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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 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#define SHA_ROT(X,l,r) (((X) << (l)) | ((X) >> (r)))15#define SHA_ROL(X,n) SHA_ROT(X,n,32-(n))16#define SHA_ROR(X,n) SHA_ROT(X,32-(n),n)17
18/*
19* If you have 32 registers or more, the compiler can (and should)
20* try to change the array[] accesses into registers. However, on
21* machines with less than ~25 registers, that won't really work,
22* and at least gcc will make an unholy mess of it.
23*
24* So to avoid that mess which just slows things down, we force
25* the stores to memory to actually happen (we might be better off
26* with a 'W(t)=(val);asm("":"+m" (W(t))' there instead, as
27* suggested by Artur Skawina - that will also make gcc unable to
28* try to do the silly "optimize away loads" part because it won't
29* see what the value will be).
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#if defined(__i386__) || defined(__x86_64__)37#define setW(x, val) (*(volatile unsigned int *)&W(x) = (val))38#elif defined(__GNUC__) && defined(__arm__)39#define setW(x, val) do { W(x) = (val); __asm__("":::"memory"); } while (0)40#else41#define setW(x, val) (W(x) = (val))42#endif43
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_be32((unsigned char *) block + (t)*4)52#define SHA_MIX(t) SHA_ROL(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 { \55unsigned int TEMP = input(t); setW(t, TEMP); \56E += TEMP + SHA_ROL(A,5) + (fn) + (constant); \57B = SHA_ROR(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
65static void blk_SHA1_Block(blk_SHA_CTX *ctx, const void *block)66{
67unsigned int A,B,C,D,E;68unsigned int array[16];69
70A = ctx->H[0];71B = ctx->H[1];72C = ctx->H[2];73D = ctx->H[3];74E = ctx->H[4];75
76/* Round 1 - iterations 0-16 take their input from 'block' */77T_0_15( 0, A, B, C, D, E);78T_0_15( 1, E, A, B, C, D);79T_0_15( 2, D, E, A, B, C);80T_0_15( 3, C, D, E, A, B);81T_0_15( 4, B, C, D, E, A);82T_0_15( 5, A, B, C, D, E);83T_0_15( 6, E, A, B, C, D);84T_0_15( 7, D, E, A, B, C);85T_0_15( 8, C, D, E, A, B);86T_0_15( 9, B, C, D, E, A);87T_0_15(10, A, B, C, D, E);88T_0_15(11, E, A, B, C, D);89T_0_15(12, D, E, A, B, C);90T_0_15(13, C, D, E, A, B);91T_0_15(14, B, C, D, E, A);92T_0_15(15, A, B, C, D, E);93
94/* Round 1 - tail. Input from 512-bit mixing array */95T_16_19(16, E, A, B, C, D);96T_16_19(17, D, E, A, B, C);97T_16_19(18, C, D, E, A, B);98T_16_19(19, B, C, D, E, A);99
100/* Round 2 */101T_20_39(20, A, B, C, D, E);102T_20_39(21, E, A, B, C, D);103T_20_39(22, D, E, A, B, C);104T_20_39(23, C, D, E, A, B);105T_20_39(24, B, C, D, E, A);106T_20_39(25, A, B, C, D, E);107T_20_39(26, E, A, B, C, D);108T_20_39(27, D, E, A, B, C);109T_20_39(28, C, D, E, A, B);110T_20_39(29, B, C, D, E, A);111T_20_39(30, A, B, C, D, E);112T_20_39(31, E, A, B, C, D);113T_20_39(32, D, E, A, B, C);114T_20_39(33, C, D, E, A, B);115T_20_39(34, B, C, D, E, A);116T_20_39(35, A, B, C, D, E);117T_20_39(36, E, A, B, C, D);118T_20_39(37, D, E, A, B, C);119T_20_39(38, C, D, E, A, B);120T_20_39(39, B, C, D, E, A);121
