1 | /* |
2 | * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. |
3 | * |
4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
5 | * this file except in compliance with the License. You can obtain a copy |
6 | * in the file LICENSE in the source distribution or at |
7 | * https://www.openssl.org/source/license.html |
8 | */ |
9 | |
10 | /* |
11 | * NB: these functions have been "upgraded", the deprecated versions (which |
12 | * are compatibility wrappers using these functions) are in rsa_depr.c. - |
13 | * Geoff |
14 | */ |
15 | |
16 | #include <stdio.h> |
17 | #include <time.h> |
18 | #include "internal/cryptlib.h" |
19 | #include <openssl/bn.h> |
20 | #include "rsa_local.h" |
21 | |
22 | static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value, |
23 | BN_GENCB *cb); |
24 | |
25 | /* |
26 | * NB: this wrapper would normally be placed in rsa_lib.c and the static |
27 | * implementation would probably be in rsa_eay.c. Nonetheless, is kept here |
28 | * so that we don't introduce a new linker dependency. Eg. any application |
29 | * that wasn't previously linking object code related to key-generation won't |
30 | * have to now just because key-generation is part of RSA_METHOD. |
31 | */ |
32 | int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb) |
33 | { |
34 | if (rsa->meth->rsa_keygen != NULL) |
35 | return rsa->meth->rsa_keygen(rsa, bits, e_value, cb); |
36 | |
37 | return RSA_generate_multi_prime_key(rsa, bits, RSA_DEFAULT_PRIME_NUM, |
38 | e_value, cb); |
39 | } |
40 | |
41 | int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, |
42 | BIGNUM *e_value, BN_GENCB *cb) |
43 | { |
44 | #ifndef FIPS_MODE |
45 | /* multi-prime is only supported with the builtin key generation */ |
46 | if (rsa->meth->rsa_multi_prime_keygen != NULL) { |
47 | return rsa->meth->rsa_multi_prime_keygen(rsa, bits, primes, |
48 | e_value, cb); |
49 | } else if (rsa->meth->rsa_keygen != NULL) { |
50 | /* |
51 | * However, if rsa->meth implements only rsa_keygen, then we |
52 | * have to honour it in 2-prime case and assume that it wouldn't |
53 | * know what to do with multi-prime key generated by builtin |
54 | * subroutine... |
55 | */ |
56 | if (primes == 2) |
57 | return rsa->meth->rsa_keygen(rsa, bits, e_value, cb); |
58 | else |
59 | return 0; |
60 | } |
61 | #endif /* FIPS_MODE */ |
62 | return rsa_builtin_keygen(rsa, bits, primes, e_value, cb); |
63 | } |
64 | |
65 | static int rsa_builtin_keygen(RSA *rsa, int bits, int primes, BIGNUM *e_value, |
66 | BN_GENCB *cb) |
67 | { |
68 | #ifdef FIPS_MODE |
69 | if (primes != 2) |
70 | return 0; |
71 | return rsa_sp800_56b_generate_key(rsa, bits, e_value, cb); |
72 | #else |
73 | BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *tmp, *prime; |
74 | int ok = -1, n = 0, bitsr[RSA_MAX_PRIME_NUM], bitse = 0; |
75 | int i = 0, quo = 0, rmd = 0, adj = 0, retries = 0; |
76 | RSA_PRIME_INFO *pinfo = NULL; |
77 | STACK_OF(RSA_PRIME_INFO) *prime_infos = NULL; |
78 | BN_CTX *ctx = NULL; |
79 | BN_ULONG bitst = 0; |
80 | unsigned long error = 0; |
81 | |
82 | if (bits < RSA_MIN_MODULUS_BITS) { |
83 | ok = 0; /* we set our own err */ |
