062e5811 |
1 | /* |
2 | * SHA-256 algorithm as described at |
3 | * |
4 | * http://csrc.nist.gov/cryptval/shs.html |
5 | */ |
6 | |
7 | #include "ssh.h" |
8 | |
9 | /* ---------------------------------------------------------------------- |
10 | * Core SHA256 algorithm: processes 16-word blocks into a message digest. |
11 | */ |
12 | |
13 | #define ror(x,y) ( ((x) << (32-y)) | (((uint32)(x)) >> (y)) ) |
14 | #define shr(x,y) ( (((uint32)(x)) >> (y)) ) |
15 | #define Ch(x,y,z) ( ((x) & (y)) ^ (~(x) & (z)) ) |
16 | #define Maj(x,y,z) ( ((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)) ) |
17 | #define bigsigma0(x) ( ror((x),2) ^ ror((x),13) ^ ror((x),22) ) |
18 | #define bigsigma1(x) ( ror((x),6) ^ ror((x),11) ^ ror((x),25) ) |
19 | #define smallsigma0(x) ( ror((x),7) ^ ror((x),18) ^ shr((x),3) ) |
20 | #define smallsigma1(x) ( ror((x),17) ^ ror((x),19) ^ shr((x),10) ) |
21 | |
22 | void SHA256_Core_Init(SHA256_State *s) { |
23 | s->h[0] = 0x6a09e667; |
24 | s->h[1] = 0xbb67ae85; |
25 | s->h[2] = 0x3c6ef372; |
26 | s->h[3] = 0xa54ff53a; |
27 | s->h[4] = 0x510e527f; |
28 | s->h[5] = 0x9b05688c; |
29 | s->h[6] = 0x1f83d9ab; |
30 | s->h[7] = 0x5be0cd19; |
31 | } |
32 | |
33 | void SHA256_Block(SHA256_State *s, uint32 *block) { |
34 | uint32 w[80]; |
35 | uint32 a,b,c,d,e,f,g,h; |
36 | static const int k[] = { |
37 | 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, |
38 | 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, |
39 | 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, |
40 | 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, |
41 | 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, |
42 | 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, |
43 | 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, |
44 | 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, |
45 | 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, |
46 | 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, |
47 | 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, |
48 | 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, |
49 | 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, |
50 | 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3, |
51 | 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, |
52 | 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2, |
53 | }; |
54 | |
55 | int t; |
56 | |
57 | for (t = 0; t < 16; t++) |
58 | w[t] = block[t]; |
59 | |
60 | for (t = 16; t < 64; t++) |
61 | w[t] = smallsigma1(w[t-2]) + w[t-7] + smallsigma0(w[t-15]) + w[t-16]; |
62 | |
63 | a = s->h[0]; b = s->h[1]; c = s->h[2]; d = s->h[3]; |
64 | e = s->h[4]; f = s->h[5]; g = s->h[6]; h = s->h[7]; |
65 | |
66 | for (t = 0; t < 64; t+=8) { |
67 | uint32 t1, t2; |
68 | |
69 | #define ROUND(j,a,b,c,d,e,f,g,h) \ |
70 | t1 = h + bigsigma1(e) + Ch(e,f,g) + k[j] + w[j]; \ |
71 | t2 = bigsigma0(a) + Maj(a,b,c); \ |
72 | d = d + t1; h = t1 + t2; |
73 | |
74 | ROUND(t+0, a,b,c,d,e,f,g,h); |
75 | ROUND(t+1, h,a,b,c,d,e,f,g); |
76 | ROUND(t+2, g,h,a,b,c,d,e,f); |
77 | ROUND(t+3, f,g,h,a,b,c,d,e); |
