1 #include "iwsha2.h"
2 #include <string.h>
3 #include <stdio.h>
4
5 #define CHUNK_SIZE 64
6 #define TOTAL_LEN_LEN 8
7
8 /*
9 * Comments from pseudo-code at https://en.wikipedia.org/wiki/SHA-2 are reproduced here.
10 * When useful for clarification, portions of the pseudo-code are reproduced here too.
11 */
12
13 /*
14 * Initialize array of round constants:
15 * (first 32 bits of the fractional parts of the cube roots of the first 64 primes 2..311):
16 */
17 static const uint32_t k[] = {
18 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
19 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
20 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
21 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
22 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
23 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
24 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
25 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
26 };
27
28 struct buffer_state {
29 const uint8_t *p;
30 size_t len;
31 size_t total_len;
32 int single_one_delivered; /* bool */
33 int total_len_delivered; /* bool */
34 };
35
right_rot(uint32_t value,unsigned int count)36 IW_INLINE uint32_t right_rot(uint32_t value, unsigned int count) {
37 /*
38 * Defined behaviour in standard C for all count where 0 < count < 32,
39 * which is what we need here.
40 */
41 return value >> count | value << (32 - count);
42 }
43
init_buf_state(struct buffer_state * state,const void * input,size_t len)44 static void init_buf_state(struct buffer_state *state, const void *input, size_t len) {
45 state->p = input;
46 state->len = len;
47 state->total_len = len;
48 state->single_one_delivered = 0;
49 state->total_len_delivered = 0;
50 }
51
52 /* Return value: bool */
calc_chunk(uint8_t chunk[CHUNK_SIZE],struct buffer_state * state)53 static int calc_chunk(uint8_t chunk[CHUNK_SIZE], struct buffer_state *state) {
54 size_t space_in_chunk;
55
56 if (state->total_len_delivered) {
57 return 0;
58 }
59
60 if (state->len >= CHUNK_SIZE) {
61 memcpy(chunk, state->p, CHUNK_SIZE);
62 state->p += CHUNK_SIZE;
63 state->len -= CHUNK_SIZE;
64 return 1;
65 }
66
67 memcpy(chunk, state->p, state->len);
68 chunk += state->len;
69 space_in_chunk = CHUNK_SIZE - state->len;
70 state->p += state->len;
71 state->len = 0;
72
73 /* If we are here, space_in_chunk is one at minimum. */
74 if (!state->single_one_delivered) {
75 *chunk++ = 0x80;
76 space_in_chunk -= 1;
77 state->single_one_delivered = 1;
78 }
79
80 /*
81 * Now:
82 * - either there is enough space left for the total length, and we can conclude,
83 * - or there is too little space left, and we have to pad the rest of this chunk with zeroes.
84 * In the latter case, we will conclude at the next invokation of this function.
85 */
86 if (space_in_chunk >= TOTAL_LEN_LEN) {
87 const size_t left = space_in_chunk - TOTAL_LEN_LEN;
88 size_t len = state->total_len;
89 int i;
90 memset(chunk, 0x00, left);
91 chunk += left;
92
93 /* Storing of len * 8 as a big endian 64-bit without overflow. */
94 chunk[7] = (uint8_t)(len << 3);
95 len >>= 5;
96 for (i = 6; i >= 0; i--) {
97 chunk[i] = (uint8_t) len;
98 len >>= 8;
99 }
100 state->total_len_delivered = 1;
101 } else {
102 memset(chunk, 0x00, space_in_chunk);
103 }
104
105 return 1;
106 }
107
108 /*
109 * Limitations:
110 * - Since input is a pointer in RAM, the data to hash should be in RAM, which could be a problem
111 * for large data sizes.
112 * - SHA algorithms theoretically operate on bit strings. However, this implementation has no support
113 * for bit string lengths that are not multiples of eight, and it really operates on arrays of bytes.
114 * In particular, the len parameter is a number of bytes.
115 */
iwsha256(const void * input,size_t len,uint8_t hash_out[32])116 void iwsha256(const void *input, size_t len, uint8_t hash_out[32]) {
117 /*
118 * Note 1: All integers (expect indexes) are 32-bit unsigned integers and addition is calculated modulo 2^32.
