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comparison libtomcrypt/src/misc/adler32.c @ 1471:6dba84798cd5

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Update to libtomcrypt 1.18.1, merged with Dropbear changes
author Matt Johnston <matt@ucc.asn.au>
date Fri, 09 Feb 2018 21:44:05 +0800
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1470:8bba51a55704 1471:6dba84798cd5
1 /* LibTomCrypt, modular cryptographic library -- Tom St Denis
2 *
3 * LibTomCrypt is a library that provides various cryptographic
4 * algorithms in a highly modular and flexible manner.
5 *
6 * The library is free for all purposes without any express
7 * guarantee it works.
8 */
9 #include "tomcrypt.h"
10
11 /**
12 @file adler32.c
13 Adler-32 checksum algorithm
14 Written and placed in the public domain by Wei Dai
15 Adapted for libtomcrypt by Steffen Jaeckel
16 */
17 #ifdef LTC_ADLER32
18
19 static const unsigned long _adler32_base = 65521;
20
21 void adler32_init(adler32_state *ctx)
22 {
23 LTC_ARGCHKVD(ctx != NULL);
24 ctx->s[0] = 1;
25 ctx->s[1] = 0;
26 }
27
28 void adler32_update(adler32_state *ctx, const unsigned char *input, unsigned long length)
29 {
30 unsigned long s1, s2;
31
32 LTC_ARGCHKVD(ctx != NULL);
33 LTC_ARGCHKVD(input != NULL);
34 s1 = ctx->s[0];
35 s2 = ctx->s[1];
36
37 if (length % 8 != 0) {
38 do {
39 s1 += *input++;
40 s2 += s1;
41 length--;
42 } while (length % 8 != 0);
43
44 if (s1 >= _adler32_base)
45 s1 -= _adler32_base;
46 s2 %= _adler32_base;
47 }
48
49 while (length > 0) {
50 s1 += input[0];
51 s2 += s1;
52 s1 += input[1];
53 s2 += s1;
54 s1 += input[2];
55 s2 += s1;
56 s1 += input[3];
57 s2 += s1;
58 s1 += input[4];
59 s2 += s1;
60 s1 += input[5];
61 s2 += s1;
62 s1 += input[6];
63 s2 += s1;
64 s1 += input[7];
65 s2 += s1;
66
67 length -= 8;
68 input += 8;
69
70 if (s1 >= _adler32_base)
71 s1 -= _adler32_base;
72 s2 %= _adler32_base;
73 }
74
75 LTC_ARGCHKVD(s1 < _adler32_base);
76 LTC_ARGCHKVD(s2 < _adler32_base);
77
78 ctx->s[0] = (unsigned short)s1;
79 ctx->s[1] = (unsigned short)s2;
80 }
81
82 void adler32_finish(adler32_state *ctx, void *hash, unsigned long size)
83 {
84 unsigned char* h;
85
86 LTC_ARGCHKVD(ctx != NULL);
87 LTC_ARGCHKVD(hash != NULL);
88
89 h = hash;
90
91 switch (size) {
92 default:
93 h[3] = ctx->s[0] & 0x0ff;
94 /* FALLTHROUGH */
95 case 3:
96 h[2] = (ctx->s[0] >> 8) & 0x0ff;
97 /* FALLTHROUGH */
98 case 2:
99 h[1] = ctx->s[1] & 0x0ff;
100 /* FALLTHROUGH */
101 case 1:
102 h[0] = (ctx->s[1] >> 8) & 0x0ff;
103 /* FALLTHROUGH */
104 case 0:
105 ;
106 }
107 }
108
109 int adler32_test(void)
110 {
111 #ifndef LTC_TEST
112 return CRYPT_NOP;
113 #else
114 const void* in = "libtomcrypt";
115 const unsigned char adler32[] = { 0x1b, 0xe8, 0x04, 0xba };
116 unsigned char out[4];
117 adler32_state ctx;
118 adler32_init(&ctx);
119 adler32_update(&ctx, in, strlen(in));
120 adler32_finish(&ctx, out, 4);
121 if (compare_testvector(adler32, 4, out, 4, "adler32", 0)) {
122 return CRYPT_FAIL_TESTVECTOR;
123 }
124 return CRYPT_OK;
125 #endif
126 }
127 #endif
128
129 /* ref: $Format:%D$ */
130 /* git commit: $Format:%H$ */
131 /* commit time: $Format:%ai$ */