78 | ROUND(t+4, e,f,g,h,a,b,c,d); |
79 | ROUND(t+5, d,e,f,g,h,a,b,c); |
80 | ROUND(t+6, c,d,e,f,g,h,a,b); |
81 | ROUND(t+7, b,c,d,e,f,g,h,a); |
82 | } |
83 | |
84 | s->h[0] += a; s->h[1] += b; s->h[2] += c; s->h[3] += d; |
85 | s->h[4] += e; s->h[5] += f; s->h[6] += g; s->h[7] += h; |
86 | } |
87 | |
88 | /* ---------------------------------------------------------------------- |
89 | * Outer SHA256 algorithm: take an arbitrary length byte string, |
90 | * convert it into 16-word blocks with the prescribed padding at |
91 | * the end, and pass those blocks to the core SHA256 algorithm. |
92 | */ |
93 | |
94 | #define BLKSIZE 64 |
95 | |
96 | void SHA256_Init(SHA256_State *s) { |
97 | SHA256_Core_Init(s); |
98 | s->blkused = 0; |
99 | s->lenhi = s->lenlo = 0; |
100 | } |
101 | |
102 | void SHA256_Bytes(SHA256_State *s, const void *p, int len) { |
103 | unsigned char *q = (unsigned char *)p; |
104 | uint32 wordblock[16]; |
105 | uint32 lenw = len; |
106 | int i; |
107 | |
108 | /* |
109 | * Update the length field. |
110 | */ |
111 | s->lenlo += lenw; |
112 | s->lenhi += (s->lenlo < lenw); |
113 | |
114 | if (s->blkused && s->blkused+len < BLKSIZE) { |
115 | /* |
116 | * Trivial case: just add to the block. |
117 | */ |
118 | memcpy(s->block + s->blkused, q, len); |
119 | s->blkused += len; |
120 | } else { |
121 | /* |
122 | * We must complete and process at least one block. |
123 | */ |
124 | while (s->blkused + len >= BLKSIZE) { |
125 | memcpy(s->block + s->blkused, q, BLKSIZE - s->blkused); |
126 | q += BLKSIZE - s->blkused; |
127 | len -= BLKSIZE - s->blkused; |
128 | /* Now process the block. Gather bytes big-endian into words */ |
129 | for (i = 0; i < 16; i++) { |
130 | wordblock[i] = |
131 | ( ((uint32)s->block[i*4+0]) << 24 ) | |
132 | ( ((uint32)s->block[i*4+1]) << 16 ) | |
133 | ( ((uint32)s->block[i*4+2]) << 8 ) | |
134 | ( ((uint32)s->block[i*4+3]) << 0 ); |
135 | } |
136 | SHA256_Block(s, wordblock); |
137 | s->blkused = 0; |
138 | } |
139 | memcpy(s->block, q, len); |
140 | s->blkused = len; |
141 | } |
142 | } |
143 | |
144 | void SHA256_Final(SHA256_State *s, unsigned char *digest) { |
145 | int i; |
146 | int pad; |
147 | unsigned char c[64]; |
148 | uint32 lenhi, lenlo; |
149 | |
150 | if (s->blkused >= 56) |
151 | pad = 56 + 64 - s->blkused; |
152 | else |
153 | pad = 56 - s->blkused; |
154 | |
155 | lenhi = (s->lenhi << 3) | (s->lenlo >> (32-3)); |
156 | lenlo = (s->lenlo << 3); |
157 | |
158 | memset(c, 0, pad); |
159 | c[0] = 0x80; |
160 | SHA256_Bytes(s, &c, pad); |
161 | |
162 | c[0] = (lenhi >> 24) & 0xFF; |
163 | c[1] = (lenhi >> 16) & 0xFF; |
164 | c[2] = (lenhi >> 8) & 0xFF; |
165 | c[3] = (lenhi >> 0) & 0xFF; |
166 | c[4] = (lenlo >> 24) & 0xFF; |
167 | c[5] = (lenlo >> 16) & 0xFF; |
168 | c[6] = (lenlo >> 8) & 0xFF; |
169 | c[7] = (lenlo >> 0) & 0xFF; |
170 | |
171 | SHA256_Bytes(s, &c, 8); |
172 | |
173 | for (i = 0; i < 8; i++) { |
174 | digest[i*4+0] = (s->h[i] >> 24) & 0xFF; |
175 | digest[i*4+1] = (s->h[i] >> 16) & 0xFF; |