84 | RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL); |
85 | goto err; |
86 | } |
87 | |
88 | if (primes < RSA_DEFAULT_PRIME_NUM || primes > rsa_multip_cap(bits)) { |
89 | ok = 0; /* we set our own err */ |
90 | RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_PRIME_NUM_INVALID); |
91 | goto err; |
92 | } |
93 | |
94 | ctx = BN_CTX_new(); |
95 | if (ctx == NULL) |
96 | goto err; |
97 | BN_CTX_start(ctx); |
98 | r0 = BN_CTX_get(ctx); |
99 | r1 = BN_CTX_get(ctx); |
100 | r2 = BN_CTX_get(ctx); |
101 | if (r2 == NULL) |
102 | goto err; |
103 | |
104 | /* divide bits into 'primes' pieces evenly */ |
105 | quo = bits / primes; |
106 | rmd = bits % primes; |
107 | |
108 | for (i = 0; i < primes; i++) |
109 | bitsr[i] = (i < rmd) ? quo + 1 : quo; |
110 | |
111 | rsa->dirty_cnt++; |
112 | |
113 | /* We need the RSA components non-NULL */ |
114 | if (!rsa->n && ((rsa->n = BN_new()) == NULL)) |
115 | goto err; |
116 | if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL)) |
117 | goto err; |
118 | if (!rsa->e && ((rsa->e = BN_new()) == NULL)) |
119 | goto err; |
120 | if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL)) |
121 | goto err; |
122 | if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL)) |
123 | goto err; |
124 | if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL)) |
125 | goto err; |
126 | if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL)) |
127 | goto err; |
128 | if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL)) |
129 | goto err; |
130 | |
131 | /* initialize multi-prime components */ |
132 | if (primes > RSA_DEFAULT_PRIME_NUM) { |
133 | rsa->version = RSA_ASN1_VERSION_MULTI; |
134 | prime_infos = sk_RSA_PRIME_INFO_new_reserve(NULL, primes - 2); |
135 | if (prime_infos == NULL) |
136 | goto err; |
137 | if (rsa->prime_infos != NULL) { |
138 | /* could this happen? */ |
139 | sk_RSA_PRIME_INFO_pop_free(rsa->prime_infos, rsa_multip_info_free); |
140 | } |
141 | rsa->prime_infos = prime_infos; |
142 | |
143 | /* prime_info from 2 to |primes| -1 */ |
144 | for (i = 2; i < primes; i++) { |
145 | pinfo = rsa_multip_info_new(); |
146 | if (pinfo == NULL) |
147 | goto err; |
148 | (void)sk_RSA_PRIME_INFO_push(prime_infos, pinfo); |
149 | } |
150 | } |
151 | |
152 | if (BN_copy(rsa->e, e_value) == NULL) |
153 | goto err; |
154 | |
155 | /* generate p, q and other primes (if any) */ |
156 | for (i = 0; i < primes; i++) { |
157 | adj = 0; |
158 | retries = 0; |
159 | |
160 | if (i == 0) { |
161 | prime = rsa->p; |
162 | } else if (i == 1) { |
163 | prime = rsa->q; |
164 | } else { |
165 | pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); |
166 | prime = pinfo->r; |
167 | } |
168 | BN_set_flags(prime, BN_FLG_CONSTTIME); |
169 | |
170 | for (;;) { |
171 | redo: |
172 | if (!BN_generate_prime_ex(prime, bitsr[i] + adj, 0, NULL, NULL, cb)) |
173 | goto err; |
174 | /* |
175 | * prime should not be equal to p, q, r_3... |
176 | * (those primes prior to this one) |
177 | */ |
178 | { |
179 | int j; |
180 | |
181 | for (j = 0; j < i; j++) { |
182 | BIGNUM *prev_prime; |
183 | |
184 | if (j == 0) |
185 | prev_prime = rsa->p; |
186 | else if (j == 1) |
