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 <string.h> |
19 | #include "sha256.h" |
20 | |
21 | /****************************** MACROS ******************************/ |
22 | #define ROTLEFT(a,b) (((a) << (b)) | ((a) >> (32-(b)))) |
23 | #define ROTRIGHT(a,b) (((a) >> (b)) | ((a) << (32-(b)))) |
24 | |
25 | #define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z))) |
26 | #define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z))) |
27 | #define EP0(x) (ROTRIGHT(x,2) ^ ROTRIGHT(x,13) ^ ROTRIGHT(x,22)) |
28 | #define EP1(x) (ROTRIGHT(x,6) ^ ROTRIGHT(x,11) ^ ROTRIGHT(x,25)) |
29 | #define SIG0(x) (ROTRIGHT(x,7) ^ ROTRIGHT(x,18) ^ ((x) >> 3)) |
30 | #define SIG1(x) (ROTRIGHT(x,17) ^ ROTRIGHT(x,19) ^ ((x) >> 10)) |
31 | |
32 | /**************************** VARIABLES *****************************/ |
33 | static const WORD k[64] = { |
34 | 0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5, |
35 | 0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174, |
36 | 0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da, |
37 | 0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967, |
38 | 0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85, |
39 | 0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070, |
40 | 0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3, |
41 | 0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2 |
42 | }; |
43 | |
44 | /*********************** FUNCTION DEFINITIONS ***********************/ |
45 | void sha256_transform(SHA256_CTX *ctx, const BYTE data[]) |
46 | { |
47 | WORD a, b, c, d, e, f, g, h, i, j, t1, t2, m[64]; |
48 | |
49 | for (i = 0, j = 0; i < 16; ++i, j += 4) |
50 | m[i] = (data[j] << 24) | (data[j + 1] << 16) | (data[j + 2] << 8) | (data[j + 3]); |
51 | for ( ; i < 64; ++i) |
52 | m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16]; |
53 | |
54 | a = ctx->state[0]; |
55 | b = ctx->state[1]; |
56 | c = ctx->state[2]; |
57 | d = ctx->state[3]; |
58 | e = ctx->state[4]; |
59 | f = ctx->state[5]; |
60 | g = ctx->state[6]; |
61 | h = ctx->state[7]; |
62 | |
63 | for (i = 0; i < 64; ++i) { |
64 | t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i]; |
65 | t2 = EP0(a) + MAJ(a,b,c); |
66 | h = g; |
67 | g = f; |
68 | f = e; |
69 | e = d + t1; |
70 | d = c; |
71 | c = b; |
72 | b = a; |
73 | a = t1 + t2; |
74 | } |
75 | |
76 | ctx->state[0] += a; |
77 | ctx->state[1] += b; |
78 | ctx->state[2] += c; |
79 | ctx->state[3] += d; |
80 | ctx->state[4] += e; |
81 | ctx->state[5] += f; |
82 | ctx->state[6] += g; |
83 | ctx->state[7] += h; |
84 | } |
85 | |
86 | void sha256_init(SHA256_CTX *ctx) |
87 | { |
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 BYTE data[], size_t len) |
101 | { |
102 | WORD i; |
103 | |
104 | for (i = 0; i < len; ++i) { |
105 | ctx->data[ctx->datalen] = data[i]; |
106 | ctx->datalen++; |
107 | if (ctx->datalen == 64) { |
108 | sha256_transform(ctx, data: ctx->data); |
109 | ctx->bitlen += 512; |
110 | ctx->datalen = 0; |
111 | } |
112 | } |
113 | } |
114 | |
115 | void sha256_final(SHA256_CTX *ctx, BYTE hash[]) |
116 | { |
117 | WORD i; |
118 | |
119 | i = ctx->datalen; |
120 | |
121 | // Pad whatever data is left in the buffer. |
122 | if (ctx->datalen < 56) { |
123 | ctx->data[i++] = 0x80; |
124 | while (i < 56) |
125 | ctx->data[i++] = 0x00; |
126 | } |
127 | else { |
128 | ctx->data[i++] = 0x80; |
129 | while (i < 64) |
130 | ctx->data[i++] = 0x00; |
131 | sha256_transform(ctx, data: ctx->data); |
132 | memset(s: ctx->data, c: 0, n: 56); |
133 | } |
134 | |
135 | // Append to the padding the total message's length in bits and transform. |
136 | ctx->bitlen += ctx->datalen * 8; |
137 | ctx->data[63] = ctx->bitlen; |
138 | ctx->data[62] = ctx->bitlen >> 8; |
139 | ctx->data[61] = ctx->bitlen >> 16; |
140 | ctx->data[60] = ctx->bitlen >> 24; |
141 | ctx->data[59] = ctx->bitlen >> 32; |
142 | ctx->data[58] = ctx->bitlen >> 40; |
143 | ctx->data[57] = ctx->bitlen >> 48; |
144 | ctx->data[56] = ctx->bitlen >> 56; |
145 | sha256_transform(ctx, data: ctx->data); |
146 | |
147 | // Since this implementation uses little endian byte ordering and SHA uses big endian, |
148 | // reverse all the bytes when copying the final state to the output hash. |
149 | for (i = 0; i < 4; ++i) { |
150 | hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff; |
151 | hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff; |
152 | hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff; |
153 | hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff; |
154 | hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff; |
155 | hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff; |
156 | hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff; |
157 | hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff; |
158 | } |
159 | } |
160 | |