176 | digest[i*4+2] = (s->h[i] >> 8) & 0xFF; |
177 | digest[i*4+3] = (s->h[i] >> 0) & 0xFF; |
178 | } |
179 | } |
180 | |
181 | void SHA256_Simple(const void *p, int len, unsigned char *output) { |
182 | SHA256_State s; |
183 | |
184 | SHA256_Init(&s); |
185 | SHA256_Bytes(&s, p, len); |
186 | SHA256_Final(&s, output); |
187 | } |
188 | |
189 | /* |
190 | * Thin abstraction for things where hashes are pluggable. |
191 | */ |
192 | |
193 | static void *sha256_init(void) |
194 | { |
195 | SHA256_State *s; |
196 | |
197 | s = snew(SHA256_State); |
198 | SHA256_Init(s); |
199 | return s; |
200 | } |
201 | |
202 | static void sha256_bytes(void *handle, void *p, int len) |
203 | { |
204 | SHA256_State *s = handle; |
205 | |
206 | SHA256_Bytes(s, p, len); |
207 | } |
208 | |
209 | static void sha256_final(void *handle, unsigned char *output) |
210 | { |
211 | SHA256_State *s = handle; |
212 | |
213 | SHA256_Final(s, output); |
214 | sfree(s); |
215 | } |
216 | |
217 | const struct ssh_hash ssh_sha256 = { |
c6daaa1a |
218 | sha256_init, sha256_bytes, sha256_final, 32, "SHA-256" |
062e5811 |
219 | }; |
220 | |
23159902 |
221 | /* ---------------------------------------------------------------------- |
222 | * The above is the SHA-256 algorithm itself. Now we implement the |
223 | * HMAC wrapper on it. |
224 | */ |
225 | |
226 | static void *sha256_make_context(void) |
227 | { |
228 | return snewn(3, SHA256_State); |
229 | } |
230 | |
231 | static void sha256_free_context(void *handle) |
232 | { |
233 | sfree(handle); |
234 | } |
235 | |
236 | static void sha256_key_internal(void *handle, unsigned char *key, int len) |
237 | { |
238 | SHA256_State *keys = (SHA256_State *)handle; |
239 | unsigned char foo[64]; |
240 | int i; |
241 | |
242 | memset(foo, 0x36, 64); |
243 | for (i = 0; i < len && i < 64; i++) |
244 | foo[i] ^= key[i]; |
245 | SHA256_Init(&keys[0]); |
246 | SHA256_Bytes(&keys[0], foo, 64); |
247 | |
248 | memset(foo, 0x5C, 64); |
249 | for (i = 0; i < len && i < 64; i++) |
250 | foo[i] ^= key[i]; |
251 | SHA256_Init(&keys[1]); |
252 | SHA256_Bytes(&keys[1], foo, 64); |
253 | |
254 | smemclr(foo, 64); /* burn the evidence */ |
255 | } |
256 | |
257 | static void sha256_key(void *handle, unsigned char *key) |
258 | { |
259 | sha256_key_internal(handle, key, 32); |
260 | } |
261 | |
262 | static void hmacsha256_start(void *handle) |
263 | { |
264 | SHA256_State *keys = (SHA256_State *)handle; |
265 | |
266 | keys[2] = keys[0]; /* structure copy */ |
267 | } |
268 | |
269 | static void hmacsha256_bytes(void *handle, unsigned char const *blk, int len) |
270 | { |
271 | SHA256_State *keys = (SHA256_State *)handle; |
272 | SHA256_Bytes(&keys[2], (void *)blk, len); |
273 | } |
274 | |
275 | static void hmacsha256_genresult(void *handle, unsigned char *hmac) |
276 | { |
277 | SHA256_State *keys = (SHA256_State *)handle; |
278 | SHA256_State s; |
279 | unsigned char intermediate[32]; |
280 | |
281 | s = keys[2]; /* structure copy */ |
282 | SHA256_Final(&s, intermediate); |
283 | s = keys[1]; /* structure copy */ |
