1 /* $OpenBSD: rsa_gen.c,v 1.30 2023/07/08 12:26:45 beck Exp $ */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
8 *
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 *
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 *
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51 * SUCH DAMAGE.
52 *
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
57 */
58
59 #include <stdio.h>
60 #include <time.h>
61
62 #include <openssl/bn.h>
63 #include <openssl/err.h>
64 #include <openssl/rsa.h>
65
66 #include "bn_local.h"
67 #include "rsa_local.h"
68
69 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb);
70
71 int
RSA_generate_key_ex(RSA * rsa,int bits,BIGNUM * e_value,BN_GENCB * cb)72 RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
73 {
74 if (rsa->meth->rsa_keygen)
75 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
76 return rsa_builtin_keygen(rsa, bits, e_value, cb);
77 }
78 LCRYPTO_ALIAS(RSA_generate_key_ex);
79
80 static int
rsa_builtin_keygen(RSA * rsa,int bits,BIGNUM * e_value,BN_GENCB * cb)81 rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
82 {
83 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
84 BIGNUM pr0, d, p;
85 int bitsp, bitsq, ok = -1, n = 0;
86 BN_CTX *ctx = NULL;
87
88 ctx = BN_CTX_new();
89 if (ctx == NULL)
90 goto err;
91 BN_CTX_start(ctx);
92 if ((r0 = BN_CTX_get(ctx)) == NULL)
93 goto err;
94 if ((r1 = BN_CTX_get(ctx)) == NULL)
95 goto err;
96 if ((r2 = BN_CTX_get(ctx)) == NULL)
97 goto err;
98 if ((r3 = BN_CTX_get(ctx)) == NULL)
99 goto err;
100
101 bitsp = (bits + 1) / 2;
102 bitsq = bits - bitsp;
103
104 /* We need the RSA components non-NULL */
105 if (!rsa->n && ((rsa->n = BN_new()) == NULL))
106 goto err;
107 if (!rsa->d && ((rsa->d = BN_new()) == NULL))
108 goto err;
109 if (!rsa->e && ((rsa->e = BN_new()) == NULL))
110 goto err;
111 if (!rsa->p && ((rsa->p = BN_new()) == NULL))
112 goto err;
113 if (!rsa->q && ((rsa->q = BN_new()) == NULL))
114 goto err;
115 if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL))
116 goto err;
117 if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL))
118 goto err;
119 if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL))
120 goto err;
121
122 if (!bn_copy(rsa->e, e_value))
123 goto err;
124
125 /* generate p and q */
126 for (;;) {
127 if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
128 goto err;
129 if (!BN_sub(r2, rsa->p, BN_value_one()))
130 goto err;
131 if (!BN_gcd_ct(r1, r2, rsa->e, ctx))
132 goto err;
133 if (BN_is_one(r1))
134 break;
135 if (!BN_GENCB_call(cb, 2, n++))
136 goto err;
137 }
138 if (!BN_GENCB_call(cb, 3, 0))
139 goto err;
140 for (;;) {
141 /*
142 * When generating ridiculously small keys, we can get stuck
143 * continually regenerating the same prime values. Check for
144 * this and bail if it happens 3 times.
145 */
146 unsigned int degenerate = 0;
147 do {
148 if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL,
149 cb))
150 goto err;
151 } while (BN_cmp(rsa->p, rsa->q) == 0 &&
152 ++degenerate < 3);
153 if (degenerate == 3) {
154 ok = 0; /* we set our own err */
155 RSAerror(RSA_R_KEY_SIZE_TOO_SMALL);
156 goto err;
157 }
158 if (!BN_sub(r2, rsa->q, BN_value_one()))
159 goto err;
160 if (!BN_gcd_ct(r1, r2, rsa->e, ctx))
161 goto err;
162 if (BN_is_one(r1))
163 break;
164 if (!BN_GENCB_call(cb, 2, n++))
165 goto err;
166 }
167 if (!BN_GENCB_call(cb, 3, 1))
168 goto err;
169 if (BN_cmp(rsa->p, rsa->q) < 0) {
170 tmp = rsa->p;
171 rsa->p = rsa->q;
172 rsa->q = tmp;
173 }
174
175 /* calculate n */
176 if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))
177 goto err;
178
179 /* calculate d */
180 if (!BN_sub(r1, rsa->p, BN_value_one())) /* p-1 */
181 goto err;
182 if (!BN_sub(r2, rsa->q, BN_value_one())) /* q-1 */
183 goto err;
184 if (!BN_mul(r0, r1, r2, ctx)) /* (p-1)(q-1) */
185 goto err;
186
187 BN_init(&pr0);
188 BN_with_flags(&pr0, r0, BN_FLG_CONSTTIME);
189
190 if (BN_mod_inverse_ct(rsa->d, rsa->e, &pr0, ctx) == NULL) /* d */
191 goto err;
192
193 /* set up d for correct BN_FLG_CONSTTIME flag */
194 BN_init(&d);
195 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME);
196
197 /* calculate d mod (p-1) */
198 if (!BN_mod_ct(rsa->dmp1, &d, r1, ctx))
199 goto err;
200
201 /* calculate d mod (q-1) */
202 if (!BN_mod_ct(rsa->dmq1, &d, r2, ctx))
203 goto err;
204
205 /* calculate inverse of q mod p */
206 BN_init(&p);
207 BN_with_flags(&p, rsa->p, BN_FLG_CONSTTIME);
208 if (BN_mod_inverse_ct(rsa->iqmp, rsa->q, &p, ctx) == NULL)
209 goto err;
210
211 ok = 1;
212 err:
213 if (ok == -1) {
214 RSAerror(ERR_LIB_BN);
215 ok = 0;
216 }
217 if (ctx != NULL) {
218 BN_CTX_end(ctx);
219 BN_CTX_free(ctx);
220 }
221
222 return ok;
223 }
224
225 RSA *
RSA_generate_key(int bits,unsigned long e_value,void (* callback)(int,int,void *),void * cb_arg)226 RSA_generate_key(int bits, unsigned long e_value,
227 void (*callback)(int, int, void *), void *cb_arg)
228 {
229 BN_GENCB cb;
230 int i;
231 RSA *rsa = RSA_new();
232 BIGNUM *e = BN_new();
233
234 if (!rsa || !e)
235 goto err;
236
237 /* The problem is when building with 8, 16, or 32 BN_ULONG,
238 * unsigned long can be larger */
239 for (i = 0; i < (int)sizeof(unsigned long) * 8; i++) {
240 if (e_value & (1UL << i))
241 if (BN_set_bit(e, i) == 0)
242 goto err;
243 }
244
245 BN_GENCB_set_old(&cb, callback, cb_arg);
246
247 if (RSA_generate_key_ex(rsa, bits, e, &cb)) {
248 BN_free(e);
249 return rsa;
250 }
251 err:
252 BN_free(e);
253 RSA_free(rsa);
254
255 return 0;
256 }
257 LCRYPTO_ALIAS(RSA_generate_key);
258