freshlybakedca.ke
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1/*
2 * SHA1 routine optimized to do word accesses rather than byte accesses,
3 * and to avoid unnecessary copies into the context array.
4 *
5 * This was initially based on the Mozilla SHA1 implementation, although
6 * none of the original Mozilla code remains.
7 */
8
9/* this is only to get definitions for memcpy(), ntohl() and htonl() */
10#include "../git-compat-util.h"
11
12#include "sha1.h"
13
14#define SHA_ROT(X,l,r) (((X) << (l)) | ((X) >> (r)))
15#define SHA_ROL(X,n) SHA_ROT(X,n,32-(n))
16#define SHA_ROR(X,n) SHA_ROT(X,32-(n),n)
17
18/*
19 * If you have 32 registers or more, the compiler can (and should)
20 * try to change the array[] accesses into registers. However, on
21 * machines with less than ~25 registers, that won't really work,
22 * and at least gcc will make an unholy mess of it.
23 *
24 * So to avoid that mess which just slows things down, we force
25 * the stores to memory to actually happen (we might be better off
26 * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
27 * suggested by Artur Skawina - that will also make gcc unable to
28 * try to do the silly "optimize away loads" part because it won't
29 * see what the value will be).
30 *
31 * On ARM we get the best code generation by forcing a full memory barrier
32 * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
33 * the stack frame size simply explode and performance goes down the drain.
34 */
35
36#if defined(__i386__) || defined(__x86_64__)
37 #define setW(x, val) (*(volatile unsigned int *)&W(x) = (val))
38#elif defined(__GNUC__) && defined(__arm__)
39 #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
40#else
41 #define setW(x, val) (W(x) = (val))
42#endif
43
44/* This "rolls" over the 512-bit array */
45#define W(x) (array[(x)&15])
46
47/*
48 * Where do we get the source from? The first 16 iterations get it from
49 * the input data, the next mix it from the 512-bit array.
50 */
51#define SHA_SRC(t) get_be32((unsigned char *) block + (t)*4)
52#define SHA_MIX(t) SHA_ROL(W((t)+13) ^ W((t)+8) ^ W((t)+2) ^ W(t), 1)
53
54#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
55 unsigned int TEMP = input(t); setW(t, TEMP); \
56 E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \
57 B = SHA_ROR(B, 2); } while (0)
58
59#define T_0_15(t, A, B, C, D, E) SHA_ROUND(t, SHA_SRC, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
60#define T_16_19(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (((C^D)&B)^D) , 0x5a827999, A, B, C, D, E )
61#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
62#define T_40_59(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, ((B&C)+(D&(B^C))) , 0x8f1bbcdc, A, B, C, D, E )
63#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0xca62c1d6, A, B, C, D, E )
64
65static void blk_SHA1_Block(blk_SHA_CTX *ctx, const void *block)
66{
67 unsigned int A,B,C,D,E;
68 unsigned int array[16];
69
70 A = ctx->H[0];
71 B = ctx->H[1];
72 C = ctx->H[2];
73 D = ctx->H[3];
74 E = ctx->H[4];
75
76 /* Round 1 - iterations 0-16 take their input from 'block' */
77 T_0_15( 0, A, B, C, D, E);
78 T_0_15( 1, E, A, B, C, D);
79 T_0_15( 2, D, E, A, B, C);
80 T_0_15( 3, C, D, E, A, B);
81 T_0_15( 4, B, C, D, E, A);
82 T_0_15( 5, A, B, C, D, E);
83 T_0_15( 6, E, A, B, C, D);
84 T_0_15( 7, D, E, A, B, C);
85 T_0_15( 8, C, D, E, A, B);
86 T_0_15( 9, B, C, D, E, A);
87 T_0_15(10, A, B, C, D, E);
88 T_0_15(11, E, A, B, C, D);
89 T_0_15(12, D, E, A, B, C);
90 T_0_15(13, C, D, E, A, B);
91 T_0_15(14, B, C, D, E, A);
92 T_0_15(15, A, B, C, D, E);
93
94 /* Round 1 - tail. Input from 512-bit mixing array */
95 T_16_19(16, E, A, B, C, D);
96 T_16_19(17, D, E, A, B, C);
