sha256.c (5339B)
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 <string.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 uint32_t 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 uint8_t data[]) { 45 uint32_t a, b, c, d, e, f, g, h, i, j, t1, t2, m[64]; 46 47 for (i = 0, j = 0; i < 16; ++i, j += 4) 48 m[i] = ((uint32_t)data[j] << 24) | 49 ((uint32_t)data[j + 1] << 16) | 50 ((uint32_t)data[j + 2] << 8) | 51 ((uint32_t)data[j + 3]); 52 for ( ; i < 64; ++i) 53 m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16]; 54 55 a = ctx->state[0]; 56 b = ctx->state[1]; 57 c = ctx->state[2]; 58 d = ctx->state[3]; 59 e = ctx->state[4]; 60 f = ctx->state[5]; 61 g = ctx->state[6]; 62 h = ctx->state[7]; 63 64 for (i = 0; i < 64; ++i) { 65 t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i]; 66 t2 = EP0(a) + MAJ(a,b,c); 67 h = g; 68 g = f; 69 f = e; 70 e = d + t1; 71 d = c; 72 c = b; 73 b = a; 74 a = t1 + t2; 75 } 76 77 ctx->state[0] += a; 78 ctx->state[1] += b; 79 ctx->state[2] += c; 80 ctx->state[3] += d; 81 ctx->state[4] += e; 82 ctx->state[5] += f; 83 ctx->state[6] += g; 84 ctx->state[7] += h; 85 } 86 87 void sha256_init(SHA256_CTX *ctx) { 88 ctx->datalen = 0; 89 ctx->bitlen = 0; 90 ctx->state[0] = 0x6a09e667; 91 ctx->state[1] = 0xbb67ae85; 92 ctx->state[2] = 0x3c6ef372; 93 ctx->state[3] = 0xa54ff53a; 94 ctx->state[4] = 0x510e527f; 95 ctx->state[5] = 0x9b05688c; 96 ctx->state[6] = 0x1f83d9ab; 97 ctx->state[7] = 0x5be0cd19; 98 } 99 100 void sha256_update(SHA256_CTX *ctx, const uint8_t data[], size_t len) { 101 uint32_t 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, uint8_t hash[]) { 115 uint32_t i; 116 117 i = ctx->datalen; 118 119 // Pad whatever data is left in the buffer. 120 if (ctx->datalen < 56) { 121 ctx->data[i++] = 0x80; 122 while (i < 56) 123 ctx->data[i++] = 0x00; 124 } 125 else { 126 ctx->data[i++] = 0x80; 127 while (i < 64) 128 ctx->data[i++] = 0x00; 129 sha256_transform(ctx, ctx->data); 130 memset(ctx->data, 0, 56); 131 } 132 133 // Append to the padding the total message's length in bits and transform. 134 ctx->bitlen += ctx->datalen * 8; 135 ctx->data[63] = ctx->bitlen; 136 ctx->data[62] = ctx->bitlen >> 8; 137 ctx->data[61] = ctx->bitlen >> 16; 138 ctx->data[60] = ctx->bitlen >> 24; 139 ctx->data[59] = ctx->bitlen >> 32; 140 ctx->data[58] = ctx->bitlen >> 40; 141 ctx->data[57] = ctx->bitlen >> 48; 142 ctx->data[56] = ctx->bitlen >> 56; 143 sha256_transform(ctx, ctx->data); 144 145 // Since this implementation uses little endian byte ordering and SHA uses big endian, 146 // reverse all the bytes when copying the final state to the output hash. 147 for (i = 0; i < 4; ++i) { 148 hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff; 149 hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff; 150 hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff; 151 hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff; 152 hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff; 153 hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff; 154 hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff; 155 hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff; 156 } 157 }