Andrew's git - gitweb.git/blob

   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#if defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
  15
  16/*
  17 * Force usage of rol or ror by selecting the one with the smaller constant.
  18 * It _can_ generate slightly smaller code (a constant of 1 is special), but
  19 * perhaps more importantly it's possibly faster on any uarch that does a
  20 * rotate with a loop.
  21 */
  22
  23#define SHA_ASM(op, x, n) ({ unsigned int __res; __asm__(op " %1,%0":"=r" (__res):"i" (n), "0" (x)); __res; })
  24#define SHA_ROL(x,n)    SHA_ASM("rol", x, n)
  25#define SHA_ROR(x,n)    SHA_ASM("ror", x, n)
  26
  27#else
  28
  29#define SHA_ROT(X,l,r)  (((X) << (l)) | ((X) >> (r)))
  30#define SHA_ROL(X,n)    SHA_ROT(X,n,32-(n))
  31#define SHA_ROR(X,n)    SHA_ROT(X,32-(n),n)
  32
  33#endif
  34
  35/*
  36 * If you have 32 registers or more, the compiler can (and should)
  37 * try to change the array[] accesses into registers. However, on
  38 * machines with less than ~25 registers, that won't really work,
  39 * and at least gcc will make an unholy mess of it.
  40 *
  41 * So to avoid that mess which just slows things down, we force
  42 * the stores to memory to actually happen (we might be better off
  43 * with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
  44 * suggested by Artur Skawina - that will also make gcc unable to
  45 * try to do the silly "optimize away loads" part because it won't
  46 * see what the value will be).
  47 *
  48 * Ben Herrenschmidt reports that on PPC, the C version comes close
  49 * to the optimized asm with this (ie on PPC you don't want that
  50 * 'volatile', since there are lots of registers).
  51 *
  52 * On ARM we get the best code generation by forcing a full memory barrier
  53 * between each SHA_ROUND, otherwise gcc happily get wild with spilling and
  54 * the stack frame size simply explode and performance goes down the drain.
  55 */
  56
  57#if defined(__i386__) || defined(__x86_64__)
  58  #define setW(x, val) (*(volatile unsigned int *)&W(x) = (val))
  59#elif defined(__GNUC__) && defined(__arm__)
  60  #define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)
  61#else
  62  #define setW(x, val) (W(x) = (val))
  63#endif
  64
  65/*
  66 * Performance might be improved if the CPU architecture is OK with
  67 * unaligned 32-bit loads and a fast ntohl() is available.
  68 * Otherwise fall back to byte loads and shifts which is portable,
  69 * and is faster on architectures with memory alignment issues.
  70 */
  71
  72#if defined(__i386__) || defined(__x86_64__) || \
  73    defined(__ppc__) || defined(__ppc64__) || \
  74    defined(__powerpc__) || defined(__powerpc64__) || \
  75    defined(__s390__) || defined(__s390x__)
  76
  77#define get_be32(p)     ntohl(*(unsigned int *)(p))
  78#define put_be32(p, v)  do { *(unsigned int *)(p) = htonl(v); } while (0)
  79
  80#else
  81
  82#define get_be32(p)     ( \
  83        (*((unsigned char *)(p) + 0) << 24) | \
  84        (*((unsigned char *)(p) + 1) << 16) | \
  85        (*((unsigned char *)(p) + 2) <<  8) | \
  86        (*((unsigned char *)(p) + 3) <<  0) )
  87#define put_be32(p, v)  do { \
  88        unsigned int __v = (v); \
  89        *((unsigned char *)(p) + 0) = __v >> 24; \
  90        *((unsigned char *)(p) + 1) = __v >> 16; \
  91        *((unsigned char *)(p) + 2) = __v >>  8; \
  92        *((unsigned char *)(p) + 3) = __v >>  0; } while (0)
  93
  94#endif
  95
  96/* This "rolls" over the 512-bit array */
  97#define W(x) (array[(x)&15])
  98
  99/*
 100 * Where do we get the source from? The first 16 iterations get it from
 101 * the input data, the next mix it from the 512-bit array.