97 T_16_19(18, C, D, E, A, B);
98 T_16_19(19, B, C, D, E, A);
99
100 /* Round 2 */
101 T_20_39(20, A, B, C, D, E);
102 T_20_39(21, E, A, B, C, D);
103 T_20_39(22, D, E, A, B, C);
104 T_20_39(23, C, D, E, A, B);
105 T_20_39(24, B, C, D, E, A);
106 T_20_39(25, A, B, C, D, E);
107 T_20_39(26, E, A, B, C, D);
108 T_20_39(27, D, E, A, B, C);
109 T_20_39(28, C, D, E, A, B);
110 T_20_39(29, B, C, D, E, A);
111 T_20_39(30, A, B, C, D, E);
112 T_20_39(31, E, A, B, C, D);
113 T_20_39(32, D, E, A, B, C);
114 T_20_39(33, C, D, E, A, B);
115 T_20_39(34, B, C, D, E, A);
116 T_20_39(35, A, B, C, D, E);
117 T_20_39(36, E, A, B, C, D);
118 T_20_39(37, D, E, A, B, C);
119 T_20_39(38, C, D, E, A, B);
120 T_20_39(39, B, C, D, E, A);
121
122 /* Round 3 */
123 T_40_59(40, A, B, C, D, E);
124 T_40_59(41, E, A, B, C, D);
125 T_40_59(42, D, E, A, B, C);
126 T_40_59(43, C, D, E, A, B);
127 T_40_59(44, B, C, D, E, A);
128 T_40_59(45, A, B, C, D, E);
129 T_40_59(46, E, A, B, C, D);
130 T_40_59(47, D, E, A, B, C);
131 T_40_59(48, C, D, E, A, B);
132 T_40_59(49, B, C, D, E, A);
133 T_40_59(50, A, B, C, D, E);
134 T_40_59(51, E, A, B, C, D);
135 T_40_59(52, D, E, A, B, C);
136 T_40_59(53, C, D, E, A, B);
137 T_40_59(54, B, C, D, E, A);
138 T_40_59(55, A, B, C, D, E);
139 T_40_59(56, E, A, B, C, D);
140 T_40_59(57, D, E, A, B, C);
141 T_40_59(58, C, D, E, A, B);
142 T_40_59(59, B, C, D, E, A);
143
144 /* Round 4 */
145 T_60_79(60, A, B, C, D, E);
146 T_60_79(61, E, A, B, C, D);
147 T_60_79(62, D, E, A, B, C);
148 T_60_79(63, C, D, E, A, B);
149 T_60_79(64, B, C, D, E, A);
150 T_60_79(65, A, B, C, D, E);
151 T_60_79(66, E, A, B, C, D);
152 T_60_79(67, D, E, A, B, C);
153 T_60_79(68, C, D, E, A, B);
154 T_60_79(69, B, C, D, E, A);
155 T_60_79(70, A, B, C, D, E);
156 T_60_79(71, E, A, B, C, D);
157 T_60_79(72, D, E, A, B, C);
158 T_60_79(73, C, D, E, A, B);
159 T_60_79(74, B, C, D, E, A);
160 T_60_79(75, A, B, C, D, E);
161 T_60_79(76, E, A, B, C, D);
162 T_60_79(77, D, E, A, B, C);
163 T_60_79(78, C, D, E, A, B);
164 T_60_79(79, B, C, D, E, A);
165
166 ctx->H[0] += A;
167 ctx->H[1] += B;
168 ctx->H[2] += C;
169 ctx->H[3] += D;
170 ctx->H[4] += E;
171}
172
173void blk_SHA1_Init(blk_SHA_CTX *ctx)
174{
175 ctx->size = 0;
176
177 /* Initialize H with the magic constants (see FIPS180 for constants) */
178 ctx->H[0] = 0x67452301;
179 ctx->H[1] = 0xefcdab89;
180 ctx->H[2] = 0x98badcfe;
181 ctx->H[3] = 0x10325476;
182 ctx->H[4] = 0xc3d2e1f0;
183}
184
185void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, size_t len)
186{
187 unsigned int lenW = ctx->size & 63;
188
189 ctx->size += len;
190
191 /* Read the data into W and process blocks as they get full */
192 if (lenW) {
193 unsigned int left = 64 - lenW;
194 if (len < left)
195 left = len;
196 memcpy(lenW + (char *)ctx->W, data, left);
197 lenW = (lenW + left) & 63;
198 len -= left;
199 data = ((const char *)data + left);
200 if (lenW)
201 return;
202 blk_SHA1_Block(ctx, ctx->W);
203 }
204 while (len >= 64) {
205 blk_SHA1_Block(ctx, data);
206 data = ((const char *)data + 64);
207 len -= 64;
208 }
209 if (len)
210 memcpy(ctx->W, data, len);
211}
212
213void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
214{
215 static const unsigned char pad[64] = { 0x80 };
216 unsigned int padlen[2];
217 int i;
218
219 /* Pad with a binary 1 (ie 0x80), then zeroes, then length */
220 padlen[0] = htonl((uint32_t)(ctx->size >> 29));
221 padlen[1] = htonl((uint32_t)(ctx->size << 3));
222
223 i = ctx->size & 63;
224 blk_SHA1_Update(ctx, pad, 1 + (63 & (55 - i)));
225 blk_SHA1_Update(ctx, padlen, 8);
226
227 /* Output hash */
228 for (i = 0; i < 5; i++)
229 put_be32(hashout + i * 4, ctx->H[i]);
230}