linux/lib/sha1.c
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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 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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