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	sha256.c - sbase - suckless unix tools
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	sha256.c (3600B)
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	1 /* public domain sha256 implementation based on fips180-3 */
	2 #include <ctype.h>
	3 #include <stdint.h>
	4 #include <stdio.h>
	5 #include <stdlib.h>
	6 #include <string.h>
	7
	8 #include "../sha256.h"
	9
	10 static uint32_t ror(uint32_t n, int k) { return (n >> k) \| (n << (32-k))…
	11 #define Ch(x,y,z) (z ^ (x & (y ^ z)))
	12 #define Maj(x,y,z) ((x & y) \| (z & (x \| y)))
	13 #define S0(x) (ror(x,2) ^ ror(x,13) ^ ror(x,22))
	14 #define S1(x) (ror(x,6) ^ ror(x,11) ^ ror(x,25))
	15 #define R0(x) (ror(x,7) ^ ror(x,18) ^ (x>>3))
	16 #define R1(x) (ror(x,17) ^ ror(x,19) ^ (x>>10))
	17
	18 static const uint32_t K[64] = {
	19 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, …
	20 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, …
	21 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, …
	22 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, …
	23 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, …
	24 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, …
	25 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, …
	26 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, …
	27 };
	28
	29 static void
	30 processblock(struct sha256 s, const uint8_t buf)
	31 {
	32 uint32_t W[64], t1, t2, a, b, c, d, e, f, g, h;
	33 int i;
	34
	35 for (i = 0; i < 16; i++) {
	36 W[i] = (uint32_t)buf[4*i]<<24;
	37 W[i] \|= (uint32_t)buf[4*i+1]<<16;
	38 W[i] \|= (uint32_t)buf[4*i+2]<<8;
	39 W[i] \|= buf[4*i+3];
	40 }
	41 for (; i < 64; i++)
	42 W[i] = R1(W[i-2]) + W[i-7] + R0(W[i-15]) + W[i-16];
	43 a = s->h[0];
	44 b = s->h[1];
	45 c = s->h[2];
	46 d = s->h[3];
	47 e = s->h[4];
	48 f = s->h[5];
	49 g = s->h[6];
	50 h = s->h[7];
	51 for (i = 0; i < 64; i++) {
	52 t1 = h + S1(e) + Ch(e,f,g) + K[i] + W[i];
	53 t2 = S0(a) + Maj(a,b,c);
	54 h = g;
	55 g = f;
	56 f = e;
	57 e = d + t1;
	58 d = c;
	59 c = b;
	60 b = a;
	61 a = t1 + t2;
	62 }
	63 s->h[0] += a;
	64 s->h[1] += b;
	65 s->h[2] += c;
	66 s->h[3] += d;
	67 s->h[4] += e;
	68 s->h[5] += f;
	69 s->h[6] += g;
	70 s->h[7] += h;
	71 }
	72
	73 static void
	74 pad(struct sha256 *s)
	75 {
	76 unsigned r = s->len % 64;
	77
	78 s->buf[r++] = 0x80;
	79 if (r > 56) {
	80 memset(s->buf + r, 0, 64 - r);
	81 r = 0;
	82 processblock(s, s->buf);
	83 }
	84 memset(s->buf + r, 0, 56 - r);
	85 s->len *= 8;
	86 s->buf[56] = s->len >> 56;
	87 s->buf[57] = s->len >> 48;
	88 s->buf[58] = s->len >> 40;
	89 s->buf[59] = s->len >> 32;
	90 s->buf[60] = s->len >> 24;
	91 s->buf[61] = s->len >> 16;
	92 s->buf[62] = s->len >> 8;
	93 s->buf[63] = s->len;
	94 processblock(s, s->buf);
	95 }
	96
	97 void
	98 sha256_init(void *ctx)
	99 {
	100 struct sha256 *s = ctx;
	101 s->len = 0;
	102 s->h[0] = 0x6a09e667;
	103 s->h[1] = 0xbb67ae85;
	104 s->h[2] = 0x3c6ef372;
	105 s->h[3] = 0xa54ff53a;
	106 s->h[4] = 0x510e527f;
	107 s->h[5] = 0x9b05688c;
	108 s->h[6] = 0x1f83d9ab;
	109 s->h[7] = 0x5be0cd19;
	110 }
	111
	112 void
	113 sha256_sum_n(void ctx, uint8_t md, int n)
	114 {
	115 struct sha256 *s = ctx;
	116 int i;
	117
	118 pad(s);
	119 for (i = 0; i < n; i++) {
	120 md[4*i] = s->h[i] >> 24;
	121 md[4*i+1] = s->h[i] >> 16;
	122 md[4*i+2] = s->h[i] >> 8;
	123 md[4*i+3] = s->h[i];
	124 }
	125 }
	126
	127 void
	128 sha256_sum(void *ctx, uint8_t md[SHA256_DIGEST_LENGTH])
	129 {
	130 sha256_sum_n(ctx, md, 8);
	131 }
	132
	133 void
	134 sha256_update(void ctx, const void m, unsigned long len)
	135 {
	136 struct sha256 *s = ctx;
	137 const uint8_t *p = m;
	138 unsigned r = s->len % 64;
	139
	140 s->len += len;
	141 if (r) {
	142 if (len < 64 - r) {
	143 memcpy(s->buf + r, p, len);
	144 return;
	145 }
	146 memcpy(s->buf + r, p, 64 - r);
	147 len -= 64 - r;
	148 p += 64 - r;
	149 processblock(s, s->buf);
	150 }
	151 for (; len >= 64; len -= 64, p += 64)
	152 processblock(s, p);
	153 memcpy(s->buf, p, len);
	154 }