284 | SHA256_Bytes(&s, intermediate, 32); |
285 | SHA256_Final(&s, hmac); |
286 | } |
287 | |
288 | static void sha256_do_hmac(void *handle, unsigned char *blk, int len, |
289 | unsigned long seq, unsigned char *hmac) |
290 | { |
291 | unsigned char seqbuf[4]; |
292 | |
293 | PUT_32BIT_MSB_FIRST(seqbuf, seq); |
294 | hmacsha256_start(handle); |
295 | hmacsha256_bytes(handle, seqbuf, 4); |
296 | hmacsha256_bytes(handle, blk, len); |
297 | hmacsha256_genresult(handle, hmac); |
298 | } |
299 | |
300 | static void sha256_generate(void *handle, unsigned char *blk, int len, |
301 | unsigned long seq) |
302 | { |
303 | sha256_do_hmac(handle, blk, len, seq, blk + len); |
304 | } |
305 | |
306 | static int hmacsha256_verresult(void *handle, unsigned char const *hmac) |
307 | { |
308 | unsigned char correct[32]; |
309 | hmacsha256_genresult(handle, correct); |
310 | return !memcmp(correct, hmac, 32); |
311 | } |
312 | |
313 | static int sha256_verify(void *handle, unsigned char *blk, int len, |
314 | unsigned long seq) |
315 | { |
316 | unsigned char correct[32]; |
317 | sha256_do_hmac(handle, blk, len, seq, correct); |
318 | return !memcmp(correct, blk + len, 32); |
319 | } |
320 | |
321 | const struct ssh_mac ssh_hmac_sha256 = { |
322 | sha256_make_context, sha256_free_context, sha256_key, |
323 | sha256_generate, sha256_verify, |
324 | hmacsha256_start, hmacsha256_bytes, |
325 | hmacsha256_genresult, hmacsha256_verresult, |
326 | "hmac-sha2-256", |
327 | 32, |
328 | "HMAC-SHA-256" |
329 | }; |
330 | |
062e5811 |
331 | #ifdef TEST |
332 | |
333 | #include <stdio.h> |
334 | #include <stdlib.h> |
335 | #include <assert.h> |
336 | |
337 | int main(void) { |
338 | unsigned char digest[32]; |
339 | int i, j, errors; |
340 | |
341 | struct { |
342 | const char *teststring; |
343 | unsigned char digest[32]; |
344 | } tests[] = { |
345 | { "abc", { |
346 | 0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea, |
347 | 0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23, |
348 | 0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c, |
349 | 0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad, |
350 | } }, |
351 | { "abcdbcdecdefdefgefghfghighijhijkijkljklmklmnlmnomnopnopq", { |
352 | 0x24, 0x8d, 0x6a, 0x61, 0xd2, 0x06, 0x38, 0xb8, |
353 | 0xe5, 0xc0, 0x26, 0x93, 0x0c, 0x3e, 0x60, 0x39, |
354 | 0xa3, 0x3c, 0xe4, 0x59, 0x64, 0xff, 0x21, 0x67, |
355 | 0xf6, 0xec, 0xed, 0xd4, 0x19, 0xdb, 0x06, 0xc1, |
356 | } }, |
357 | }; |
358 | |
359 | errors = 0; |
360 | |
361 | for (i = 0; i < sizeof(tests) / sizeof(*tests); i++) { |
362 | SHA256_Simple(tests[i].teststring, |
363 | strlen(tests[i].teststring), digest); |
364 | for (j = 0; j < 32; j++) { |
365 | if (digest[j] != tests[i].digest[j]) { |
366 | fprintf(stderr, |
367 | "\"%s\" digest byte %d should be 0x%02x, is 0x%02x\n", |
368 | tests[i].teststring, j, tests[i].digest[j], digest[j]); |
369 | errors++; |
370 | } |
371 | } |
372 | } |
373 | |
374 | printf("%d errors\n", errors); |
375 | |
376 | return 0; |
377 | } |
378 | |
379 | #endif |