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 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] = ((WORD) data[j + 0] << 24) | |
50 | ((WORD) data[j + 1] << 16) | |
51 | ((WORD) data[j + 2] << 8) | |
52 | ((WORD) data[j + 3]); |
53 | } |
54 | |
55 | for ( ; i < 64; ++i) |
56 | m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16]; |
57 | |
58 | a = ctx->state[0]; |
59 | b = ctx->state[1]; |
60 | c = ctx->state[2]; |
61 | d = ctx->state[3]; |
62 | e = ctx->state[4]; |
63 | f = ctx->state[5]; |
64 | g = ctx->state[6]; |
65 | h = ctx->state[7]; |
66 | |
67 | for (i = 0; i < 64; ++i) { |
68 | t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i]; |
69 | t2 = EP0(a) + MAJ(a,b,c); |
70 | h = g; |
71 | g = f; |
72 | f = e; |
73 | e = d + t1; |
74 | d = c; |
75 | c = b; |
76 | b = a; |
77 | a = t1 + t2; |
78 | } |
79 | |
80 | ctx->state[0] += a; |
81 | ctx->state[1] += b; |
82 | ctx->state[2] += c; |
83 | ctx->state[3] += d; |
84 | ctx->state[4] += e; |
85 | ctx->state[5] += f; |
86 | ctx->state[6] += g; |
87 | ctx->state[7] += h; |
88 | } |
89 | |
90 | void sha256_init(SHA256_CTX *ctx) |
91 | { |
92 | ctx->datalen = 0; |
93 | ctx->bitlen = 0; |
94 | ctx->state[0] = 0x6a09e667; |
95 | ctx->state[1] = 0xbb67ae85; |
96 | ctx->state[2] = 0x3c6ef372; |
97 | ctx->state[3] = 0xa54ff53a; |
98 | ctx->state[4] = 0x510e527f; |
99 | ctx->state[5] = 0x9b05688c; |
100 | ctx->state[6] = 0x1f83d9ab; |
101 | ctx->state[7] = 0x5be0cd19; |
102 | } |
103 | |
104 | void sha256_update(SHA256_CTX *ctx, const BYTE data[], size_t len) |
105 | { |
106 | WORD i; |
107 | |
108 | for (i = 0; i < len; ++i) { |
109 | ctx->data[ctx->datalen] = data[i]; |
110 | ctx->datalen++; |
111 | if (ctx->datalen == 64) { |
112 | sha256_transform(ctx, ctx->data); |
113 | ctx->bitlen += 512; |
114 | ctx->datalen = 0; |
115 | } |
116 | } |
117 | } |
118 | |
119 | void sha256_final(SHA256_CTX *ctx, BYTE hash[]) |
120 | { |
121 | WORD i; |
122 | |
123 | i = ctx->datalen; |
124 | |
125 | // Pad whatever data is left in the buffer. |
126 | if (ctx->datalen < 56) { |
127 | ctx->data[i++] = 0x80; |
128 | while (i < 56) |
129 | ctx->data[i++] = 0x00; |
130 | } |
131 | else { |
132 | ctx->data[i++] = 0x80; |
133 | while (i < 64) |
134 | ctx->data[i++] = 0x00; |
135 | sha256_transform(ctx, ctx->data); |
136 | memset(ctx->data, 0, 56); |
137 | } |
138 | |
139 | // Append to the padding the total message's length in bits and transform. |
140 | ctx->bitlen += ctx->datalen * 8; |
141 | ctx->data[63] = ctx->bitlen; |
142 | ctx->data[62] = ctx->bitlen >> 8; |
143 | ctx->data[61] = ctx->bitlen >> 16; |
144 | ctx->data[60] = ctx->bitlen >> 24; |
145 | ctx->data[59] = ctx->bitlen >> 32; |
146 | ctx->data[58] = ctx->bitlen >> 40; |
147 | ctx->data[57] = ctx->bitlen >> 48; |
148 | ctx->data[56] = ctx->bitlen >> 56; |
149 | sha256_transform(ctx, ctx->data); |
150 | |
151 | // Since this implementation uses little endian byte ordering and SHA uses big endian, |
152 | // reverse all the bytes when copying the final state to the output hash. |
153 | for (i = 0; i < 4; ++i) { |
154 | hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff; |
155 | hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff; |
156 | hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff; |
157 | hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff; |
158 | hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff; |
159 | hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff; |
160 | hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff; |
161 | hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff; |
162 | } |
163 | } |
164 | |