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0 /*********************************************************************
1 * Filename: sha256.c
2 * Author: Brad Conte (brad AT bradconte.com)
3 * Copyright:
4 * Disclaimer: This code is presented "as is" without any guarantees.
5 * Details: Implementation of the SHA-256 hashing algorithm.
6 SHA-256 is one of the three algorithms in the SHA2
7 specification. The others, SHA-384 and SHA-512, are not
8 offered in this implementation.
9 Algorithm specification can be found here:
10 * http://csrc.nist.gov/publications/fips/fips180-2/fips180-2withchangenotice.pdf
11 This implementation uses little endian byte order.
12 *********************************************************************/
13
14 /*************************** HEADER FILES ***************************/
15 #include <stdlib.h>
16 #include <memory.h>
17
18 #define SHA256_BLOCK_SIZE 32
19 typedef unsigned char BYTE;
20 typedef unsigned int WORD;
21
22 typedef struct {
23 BYTE data[64];
24 WORD datalen;
25 unsigned long long bitlen;
26 WORD state[8];
27 } _SHA256_CTX;
28
29 /****************************** MACROS ******************************/
30 #define ROTLEFT(a,b) (((a) << (b)) | ((a) >> (32-(b))))
31 #define ROTRIGHT(a,b) (((a) >> (b)) | ((a) << (32-(b))))
32
33 #define CH(x,y,z) (((x) & (y)) ^ (~(x) & (z)))
34 #define MAJ(x,y,z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
35 #define EP0(x) (ROTRIGHT(x,2) ^ ROTRIGHT(x,13) ^ ROTRIGHT(x,22))
36 #define EP1(x) (ROTRIGHT(x,6) ^ ROTRIGHT(x,11) ^ ROTRIGHT(x,25))
37 #define SIG0(x) (ROTRIGHT(x,7) ^ ROTRIGHT(x,18) ^ ((x) >> 3))
38 #define SIG1(x) (ROTRIGHT(x,17) ^ ROTRIGHT(x,19) ^ ((x) >> 10))
39
40 /**************************** VARIABLES *****************************/
41 static const WORD k[64] = {
42 0x428a2f98,0x71374491,0xb5c0fbcf,0xe9b5dba5,0x3956c25b,0x59f111f1,0x923f82a4,0xab1c5ed5,
43 0xd807aa98,0x12835b01,0x243185be,0x550c7dc3,0x72be5d74,0x80deb1fe,0x9bdc06a7,0xc19bf174,
44 0xe49b69c1,0xefbe4786,0x0fc19dc6,0x240ca1cc,0x2de92c6f,0x4a7484aa,0x5cb0a9dc,0x76f988da,
45 0x983e5152,0xa831c66d,0xb00327c8,0xbf597fc7,0xc6e00bf3,0xd5a79147,0x06ca6351,0x14292967,
46 0x27b70a85,0x2e1b2138,0x4d2c6dfc,0x53380d13,0x650a7354,0x766a0abb,0x81c2c92e,0x92722c85,
47 0xa2bfe8a1,0xa81a664b,0xc24b8b70,0xc76c51a3,0xd192e819,0xd6990624,0xf40e3585,0x106aa070,
48 0x19a4c116,0x1e376c08,0x2748774c,0x34b0bcb5,0x391c0cb3,0x4ed8aa4a,0x5b9cca4f,0x682e6ff3,
49 0x748f82ee,0x78a5636f,0x84c87814,0x8cc70208,0x90befffa,0xa4506ceb,0xbef9a3f7,0xc67178f2
50 };
51
52 /*********************** FUNCTION DEFINITIONS ***********************/
53 void sha256_transform(_SHA256_CTX *ctx, const BYTE data[])
54 {
55 WORD a, b, c, d, e, f, g, h, i, j, t1, t2, m[64];
56
57 for (i = 0, j = 0; i < 16; ++i, j += 4)
58 m[i] = (data[j] << 24) | (data[j + 1] << 16) | (data[j + 2] << 8) | (data[j + 3]);
59 for ( ; i < 64; ++i)
60 m[i] = SIG1(m[i - 2]) + m[i - 7] + SIG0(m[i - 15]) + m[i - 16];
61
62 a = ctx->state[0];
63 b = ctx->state[1];
64 c = ctx->state[2];
65 d = ctx->state[3];
66 e = ctx->state[4];
