sha256

Simple C SHA256 implementation. Author: Brad Conte
git clone https://noulin.net/git/sha256.git
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bconSha256.c (5263B)


      1 /*********************************************************************
      2 * Filename:   sha256.c
      3 * Author:     Brad Conte (brad AT bradconte.com)
      4 * Copyright:
      5 * Disclaimer: This code is presented "as is" without any guarantees.
      6 * Details:    Implementation of the SHA-256 hashing algorithm.
      7               SHA-256 is one of the three algorithms in the SHA2
      8               specification. The others, SHA-384 and SHA-512, are not
      9               offered in this implementation.
     10               Algorithm specification can be found here:
     11                * http://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf
     12               This implementation uses little endian byte order.
     13 *********************************************************************/
     14 
     15 /*************************** HEADER FILES ***************************/
     16 #include <stdlib.h>
     17 #include <memory.h>
     18 #include "sha256.h"
     19 
     20 /****************************** MACROS ******************************/
     21 #define ROTLEFT(a,b) (((a) << (b)) | ((a) >> (32-(b))))
     22 #define ROTRIGHT(a,b) (((a) >> (b)) | ((a) << (32-(b))))
     23 
     24 #define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z)))
     25 #define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
     26 #define EP0(x) (ROTRIGHT(x,2) ^ ROTRIGHT(x,13) ^ ROTRIGHT(x,22))
     27 #define EP1(x) (ROTRIGHT(x,6) ^ ROTRIGHT(x,11) ^ ROTRIGHT(x,25))
     28 #define SIG0(x) (ROTRIGHT(x,7) ^ ROTRIGHT(x,18) ^ ((x) >> 3))
     29 #define SIG1(x) (ROTRIGHT(x,17) ^ ROTRIGHT(x,19) ^ ((x) >> 10))
     30 
     31 /**************************** VARIABLES *****************************/
     32 static const WORD k[64] = {
     33 	0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
     34 	0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
     35 	0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
     36 	0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
     37 	0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
     38 	0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
     39 	0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
     40 	0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2
     41 };
     42 
     43 /*********************** FUNCTION DEFINITIONS ***********************/
     44 void sha256_transform(SHA256_CTX *ctx, const BYTE data[])
     45 {
     46 	WORD a, b, c, d, e, f, g, h, i, j, t1, t2, m[64];
     47 
     48 	for (i = 0, j = 0; i < 16; ++i, j += 4)
     49 		m[i] = (data[j] << 24) | (data[j + 1] << 16) | (data[j + 2] << 8) | (data[j + 3]);
     50 	for ( ; i < 64; ++i)
     51 		m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16];
     52 
     53 	a = ctx->state[0];
     54 	b = ctx->state[1];
     55 	c = ctx->state[2];
     56 	d = ctx->state[3];
     57 	e = ctx->state[4];
     58 	f = ctx->state[5];
     59 	g = ctx->state[6];
     60 	h = ctx->state[7];
     61 
     62 	for (i = 0; i < 64; ++i) {
     63 		t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i];
     64 		t2 = EP0(a) + MAJ(a,b,c);
     65 		h = g;
     66 		g = f;
     67 		f = e;
     68 		e = d + t1;
     69 		d = c;
     70 		c = b;
     71 		b = a;
     72 		a = t1 + t2;
     73 	}
     74 
     75 	ctx->state[0] += a;
     76 	ctx->state[1] += b;
     77 	ctx->state[2] += c;
     78 	ctx->state[3] += d;
     79 	ctx->state[4] += e;
     80 	ctx->state[5] += f;
     81 	ctx->state[6] += g;
     82 	ctx->state[7] += h;
     83 }
     84 
     85 void sha256_init(SHA256_CTX *ctx)
     86 {
     87 	ctx->datalen = 0;
     88 	ctx->bitlen = 0;
     89 	ctx->state[0] = 0x6a09e667;
     90 	ctx->state[1] = 0xbb67ae85;
     91 	ctx->state[2] = 0x3c6ef372;
     92 	ctx->state[3] = 0xa54ff53a;
     93 	ctx->state[4] = 0x510e527f;
     94 	ctx->state[5] = 0x9b05688c;
     95 	ctx->state[6] = 0x1f83d9ab;
     96 	ctx->state[7] = 0x5be0cd19;
     97 }
     98 
     99 void sha256_update(SHA256_CTX *ctx, const BYTE data[], size_t len)
    100 {
    101 	WORD i;
    102 
    103 	for (i = 0; i < len; ++i) {
    104 		ctx->data[ctx->datalen] = data[i];
    105 		ctx->datalen++;
    106 		if (ctx->datalen == 64) {
    107 			sha256_transform(ctx, ctx->data);
    108 			ctx->bitlen += 512;
    109 			ctx->datalen = 0;
    110 		}
    111 	}
    112 }
    113 
    114 void sha256_final(SHA256_CTX *ctx, BYTE hash[])
    115 {
    116 	WORD i;
    117 
    118 	i = ctx->datalen;
    119 
    120 	// Pad whatever data is left in the buffer.
    121 	if (ctx->datalen < 56) {
    122 		ctx->data[i++] = 0x80;
    123 		while (i < 56)
    124 			ctx->data[i++] = 0x00;
    125 	}
    126 	else {
    127 		ctx->data[i++] = 0x80;
    128 		while (i < 64)
    129 			ctx->data[i++] = 0x00;
    130 		sha256_transform(ctx, ctx->data);
    131 		memset(ctx->data, 0, 56);
    132 	}
    133 
    134 	// Append to the padding the total message's length in bits and transform.
    135 	ctx->bitlen += ctx->datalen * 8;
    136 	ctx->data[63] = ctx->bitlen;
    137 	ctx->data[62] = ctx->bitlen >> 8;
    138 	ctx->data[61] = ctx->bitlen >> 16;
    139 	ctx->data[60] = ctx->bitlen >> 24;
    140 	ctx->data[59] = ctx->bitlen >> 32;
    141 	ctx->data[58] = ctx->bitlen >> 40;
    142 	ctx->data[57] = ctx->bitlen >> 48;
    143 	ctx->data[56] = ctx->bitlen >> 56;
    144 	sha256_transform(ctx, ctx->data);
    145 
    146 	// Since this implementation uses little endian byte ordering and SHA uses big endian,
    147 	// reverse all the bytes when copying the final state to the output hash.
    148 	for (i = 0; i < 4; ++i) {
    149 		hash[i]      = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff;
    150 		hash[i + 4]  = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff;
    151 		hash[i + 8]  = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff;
    152 		hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff;
    153 		hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff;
    154 		hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff;
    155 		hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff;
    156 		hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff;
    157 	}
    158 }