sha256.c
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     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 }