Root/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 */
81void 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}
187EXPORT_SYMBOL(sha_transform);
188
189/**
190 * sha_init - initialize the vectors for a SHA1 digest
191 * @buf: vector to initialize
192 */
193void 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

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