67 f = ctx->state[5];
68 g = ctx->state[6];
69 h = ctx->state[7];
70
71 for (i = 0; i < 64; ++i) {
72 t1 = h + EP1(e) + CH(e,f,g) + k[i] + m[i];
73 t2 = EP0(a) + MAJ(a,b,c);
74 h = g;
75 g = f;
76 f = e;
77 e = d + t1;
78 d = c;
79 c = b;
80 b = a;
81 a = t1 + t2;
82 }
83
84 ctx->state[0] += a;
85 ctx->state[1] += b;
86 ctx->state[2] += c;
87 ctx->state[3] += d;
88 ctx->state[4] += e;
89 ctx->state[5] += f;
90 ctx->state[6] += g;
91 ctx->state[7] += h;
92 }
93
94 void sha256_init(_SHA256_CTX *ctx)
95 {
96 ctx->datalen = 0;
97 ctx->bitlen = 0;
98 ctx->state[0] = 0x6a09e667;
99 ctx->state[1] = 0xbb67ae85;
100 ctx->state[2] = 0x3c6ef372;
101 ctx->state[3] = 0xa54ff53a;
102 ctx->state[4] = 0x510e527f;
103 ctx->state[5] = 0x9b05688c;
104 ctx->state[6] = 0x1f83d9ab;
105 ctx->state[7] = 0x5be0cd19;
106 }
107
108 void sha256_update(_SHA256_CTX *ctx, const BYTE data[], size_t len)
109 {
110 WORD i;
111
112 for (i = 0; i < len; ++i) {
113 ctx->data[ctx->datalen] = data[i];
114 ctx->datalen++;
115 if (ctx->datalen == 64) {
116 sha256_transform(ctx, ctx->data);
117 ctx->bitlen += 512;
118 ctx->datalen = 0;
119 }
120 }
121 }
122
123 void sha256_final(_SHA256_CTX *ctx, BYTE hash[])
124 {
125 WORD i;
126
127 i = ctx->datalen;
128
129 // Pad whatever data is left in the buffer.
130 if (ctx->datalen < 56) {
131 ctx->data[i++] = 0x80;
132 while (i < 56)
133 ctx->data[i++] = 0x00;
134 }
135 else {
136 ctx->data[i++] = 0x80;
137 while (i < 64)
138 ctx->data[i++] = 0x00;
139 sha256_transform(ctx, ctx->data);
140 memset(ctx->data, 0, 56);
141 }
142
143 // Append to the padding the total message's length in bits and transform.
144 ctx->bitlen += ctx->datalen * 8;
145 ctx->data[63] = ctx->bitlen;
146 ctx->data[62] = ctx->bitlen >> 8;
147 ctx->data[61] = ctx->bitlen >> 16;
148 ctx->data[60] = ctx->bitlen >> 24;
149 ctx->data[59] = ctx->bitlen >> 32;
150 ctx->data[58] = ctx->bitlen >> 40;
151 ctx->data[57] = ctx->bitlen >> 48;
152 ctx->data[56] = ctx->bitlen >> 56;
153 sha256_transform(ctx, ctx->data);
154
155 // Since this implementation uses little endian byte ordering and SHA uses big endian,
156 // reverse all the bytes when copying the final state to the output hash.
157 for (i = 0; i < 4; ++i) {
158 hash[i] = (ctx->state[0] >> (24 - i * 8)) & 0x000000ff;
159 hash[i + 4] = (ctx->state[1] >> (24 - i * 8)) & 0x000000ff;
160 hash[i + 8] = (ctx->state[2] >> (24 - i * 8)) & 0x000000ff;
161 hash[i + 12] = (ctx->state[3] >> (24 - i * 8)) & 0x000000ff;
162 hash[i + 16] = (ctx->state[4] >> (24 - i * 8)) & 0x000000ff;
163 hash[i + 20] = (ctx->state[5] >> (24 - i * 8)) & 0x000000ff;
164 hash[i + 24] = (ctx->state[6] >> (24 - i * 8)) & 0x000000ff;
165 hash[i + 28] = (ctx->state[7] >> (24 - i * 8)) & 0x000000ff;
166 }
167 }
168
169 unsigned char *sha256(const unsigned char *d, size_t n, unsigned char *md)
170 {
171 _SHA256_CTX c;
172 static unsigned char m[SHA256_BLOCK_SIZE];
173
174 if (md == NULL) md = m;
175 sha256_init(&c);
176 sha256_update(&c,d,n);
177 sha256_final(&c, md);
178 explicit_bzero(&c,sizeof(c));
179 return(md);
180 }
181