187 | prev_prime = rsa->q; |
188 | else |
189 | prev_prime = sk_RSA_PRIME_INFO_value(prime_infos, |
190 | j - 2)->r; |
191 | |
192 | if (!BN_cmp(prime, prev_prime)) { |
193 | goto redo; |
194 | } |
195 | } |
196 | } |
197 | if (!BN_sub(r2, prime, BN_value_one())) |
198 | goto err; |
199 | ERR_set_mark(); |
200 | BN_set_flags(r2, BN_FLG_CONSTTIME); |
201 | if (BN_mod_inverse(r1, r2, rsa->e, ctx) != NULL) { |
202 | /* GCD == 1 since inverse exists */ |
203 | break; |
204 | } |
205 | error = ERR_peek_last_error(); |
206 | if (ERR_GET_LIB(error) == ERR_LIB_BN |
207 | && ERR_GET_REASON(error) == BN_R_NO_INVERSE) { |
208 | /* GCD != 1 */ |
209 | ERR_pop_to_mark(); |
210 | } else { |
211 | goto err; |
212 | } |
213 | if (!BN_GENCB_call(cb, 2, n++)) |
214 | goto err; |
215 | } |
216 | |
217 | bitse += bitsr[i]; |
218 | |
219 | /* calculate n immediately to see if it's sufficient */ |
220 | if (i == 1) { |
221 | /* we get at least 2 primes */ |
222 | if (!BN_mul(r1, rsa->p, rsa->q, ctx)) |
223 | goto err; |
224 | } else if (i != 0) { |
225 | /* modulus n = p * q * r_3 * r_4 ... */ |
226 | if (!BN_mul(r1, rsa->n, prime, ctx)) |
227 | goto err; |
228 | } else { |
229 | /* i == 0, do nothing */ |
230 | if (!BN_GENCB_call(cb, 3, i)) |
231 | goto err; |
232 | continue; |
233 | } |
234 | /* |
235 | * if |r1|, product of factors so far, is not as long as expected |
236 | * (by checking the first 4 bits are less than 0x9 or greater than |
237 | * 0xF). If so, re-generate the last prime. |
238 | * |
239 | * NOTE: This actually can't happen in two-prime case, because of |
240 | * the way factors are generated. |
241 | * |
242 | * Besides, another consideration is, for multi-prime case, even the |
243 | * length modulus is as long as expected, the modulus could start at |
244 | * 0x8, which could be utilized to distinguish a multi-prime private |
245 | * key by using the modulus in a certificate. This is also covered |
246 | * by checking the length should not be less than 0x9. |
247 | */ |
248 | if (!BN_rshift(r2, r1, bitse - 4)) |
249 | goto err; |
250 | bitst = BN_get_word(r2); |
251 | |
252 | if (bitst < 0x9 || bitst > 0xF) { |
253 | /* |
254 | * For keys with more than 4 primes, we attempt longer factor to |
255 | * meet length requirement. |
256 | * |
257 | * Otherwise, we just re-generate the prime with the same length. |
258 | * |
259 | * This strategy has the following goals: |
260 | * |
261 | * 1. 1024-bit factors are efficient when using 3072 and 4096-bit key |
262 | * 2. stay the same logic with normal 2-prime key |
263 | */ |
264 | bitse -= bitsr[i]; |
265 | if (!BN_GENCB_call(cb, 2, n++)) |
266 | goto err; |
267 | if (primes > 4) { |
268 | if (bitst < 0x9) |
269 | adj++; |
270 | else |
271 | adj--; |
272 | } else if (retries == 4) { |
273 | /* |
274 | * re-generate all primes from scratch, mainly used |
275 | * in 4 prime case to avoid long loop. Max retry times |
276 | * is set to 4. |
277 | */ |
278 | i = -1; |
279 | bitse = 0; |
280 | continue; |
281 | } |
282 | retries++; |
283 | goto redo; |
284 | } |
285 | /* save product of primes for further use, for multi-prime only */ |