 102 */
 103#define SHA_SRC(t) get_be32(data + t)
 104#define SHA_MIX(t) SHA_ROL(W(t+13) ^ W(t+8) ^ W(t+2) ^ W(t), 1)
 105
 106#define SHA_ROUND(t, input, fn, constant, A, B, C, D, E) do { \
 107        unsigned int TEMP = input(t); setW(t, TEMP); \
 108        E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \
 109        B = SHA_ROR(B, 2); } while (0)
 110
 111#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 )
 112#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 )
 113#define T_20_39(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) , 0x6ed9eba1, A, B, C, D, E )
 114#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 )
 115#define T_60_79(t, A, B, C, D, E) SHA_ROUND(t, SHA_MIX, (B^C^D) ,  0xca62c1d6, A, B, C, D, E )
 116
 117static void blk_SHA1_Block(blk_SHA_CTX *ctx, const unsigned int *data)
 118{
 119        unsigned int A,B,C,D,E;
 120        unsigned int array[16];
 121
 122        A = ctx->H[0];
 123        B = ctx->H[1];
 124        C = ctx->H[2];
 125        D = ctx->H[3];
 126        E = ctx->H[4];
 127
 128        /* Round 1 - iterations 0-16 take their input from 'data' */
 129        T_0_15( 0, A, B, C, D, E);
 130        T_0_15( 1, E, A, B, C, D);
 131        T_0_15( 2, D, E, A, B, C);
 132        T_0_15( 3, C, D, E, A, B);
 133        T_0_15( 4, B, C, D, E, A);
 134        T_0_15( 5, A, B, C, D, E);
 135        T_0_15( 6, E, A, B, C, D);
 136        T_0_15( 7, D, E, A, B, C);
 137        T_0_15( 8, C, D, E, A, B);
 138        T_0_15( 9, B, C, D, E, A);
 139        T_0_15(10, A, B, C, D, E);
 140        T_0_15(11, E, A, B, C, D);
 141        T_0_15(12, D, E, A, B, C);
 142        T_0_15(13, C, D, E, A, B);
 143        T_0_15(14, B, C, D, E, A);
 144        T_0_15(15, A, B, C, D, E);
 145
 146        /* Round 1 - tail. Input from 512-bit mixing array */
 147        T_16_19(16, E, A, B, C, D);
 148        T_16_19(17, D, E, A, B, C);
 149        T_16_19(18, C, D, E, A, B);
 150        T_16_19(19, B, C, D, E, A);
 151
 152        /* Round 2 */
 153        T_20_39(20, A, B, C, D, E);
 154        T_20_39(21, E, A, B, C, D);
 155        T_20_39(22, D, E, A, B, C);
 156        T_20_39(23, C, D, E, A, B);
 157        T_20_39(24, B, C, D, E, A);
 158        T_20_39(25, A, B, C, D, E);
 159        T_20_39(26, E, A, B, C, D);
 160        T_20_39(27, D, E, A, B, C);
 161        T_20_39(28, C, D, E, A, B);
 162        T_20_39(29, B, C, D, E, A);
 163        T_20_39(30, A, B, C, D, E);
 164        T_20_39(31, E, A, B, C, D);
 165        T_20_39(32, D, E, A, B, C);
 166        T_20_39(33, C, D, E, A, B);
 167        T_20_39(34, B, C, D, E, A);
 168        T_20_39(35, A, B, C, D, E);
 169        T_20_39(36, E, A, B, C, D);
 170        T_20_39(37, D, E, A, B, C);
 171        T_20_39(38, C, D, E, A, B);
 172        T_20_39(39, B, C, D, E, A);
 173
 174        /* Round 3 */
 175        T_40_59(40, A, B, C, D, E);
 176        T_40_59(41, E, A, B, C, D);
 177        T_40_59(42, D, E, A, B, C);
 178        T_40_59(43, C, D, E, A, B);
 179        T_40_59(44, B, C, D, E, A);
 180        T_40_59(45, A, B, C, D, E);
 181        T_40_59(46, E, A, B, C, D);
 182        T_40_59(47, D, E, A, B, C);
 183        T_40_59(48, C, D, E, A, B);
 184        T_40_59(49, B, C, D, E, A);
 185        T_40_59(50, A, B, C, D, E);
