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Linux/lib/sha1.c

  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 based on the git SHA1 implementation.
  6  */
  7 
  8 #include <linux/kernel.h>
  9 #include <linux/export.h>
 10 #include <linux/bitops.h>
 11 #include <linux/cryptohash.h>
 12 #include <asm/unaligned.h>
 13 
 14 /*
 15  * If you have 32 registers or more, the compiler can (and should)
 16  * try to change the array[] accesses into registers. However, on
 17  * machines with less than ~25 registers, that won't really work,
 18  * and at least gcc will make an unholy mess of it.
 19  *
 20  * So to avoid that mess which just slows things down, we force
 21  * the stores to memory to actually happen (we might be better off
 22  * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
 23  * suggested by Artur Skawina - that will also make gcc unable to
 24  * try to do the silly "optimize away loads" part because it won't
 25  * see what the value will be).
 26  *
 27  * Ben Herrenschmidt reports that on PPC, the C version comes close
 28  * to the optimized asm with this (ie on PPC you don't want that
 29  * 'volatile', since there are lots of registers).
 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 #ifdef CONFIG_X86
 37   #define setW(x, val) (*(volatile __u32 *)&W(x) = (val))
 38 #elif defined(CONFIG_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_unaligned_be32((__u32 *)data + t)
 52 #define SHA_MIX(t) rol32(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         __u32 TEMP = input(t); setW(t, TEMP); \
 56         E += TEMP + rol32(A,5) + (fn) + (constant); \
 57         B = ror32(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 
 65 /**
 66  * sha_transform - single block SHA1 transform
 67  *
 68  * @digest: 160 bit digest to update
 69  * @data:   512 bits of data to hash
 70  * @array:  16 words of workspace (see note)
 71  *
 72  * This function generates a SHA1 digest for a single 512-bit block.
 73  * Be warned, it does not handle padding and message digest, do not
 74  * confuse it with the full FIPS 180-1 digest algorithm for variable
 75  * length messages.
 76  *
 77  * Note: If the hash is security sensitive, the caller should be sure
 78  * to clear the workspace. This is left to the caller to avoid
 79  * unnecessary clears between chained hashing operations.
 80  */
 81 void sha_transform(__u32 *digest, const char *data, __u32 *array)
 82 {
 83         __u32 A, B, C, D, E;
 84 
 85         A = digest[0];
 86         B = digest[1];
 87         C = digest[2];
 88         D = digest[3];
 89         E = digest[4];
 90 
 91         /* Round 1 - iterations 0-16 take their input from 'data' */
 92         T_0_15( 0, A, B, C, D, E);
 93         T_0_15( 1, E, A, B, C, D);
 94         T_0_15( 2, D, E, A, B, C);
 95         T_0_15( 3, C, D, E, A, B);
 96         T_0_15( 4, B, C, D, E, A);
 97         T_0_15( 5, A, B, C, D, E);
 98         T_0_15( 6, E, A, B, C, D);
 99         T_0_15( 7, D, E, A, B, C);
100         T_0_15( 8, C, D, E, A, B);
101         T_0_15( 9, B, C, D, E, A);
102         T_0_15(10, A, B, C, D, E);
103         T_0_15(11, E, A, B, C, D);
104         T_0_15(12, D, E, A, B, C);
105         T_0_15(13, C, D, E, A, B);
106         T_0_15(14, B, C, D, E, A);
107         T_0_15(15, A, B, C, D, E);
108 
109         /* Round 1 - tail. Input from 512-bit mixing array */
110         T_16_19(16, E, A, B, C, D);
111         T_16_19(17, D, E, A, B, C);
112         T_16_19(18, C, D, E, A, B);
113         T_16_19(19, B, C, D, E, A);
114 
115         /* Round 2 */
116         T_20_39(20, A, B, C, D, E);
117         T_20_39(21, E, A, B, C, D);
118         T_20_39(22, D, E, A, B, C);
119         T_20_39(23, C, D, E, A, B);
120         T_20_39(24, B, C, D, E, A);
121         T_20_39(25, A, B, C, D, E);
122         T_20_39(26, E, A, B, C, D);
123         T_20_39(27, D, E, A, B, C);
124         T_20_39(28, C, D, E, A, B);
125         T_20_39(29, B, C, D, E, A);
126         T_20_39(30, A, B, C, D, E);
127         T_20_39(31, E, A, B, C, D);
128         T_20_39(32, D, E, A, B, C);
129         T_20_39(33, C, D, E, A, B);
130         T_20_39(34, B, C, D, E, A);
131         T_20_39(35, A, B, C, D, E);
132         T_20_39(36, E, A, B, C, D);
133         T_20_39(37, D, E, A, B, C);
134         T_20_39(38, C, D, E, A, B);
135         T_20_39(39, B, C, D, E, A);
136 
137         /* Round 3 */
138         T_40_59(40, A, B, C, D, E);
139         T_40_59(41, E, A, B, C, D);
140         T_40_59(42, D, E, A, B, C);
141         T_40_59(43, C, D, E, A, B);
142         T_40_59(44, B, C, D, E, A);
143         T_40_59(45, A, B, C, D, E);
144         T_40_59(46, E, A, B, C, D);
145         T_40_59(47, D, E, A, B, C);
146         T_40_59(48, C, D, E, A, B);
147         T_40_59(49, B, C, D, E, A);
148         T_40_59(50, A, B, C, D, E);
149         T_40_59(51, E, A, B, C, D);
150         T_40_59(52, D, E, A, B, C);
151         T_40_59(53, C, D, E, A, B);
152         T_40_59(54, B, C, D, E, A);
153         T_40_59(55, A, B, C, D, E);
154         T_40_59(56, E, A, B, C, D);
155         T_40_59(57, D, E, A, B, C);
156         T_40_59(58, C, D, E, A, B);
157         T_40_59(59, B, C, D, E, A);
158 
159         /* Round 4 */
160         T_60_79(60, A, B, C, D, E);
161         T_60_79(61, E, A, B, C, D);
162         T_60_79(62, D, E, A, B, C);
163         T_60_79(63, C, D, E, A, B);
164         T_60_79(64, B, C, D, E, A);
165         T_60_79(65, A, B, C, D, E);
166         T_60_79(66, E, A, B, C, D);
167         T_60_79(67, D, E, A, B, C);
168         T_60_79(68, C, D, E, A, B);
169         T_60_79(69, B, C, D, E, A);
170         T_60_79(70, A, B, C, D, E);
171         T_60_79(71, E, A, B, C, D);
172         T_60_79(72, D, E, A, B, C);
173         T_60_79(73, C, D, E, A, B);
174         T_60_79(74, B, C, D, E, A);
175         T_60_79(75, A, B, C, D, E);
176         T_60_79(76, E, A, B, C, D);
177         T_60_79(77, D, E, A, B, C);
178         T_60_79(78, C, D, E, A, B);
179         T_60_79(79, B, C, D, E, A);
180 
181         digest[0] += A;
182         digest[1] += B;
183         digest[2] += C;
184         digest[3] += D;
185         digest[4] += E;
186 }
187 EXPORT_SYMBOL(sha_transform);
188 
189 /**
190  * sha_init - initialize the vectors for a SHA1 digest
191  * @buf: vector to initialize
192  */
193 void sha_init(__u32 *buf)
194 {
195         buf[0] = 0x67452301;
196         buf[1] = 0xefcdab89;
197         buf[2] = 0x98badcfe;
198         buf[3] = 0x10325476;
199         buf[4] = 0xc3d2e1f0;
200 }
201 EXPORT_SYMBOL(sha_init);
202 

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