286 | if (i > 1 && BN_copy(pinfo->pp, rsa->n) == NULL) |
287 | goto err; |
288 | if (BN_copy(rsa->n, r1) == NULL) |
289 | goto err; |
290 | if (!BN_GENCB_call(cb, 3, i)) |
291 | goto err; |
292 | } |
293 | |
294 | if (BN_cmp(rsa->p, rsa->q) < 0) { |
295 | tmp = rsa->p; |
296 | rsa->p = rsa->q; |
297 | rsa->q = tmp; |
298 | } |
299 | |
300 | /* calculate d */ |
301 | |
302 | /* p - 1 */ |
303 | if (!BN_sub(r1, rsa->p, BN_value_one())) |
304 | goto err; |
305 | /* q - 1 */ |
306 | if (!BN_sub(r2, rsa->q, BN_value_one())) |
307 | goto err; |
308 | /* (p - 1)(q - 1) */ |
309 | if (!BN_mul(r0, r1, r2, ctx)) |
310 | goto err; |
311 | /* multi-prime */ |
312 | for (i = 2; i < primes; i++) { |
313 | pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); |
314 | /* save r_i - 1 to pinfo->d temporarily */ |
315 | if (!BN_sub(pinfo->d, pinfo->r, BN_value_one())) |
316 | goto err; |
317 | if (!BN_mul(r0, r0, pinfo->d, ctx)) |
318 | goto err; |
319 | } |
320 | |
321 | { |
322 | BIGNUM *pr0 = BN_new(); |
323 | |
324 | if (pr0 == NULL) |
325 | goto err; |
326 | |
327 | BN_with_flags(pr0, r0, BN_FLG_CONSTTIME); |
328 | if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) { |
329 | BN_free(pr0); |
330 | goto err; /* d */ |
331 | } |
332 | /* We MUST free pr0 before any further use of r0 */ |
333 | BN_free(pr0); |
334 | } |
335 | |
336 | { |
337 | BIGNUM *d = BN_new(); |
338 | |
339 | if (d == NULL) |
340 | goto err; |
341 | |
342 | BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME); |
343 | |
344 | /* calculate d mod (p-1) and d mod (q - 1) */ |
345 | if (!BN_mod(rsa->dmp1, d, r1, ctx) |
346 | || !BN_mod(rsa->dmq1, d, r2, ctx)) { |
347 | BN_free(d); |
348 | goto err; |
349 | } |
350 | |
351 | /* calculate CRT exponents */ |
352 | for (i = 2; i < primes; i++) { |
353 | pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); |
354 | /* pinfo->d == r_i - 1 */ |
355 | if (!BN_mod(pinfo->d, d, pinfo->d, ctx)) { |
356 | BN_free(d); |
357 | goto err; |
358 | } |
359 | } |
360 | |
361 | /* We MUST free d before any further use of rsa->d */ |
362 | BN_free(d); |
363 | } |
364 | |
365 | { |
366 | BIGNUM *p = BN_new(); |
367 | |
368 | if (p == NULL) |
369 | goto err; |
370 | BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME); |
371 | |
372 | /* calculate inverse of q mod p */ |
373 | if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) { |
374 | BN_free(p); |
375 | goto err; |
376 | } |
377 | |
378 | /* calculate CRT coefficient for other primes */ |
379 | for (i = 2; i < primes; i++) { |
380 | pinfo = sk_RSA_PRIME_INFO_value(prime_infos, i - 2); |
381 | BN_with_flags(p, pinfo->r, BN_FLG_CONSTTIME); |
382 | if (!BN_mod_inverse(pinfo->t, pinfo->pp, p, ctx)) { |
383 | BN_free(p); |
384 | goto err; |
385 | } |
386 | } |
387 | |
388 | /* We MUST free p before any further use of rsa->p */ |
389 | BN_free(p); |
390 | } |
391 | |
392 | ok = 1; |
393 | err: |
394 | if (ok == -1) { |
395 | RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN); |
396 | ok = 0; |
397 | } |
398 | BN_CTX_end(ctx); |
399 | BN_CTX_free(ctx); |
400 | return ok; |
401 | #endif /* FIPS_MODE */ |
402 | } |
403 | |