= _adler32_base) {
73 s1 -= _adler32_base;
74 }
75 s2 %= _adler32_base;
76 }
77
78 LTC_ARGCHKVD(s1 < _adler32_base);
79 LTC_ARGCHKVD(s2 < _adler32_base);
80
81 ctx->s[0] = (unsigned short)s1;
82 ctx->s[1] = (unsigned short)s2;
83 }
84
adler32_finish(const adler32_state * ctx,void * hash,unsigned long size)85 void adler32_finish(const adler32_state *ctx, void *hash, unsigned long size)
86 {
87 unsigned char* h;
88
89 LTC_ARGCHKVD(ctx != NULL);
90 LTC_ARGCHKVD(hash != NULL);
91
92 h = hash;
93
94 switch (size) {
95 default:
96 h[3] = ctx->s[0] & 0x0ff;
97 /* FALLTHROUGH */
98 case 3:
99 h[2] = (ctx->s[0] >> 8) & 0x0ff;
100 /* FALLTHROUGH */
101 case 2:
102 h[1] = ctx->s[1] & 0x0ff;
103 /* FALLTHROUGH */
104 case 1:
105 h[0] = (ctx->s[1] >> 8) & 0x0ff;
106 /* FALLTHROUGH */
107 case 0:
108 ;
109 }
110 }
111
adler32_test(void)112 int adler32_test(void)
113 {
114 #ifndef LTC_TEST
115 return CRYPT_NOP;
116 #else
117 const void* in = "libtomcrypt";
118 const unsigned char adler32[] = { 0x1b, 0xe8, 0x04, 0xba };
119 unsigned char out[4];
120 adler32_state ctx;
121 adler32_init(&ctx);
122 adler32_update(&ctx, in, strlen(in));
123 adler32_finish(&ctx, out, 4);
124 if (compare_testvector(adler32, 4, out, 4, "adler32", 0)) {
125 return CRYPT_FAIL_TESTVECTOR;
126 }
127 return CRYPT_OK;
128 #endif
129 }
130 #endif
131
132 /* ref: $Format:%D$ */
133 /* git commit: $Format:%H$ */
134 /* commit time: $Format:%ai$ */
135