 186        T_40_59(51, E, A, B, C, D);
 187        T_40_59(52, D, E, A, B, C);
 188        T_40_59(53, C, D, E, A, B);
 189        T_40_59(54, B, C, D, E, A);
 190        T_40_59(55, A, B, C, D, E);
 191        T_40_59(56, E, A, B, C, D);
 192        T_40_59(57, D, E, A, B, C);
 193        T_40_59(58, C, D, E, A, B);
 194        T_40_59(59, B, C, D, E, A);
 195
 196        /* Round 4 */
 197        T_60_79(60, A, B, C, D, E);
 198        T_60_79(61, E, A, B, C, D);
 199        T_60_79(62, D, E, A, B, C);
 200        T_60_79(63, C, D, E, A, B);
 201        T_60_79(64, B, C, D, E, A);
 202        T_60_79(65, A, B, C, D, E);
 203        T_60_79(66, E, A, B, C, D);
 204        T_60_79(67, D, E, A, B, C);
 205        T_60_79(68, C, D, E, A, B);
 206        T_60_79(69, B, C, D, E, A);
 207        T_60_79(70, A, B, C, D, E);
 208        T_60_79(71, E, A, B, C, D);
 209        T_60_79(72, D, E, A, B, C);
 210        T_60_79(73, C, D, E, A, B);
 211        T_60_79(74, B, C, D, E, A);
 212        T_60_79(75, A, B, C, D, E);
 213        T_60_79(76, E, A, B, C, D);
 214        T_60_79(77, D, E, A, B, C);
 215        T_60_79(78, C, D, E, A, B);
 216        T_60_79(79, B, C, D, E, A);
 217
 218        ctx->H[0] += A;
 219        ctx->H[1] += B;
 220        ctx->H[2] += C;
 221        ctx->H[3] += D;
 222        ctx->H[4] += E;
 223}
 224
 225void blk_SHA1_Init(blk_SHA_CTX *ctx)
 226{
 227        ctx->size = 0;
 228
 229        /* Initialize H with the magic constants (see FIPS180 for constants) */
 230        ctx->H[0] = 0x67452301;
 231        ctx->H[1] = 0xefcdab89;
 232        ctx->H[2] = 0x98badcfe;
 233        ctx->H[3] = 0x10325476;
 234        ctx->H[4] = 0xc3d2e1f0;
 235}
 236
 237void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, unsigned long len)
 238{
 239        int lenW = ctx->size & 63;
 240
 241        ctx->size += len;
 242
 243        /* Read the data into W and process blocks as they get full */
 244        if (lenW) {
 245                int left = 64 - lenW;
 246                if (len < left)
 247                        left = len;
 248                memcpy(lenW + (char *)ctx->W, data, left);
 249                lenW = (lenW + left) & 63;
 250                len -= left;
 251                data = ((const char *)data + left);
 252                if (lenW)
 253                        return;
 254                blk_SHA1_Block(ctx, ctx->W);
 255        }
 256        while (len >= 64) {
 257                blk_SHA1_Block(ctx, data);
 258                data = ((const char *)data + 64);
 259                len -= 64;
 260        }
 261        if (len)
 262                memcpy(ctx->W, data, len);
 263}
 264
 265void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)
 266{
 267        static const unsigned char pad[64] = { 0x80 };
 268        unsigned int padlen[2];
 269        int i;
 270
 271        /* Pad with a binary 1 (ie 0x80), then zeroes, then length */
 272        padlen[0] = htonl(ctx->size >> 29);
 273        padlen[1] = htonl(ctx->size << 3);
 274
 275        i = ctx->size & 63;
 276        blk_SHA1_Update(ctx, pad, 1+ (63 & (55 - i)));
 277        blk_SHA1_Update(ctx, padlen, 8);
 278
 279        /* Output hash */
 280        for (i = 0; i < 5; i++)
 281                put_be32(hashout + i*4, ctx->H[i]);
 282}