119 * Note 2: For each round, there is one round constant k[i] and one entry in the message schedule array w[i], 0 = i = 63
120 * Note 3: The compression function uses 8 working variables, a through h
121 * Note 4: Big-endian convention is used when expressing the constants in this pseudocode,
122 * and when parsing message block data from bytes to words, for example,
123 * the first word of the input message "abc" after padding is 0x61626380
124 */
125
126 /*
127 * Initialize hash values:
128 * (first 32 bits of the fractional parts of the square roots of the first 8 primes 2..19):
129 */
130 uint32_t h[] = { 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 };
131 unsigned i, j;
132
133 /* 512-bit chunks is what we will operate on. */
134 uint8_t chunk[64];
135
136 struct buffer_state state;
137
138 init_buf_state(&state, input, len);
139
140 while (calc_chunk(chunk, &state)) {
141 uint32_t ah[8];
142
143 const uint8_t *p = chunk;
144
145 /* Initialize working variables to current hash value: */
146 for (i = 0; i < 8; i++) {
147 ah[i] = h[i];
148 }
149
150 /* Compression function main loop: */
151 for (i = 0; i < 4; i++) {
152 /*
153 * The w-array is really w[64], but since we only need
154 * 16 of them at a time, we save stack by calculating
155 * 16 at a time.
156 *
157 * This optimization was not there initially and the
158 * rest of the comments about w[64] are kept in their
159 * initial state.
160 */
161
162 /*
163 * create a 64-entry message schedule array w[0..63] of 32-bit words
164 * (The initial values in w[0..63] don't matter, so many implementations zero them here)
165 * copy chunk into first 16 words w[0..15] of the message schedule array
166 */
167 uint32_t w[16];
168
169 for (j = 0; j < 16; j++) {
170 if (i == 0) {
171 w[j] = (uint32_t) p[0] << 24 | (uint32_t) p[1] << 16 |
172 (uint32_t) p[2] << 8 | (uint32_t) p[3];
173 p += 4;
174 } else {
175 /* Extend the first 16 words into the remaining 48 words w[16..63] of the message schedule array: */
176 const uint32_t s0 = right_rot(w[(j + 1) & 0xf], 7) ^ right_rot(w[(j + 1) & 0xf], 18) ^ (w[(j + 1) & 0xf] >> 3);
177 const uint32_t s1 = right_rot(w[(j + 14) & 0xf], 17) ^ right_rot(w[(j + 14) & 0xf], 19) ^ (w[(j + 14) & 0xf] >> 10);
178 w[j] = w[j] + s0 + w[(j + 9) & 0xf] + s1;
179 }
180 const uint32_t s1 = right_rot(ah[4], 6) ^ right_rot(ah[4], 11) ^ right_rot(ah[4], 25);
181 const uint32_t ch = (ah[4] & ah[5]) ^ (~ah[4] & ah[6]);
182 const uint32_t temp1 = ah[7] + s1 + ch + k[i << 4 | j] + w[j];
183 const uint32_t s0 = right_rot(ah[0], 2) ^ right_rot(ah[0], 13) ^ right_rot(ah[0], 22);
184 const uint32_t maj = (ah[0] & ah[1]) ^ (ah[0] & ah[2]) ^ (ah[1] & ah[2]);
185 const uint32_t temp2 = s0 + maj;
186
187 ah[7] = ah[6];
188 ah[6] = ah[5];
189 ah[5] = ah[4];
190 ah[4] = ah[3] + temp1;
191 ah[3] = ah[2];
192 ah[2] = ah[1];
193 ah[1] = ah[0];
194 ah[0] = temp1 + temp2;
195 }
196 }
197
198 /* Add the compressed chunk to the current hash value: */
199 for (i = 0; i < 8; i++) {
200 h[i] += ah[i];
201 }
202 }
203
204 /* Produce the final hash value (big-endian): */
205 for (i = 0, j = 0; i < 8; i++) {
206 hash_out[j++] = (uint8_t)(h[i] >> 24);
207 hash_out[j++] = (uint8_t)(h[i] >> 16);
208 hash_out[j++] = (uint8_t)(h[i] >> 8);
209 hash_out[j++] = (uint8_t) h[i];
210 }
211 }
212
iwsha256str(const void * input,size_t len,char str_out[65])213 void iwsha256str(const void *input, size_t len, char str_out[65]) {
214 uint8_t hash[32];
215 iwsha256(input, len, hash);
216 iwhash2str(hash, str_out);
217 }
218
iwhash2str(uint8_t hash[32],char str_out[65])219 void iwhash2str(uint8_t hash[32], char str_out[65]) {
220 for (int i = 0; i < 32; i++) {
221 str_out += sprintf(str_out, "%02x", hash[i]);
222 }
223 }
224