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 <stdint.h>
17 #include <stdlib.h>
18 #include <string.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 #define SHA256_BLOCK_SIZE 32 /* SHA256 outputs a 32 byte digest */
31
32 /**************************** DATA TYPES ****************************/
33 typedef unsigned char BYTE; /* 8-bit byte */
34 typedef unsigned int WORD; /* 32-bit word, change to "long" for 16-bit machines */
35
36 typedef struct {
37 BYTE data[64];
38 WORD datalen;
39 uint64_t bitlen;
40 WORD state[8];
41 } SHA256_CTX;
42
43 /**************************** VARIABLES *****************************/
44 static const WORD k[64] = {
45 0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
46 0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
47 0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
48 0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
49 0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
50 0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
51 0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
52 0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2
53 };
54
55 /*********************** FUNCTION DEFINITIONS ***********************/
sha256_transform(SHA256_CTX * ctx,const BYTE data[])56 void sha256_transform(SHA256_CTX *ctx, const BYTE data[])
57 {
58 WORD a, b, c, d, e, f, g, h, i, j, t1, t2, m[64];
59
60 for (i = 0, j = 0; i < 16; ++i, j += 4)
61 m[i] = (data[j] << 24) | (data[j + 1] << 16) | (data[j + 2] << 8) | (data[j + 3]);
62 for ( ; i < 64; ++i)
63 m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16];
64
65 a = ctx->state[0];
66 b = ctx->state[1];
67 c = ctx->state[2];
68 d = ctx->state[3];
69 e = ctx->state[4];
70 f = ctx->state[5];
71 g = ctx->state[6];
72 h = ctx->state[7];
73
74 for (i = 0; i < 64; ++i) {
75 t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i];
76 t2 = EP0(a) + MAJ(a,b,c);
77 h = g;
78 g = f;
79 f = e;
80 e = d + t1;
81 d = c;
82 c = b;
83 b = a;
84 a = t1 + t2;
85 }
86
87 ctx->state[0] += a;
88 ctx->state[1] += b;
89 ctx->state[2] += c;
90 ctx->state[3] += d;
91 ctx->state[4] += e;
92 ctx->state[5] += f;
93 ctx->state[6] += g;
94 ctx->state[7] += h;
95 }
96
sha256_init(SHA256_CTX * ctx)97 void sha256_init(SHA256_CTX *ctx)
98 {
99 ctx->datalen = 0;
100 ctx->bitlen = 0;
101 ctx->state[0] = 0x6a09e667;
102 ctx->state[1] = 0xbb67ae85;
103 ctx->state[2] = 0x3c6ef372;
104 ctx->state[3] = 0xa54ff53a;
105 ctx->state[4] = 0x510e527f;
106 ctx->state[5] = 0x9b05688c;
107 ctx->state[6] = 0x1f83d9ab;
108 ctx->state[7] = 0x5be0cd19;
109 }
110
sha256_update(SHA256_CTX * ctx,const BYTE data[],size_t len)111 void sha256_update(SHA256_CTX *ctx, const BYTE data[], size_t len)
112 {
113 WORD i;
114
115 for (i = 0; i < len; ++i) {
116 ctx->data[ctx->datalen] = data[i];
117 ctx->datalen++;
118 if (ctx->datalen == 64) {
119 sha256_transform(ctx, ctx->data);
120 ctx->bitlen += 512;
121 ctx->datalen = 0;
122 }
123 }
124 }
125
sha256_final(SHA256_CTX * ctx,BYTE hash[])126 void sha256_final(SHA256_CTX *ctx, BYTE hash[])
127 {
128 WORD i;
129
130 i = ctx->datalen;
131
132 // Pad whatever data is left in the buffer.
133 if (ctx->datalen < 56) {
134 ctx->data[i++] = 0x80;
135 while (i < 56)
136 ctx->data[i++] = 0x00;
137 }
138 else {
139 ctx->data[i++] = 0x80;
140 while (i < 64)
141 ctx->data[i++] = 0x00;
142 sha256_transform(ctx, ctx->data);
143 memset(ctx->data, 0, 56);
144 }
145
146 /* Append to the padding the total message's length in bits and transform. */
147 ctx->bitlen += ctx->datalen * 8;
148 ctx->data[63] = ctx->bitlen;
149 ctx->data[62] = ctx->bitlen >> 8;
150 ctx->data[61] = ctx->bitlen >> 16;
151 ctx->data[60] = ctx->bitlen >> 24;
152 ctx->data[59] = ctx->bitlen >> 32;
153 ctx->data[58] = ctx->bitlen >> 40;
154 ctx->data[57] = ctx->bitlen >> 48;
155 ctx->data[56] = ctx->bitlen >> 56;
156 sha256_transform(ctx, ctx->data);
157
158 /* Since this implementation uses little endian byte ordering and SHA uses big endian,
159 reverse all the bytes when copying the final state to the output hash. */
160 for (i = 0; i < 4; ++i) {
161 hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff;
162 hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff;
163 hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff;
164 hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff;
165 hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff;
166 hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff;
167 hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff;
168 hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff;
169 }
170 }
171
sha256sum(unsigned char * data,unsigned int length,unsigned char * hash)172 void sha256sum(unsigned char *data, unsigned int length, unsigned char *hash)
173 {
174 SHA256_CTX ctx;
175
176 sha256_init(&ctx);
177 sha256_update(&ctx, data, length);
178 sha256_final(&ctx, hash);
179 }
180