root/lib/sha1.c

DEFINITIONS

1. sha_transform
2. sha_init

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * SHA1 routine optimized to do word accesses rather than byte accesses,
   4  * and to avoid unnecessary copies into the context array.
   5  *
   6  * This was based on the git SHA1 implementation.
   7  */
   8 
   9 #include <linux/kernel.h>
  10 #include <linux/export.h>
  11 #include <linux/bitops.h>
  12 #include <linux/cryptohash.h>
  13 #include <asm/unaligned.h>
  14 
  15 /*
  16  * If you have 32 registers or more, the compiler can (and should)
  17  * try to change the array[] accesses into registers. However, on
  18  * machines with less than ~25 registers, that won't really work,
  19  * and at least gcc will make an unholy mess of it.
  20  *
  21  * So to avoid that mess which just slows things down, we force
  22  * the stores to memory to actually happen (we might be better off
  23  * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
  24  * suggested by Artur Skawina - that will also make gcc unable to
  25  * try to do the silly "optimize away loads" part because it won't
  26  * see what the value will be).
  27  *
  28  * Ben Herrenschmidt reports that on PPC, the C version comes close
  29  * to the optimized asm with this (ie on PPC you don't want that
  30  * 'volatile', since there are lots of registers).
  31  *
  32  * On ARM we get the best code generation by forcing a full memory barrier
  33  * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
  34  * the stack frame size simply explode and performance goes down the drain.
  35  */
  36 
  37 #ifdef CONFIG_X86
  38   #define setW(x, val) (*(volatile __u32 *)&W(x) = (val))
  39 #elif defined(CONFIG_ARM)
  40   #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
  41 #else
  42   #define setW(x, val) (W(x) = (val))
  43 #endif
  44 
  45 /* This "rolls" over the 512-bit array */
  46 #define W(x) (array[(x)&15])
  47 
  48 /*
  49  * Where do we get the source from? The first 16 iterations get it from
  50  * the input data, the next mix it from the 512-bit array.
  51  */
  52 #define SHA_SRC(t) get_unaligned_be32((__u32 *)data + t)
  53 #define SHA_MIX(t) rol32(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
  54 
  55 #define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
  56         __u32 TEMP = input(t); setW(t, TEMP); \
  57         E += TEMP + rol32(A,5) + (fn) + (constant); \
  58         B = ror32(B, 2); } while (0)
  59 
  60 #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 )
  61 #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 )
  62 #define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
  63 #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 )
  64 #define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6, A, B, C, D, E )
  65 
  66 /**
  67  * sha_transform - single block SHA1 transform
  68  *
  69  * @digest: 160 bit digest to update
  70  * @data:   512 bits of data to hash
  71  * @array:  16 words of workspace (see note)
  72  *
  73  * This function generates a SHA1 digest for a single 512-bit block.
  74  * Be warned, it does not handle padding and message digest, do not
  75  * confuse it with the full FIPS 180-1 digest algorithm for variable
  76  * length messages.
  77  *
  78  * Note: If the hash is security sensitive, the caller should be sure
  79  * to clear the workspace. This is left to the caller to avoid
  80  * unnecessary clears between chained hashing operations.
  81  */
  82 void sha_transform(__u32 *digest, const char *data, __u32 *array)
  83 {
  84         __u32 A, B, C, D, E;
  85 
  86         A = digest[0];
  87         B = digest[1];
  88         C = digest[2];
  89         D = digest[3];
  90         E = digest[4];
  91 
  92         /* Round 1 - iterations 0-16 take their input from 'data' */
  93         T_0_15( 0, A, B, C, D, E);
  94         T_0_15( 1, E, A, B, C, D);