122/* Round 3 */123T_40_59(40, A, B, C, D, E);124T_40_59(41, E, A, B, C, D);125T_40_59(42, D, E, A, B, C);126T_40_59(43, C, D, E, A, B);127T_40_59(44, B, C, D, E, A);128T_40_59(45, A, B, C, D, E);129T_40_59(46, E, A, B, C, D);130T_40_59(47, D, E, A, B, C);131T_40_59(48, C, D, E, A, B);132T_40_59(49, B, C, D, E, A);133T_40_59(50, A, B, C, D, E);134T_40_59(51, E, A, B, C, D);135T_40_59(52, D, E, A, B, C);136T_40_59(53, C, D, E, A, B);137T_40_59(54, B, C, D, E, A);138T_40_59(55, A, B, C, D, E);139T_40_59(56, E, A, B, C, D);140T_40_59(57, D, E, A, B, C);141T_40_59(58, C, D, E, A, B);142T_40_59(59, B, C, D, E, A);143
144/* Round 4 */145T_60_79(60, A, B, C, D, E);146T_60_79(61, E, A, B, C, D);147T_60_79(62, D, E, A, B, C);148T_60_79(63, C, D, E, A, B);149T_60_79(64, B, C, D, E, A);150T_60_79(65, A, B, C, D, E);151T_60_79(66, E, A, B, C, D);152T_60_79(67, D, E, A, B, C);153T_60_79(68, C, D, E, A, B);154T_60_79(69, B, C, D, E, A);155T_60_79(70, A, B, C, D, E);156T_60_79(71, E, A, B, C, D);157T_60_79(72, D, E, A, B, C);158T_60_79(73, C, D, E, A, B);159T_60_79(74, B, C, D, E, A);160T_60_79(75, A, B, C, D, E);161T_60_79(76, E, A, B, C, D);162T_60_79(77, D, E, A, B, C);163T_60_79(78, C, D, E, A, B);164T_60_79(79, B, C, D, E, A);165
166ctx->H[0] += A;167ctx->H[1] += B;168ctx->H[2] += C;169ctx->H[3] += D;170ctx->H[4] += E;171}
172
173void blk_SHA1_Init(blk_SHA_CTX *ctx)174{
175ctx->size = 0;176
177/* Initialize H with the magic constants (see FIPS180 for constants) */178ctx->H[0] = 0x67452301;179ctx->H[1] = 0xefcdab89;180ctx->H[2] = 0x98badcfe;181ctx->H[3] = 0x10325476;182ctx->H[4] = 0xc3d2e1f0;183}
184
185void blk_SHA1_Update(blk_SHA_CTX *ctx, const void *data, size_t len)186{
187unsigned int lenW = ctx->size & 63;188
189ctx->size += len;190
191/* Read the data into W and process blocks as they get full */192if (lenW) {193unsigned int left = 64 - lenW;194if (len < left)195left = len;196memcpy(lenW + (char *)ctx->W, data, left);197lenW = (lenW + left) & 63;198len -= left;199data = ((const char *)data + left);200if (lenW)201return;202blk_SHA1_Block(ctx, ctx->W);203}204while (len >= 64) {205blk_SHA1_Block(ctx, data);206data = ((const char *)data + 64);207len -= 64;208}209if (len)210memcpy(ctx->W, data, len);211}
212
213void blk_SHA1_Final(unsigned char hashout[20], blk_SHA_CTX *ctx)214{
215static const unsigned char pad[64] = { 0x80 };216unsigned int padlen[2];217int i;218
219/* Pad with a binary 1 (ie 0x80), then zeroes, then length */220padlen[0] = htonl((uint32_t)(ctx->size >> 29));221padlen[1] = htonl((uint32_t)(ctx->size << 3));222
223i = ctx->size & 63;224blk_SHA1_Update(ctx, pad, 1 + (63 & (55 - i)));225blk_SHA1_Update(ctx, padlen, 8);226
227/* Output hash */228for (i = 0; i < 5; i++)229put_be32(hashout + i * 4, ctx->H[i]);230}
231