  95         T_0_15( 2, D, E, A, B, C);
  96         T_0_15( 3, C, D, E, A, B);
  97         T_0_15( 4, B, C, D, E, A);
  98         T_0_15( 5, A, B, C, D, E);
  99         T_0_15( 6, E, A, B, C, D);
 100         T_0_15( 7, D, E, A, B, C);
 101         T_0_15( 8, C, D, E, A, B);
 102         T_0_15( 9, B, C, D, E, A);
 103         T_0_15(10, A, B, C, D, E);
 104         T_0_15(11, E, A, B, C, D);
 105         T_0_15(12, D, E, A, B, C);
 106         T_0_15(13, C, D, E, A, B);
 107         T_0_15(14, B, C, D, E, A);
 108         T_0_15(15, A, B, C, D, E);
 109 
 110         /* Round 1 - tail. Input from 512-bit mixing array */
 111         T_16_19(16, E, A, B, C, D);
 112         T_16_19(17, D, E, A, B, C);
 113         T_16_19(18, C, D, E, A, B);
 114         T_16_19(19, B, C, D, E, A);
 115 
 116         /* Round 2 */
 117         T_20_39(20, A, B, C, D, E);
 118         T_20_39(21, E, A, B, C, D);
 119         T_20_39(22, D, E, A, B, C);
 120         T_20_39(23, C, D, E, A, B);
 121         T_20_39(24, B, C, D, E, A);
 122         T_20_39(25, A, B, C, D, E);
 123         T_20_39(26, E, A, B, C, D);
 124         T_20_39(27, D, E, A, B, C);
 125         T_20_39(28, C, D, E, A, B);
 126         T_20_39(29, B, C, D, E, A);
 127         T_20_39(30, A, B, C, D, E);
 128         T_20_39(31, E, A, B, C, D);
 129         T_20_39(32, D, E, A, B, C);
 130         T_20_39(33, C, D, E, A, B);
 131         T_20_39(34, B, C, D, E, A);
 132         T_20_39(35, A, B, C, D, E);
 133         T_20_39(36, E, A, B, C, D);
 134         T_20_39(37, D, E, A, B, C);
 135         T_20_39(38, C, D, E, A, B);
 136         T_20_39(39, B, C, D, E, A);
 137 
 138         /* Round 3 */
 139         T_40_59(40, A, B, C, D, E);
 140         T_40_59(41, E, A, B, C, D);
 141         T_40_59(42, D, E, A, B, C);
 142         T_40_59(43, C, D, E, A, B);
 143         T_40_59(44, B, C, D, E, A);
 144         T_40_59(45, A, B, C, D, E);
 145         T_40_59(46, E, A, B, C, D);
 146         T_40_59(47, D, E, A, B, C);
 147         T_40_59(48, C, D, E, A, B);
 148         T_40_59(49, B, C, D, E, A);
 149         T_40_59(50, A, B, C, D, E);
 150         T_40_59(51, E, A, B, C, D);
 151         T_40_59(52, D, E, A, B, C);
 152         T_40_59(53, C, D, E, A, B);
 153         T_40_59(54, B, C, D, E, A);
 154         T_40_59(55, A, B, C, D, E);
 155         T_40_59(56, E, A, B, C, D);
 156         T_40_59(57, D, E, A, B, C);
 157         T_40_59(58, C, D, E, A, B);
 158         T_40_59(59, B, C, D, E, A);
 159 
 160         /* Round 4 */
 161         T_60_79(60, A, B, C, D, E);
 162         T_60_79(61, E, A, B, C, D);
 163         T_60_79(62, D, E, A, B, C);
 164         T_60_79(63, C, D, E, A, B);
 165         T_60_79(64, B, C, D, E, A);
 166         T_60_79(65, A, B, C, D, E);
 167         T_60_79(66, E, A, B, C, D);
 168         T_60_79(67, D, E, A, B, C);
 169         T_60_79(68, C, D, E, A, B);
 170         T_60_79(69, B, C, D, E, A);
 171         T_60_79(70, A, B, C, D, E);
 172         T_60_79(71, E, A, B, C, D);
 173         T_60_79(72, D, E, A, B, C);
 174         T_60_79(73, C, D, E, A, B);
 175         T_60_79(74, B, C, D, E, A);
 176         T_60_79(75, A, B, C, D, E);
 177         T_60_79(76, E, A, B, C, D);
 178         T_60_79(77, D, E, A, B, C);
 179         T_60_79(78, C, D, E, A, B);
 180         T_60_79(79, B, C, D, E, A);
 181 
 182         digest[0] += A;
 183         digest[1] += B;
 184         digest[2] += C;
 185         digest[3] += D;
 186         digest[4] += E;
 187 }
 188 EXPORT_SYMBOL(sha_transform);
 189 
 190 /**
 191  * sha_init - initialize the vectors for a SHA1 digest
 192  * @buf: vector to initialize
 193  */
 194 void sha_init(__u32 *buf)
 195 {
 196         buf[0] = 0x67452301;
 197         buf[1] = 0xefcdab89;
 198         buf[2] = 0x98badcfe;
 199         buf[3] = 0x10325476;
 200         buf[4] = 0xc3d2e1f0;
 201 }
 202 EXPORT_SYMBOL(sha_init);