1 /* $OpenBSD: rsa_gen.c,v 1.25 2022/01/20 11:11:17 inoguchi 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
60 /* NB: these functions have been "upgraded", the deprecated versions (which are
61 * compatibility wrappers using these functions) are in rsa_depr.c.
62 * - Geoff
63 */
64
65 #include <stdio.h>
66 #include <time.h>
67
68 #include <openssl/bn.h>
69 #include <openssl/err.h>
70 #include <openssl/rsa.h>
71
72 #include "bn_lcl.h"
73 #include "rsa_locl.h"
74
75 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb);
76
77 /*
78 * NB: this wrapper would normally be placed in rsa_lib.c and the static
79 * implementation would probably be in rsa_eay.c. Nonetheless, is kept here so
80 * that we don't introduce a new linker dependency. Eg. any application that
81 * wasn't previously linking object code related to key-generation won't have to
82 * now just because key-generation is part of RSA_METHOD.
83 */
84 int
RSA_generate_key_ex(RSA * rsa,int bits,BIGNUM * e_value,BN_GENCB * cb)85 RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
86 {
87 if (rsa->meth->rsa_keygen)
88 return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
89 return rsa_builtin_keygen(rsa, bits, e_value, cb);
90 }
91
92 static int
rsa_builtin_keygen(RSA * rsa,int bits,BIGNUM * e_value,BN_GENCB * cb)93 rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
94 {
95 BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
96 BIGNUM pr0, d, p;
97 int bitsp, bitsq, ok = -1, n = 0;
98 BN_CTX *ctx = NULL;
99
100 ctx = BN_CTX_new();
101 if (ctx == NULL)
102 goto err;
103 BN_CTX_start(ctx);
104 if ((r0 = BN_CTX_get(ctx)) == NULL)
105 goto err;
106 if ((r1 = BN_CTX_get(ctx)) == NULL)
107 goto err;
108 if ((r2 = BN_CTX_get(ctx)) == NULL)
109 goto err;
110 if ((r3 = BN_CTX_get(ctx)) == NULL)
111 goto err;
112
113 bitsp = (bits + 1) / 2;
114 bitsq = bits - bitsp;
115
116 /* We need the RSA components non-NULL */
117 if (!rsa->n && ((rsa->n = BN_new()) == NULL))
118 goto err;
119 if (!rsa->d && ((rsa->d = BN_new()) == NULL))
120 goto err;
121 if (!rsa->e && ((rsa->e = BN_new()) == NULL))
122 goto err;
123 if (!rsa->p && ((rsa->p = BN_new()) == NULL))
124 goto err;
125 if (!rsa->q && ((rsa->q = BN_new()) == NULL))
126 goto err;
127 if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL))
128 goto err;
129 if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL))
130 goto err;
131 if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL))
132 goto err;
133
134 BN_copy(rsa->e, e_value);
135
136 /* generate p and q */
137 for (;;) {
138 if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
139 goto err;
140 if (!BN_sub(r2, rsa->p, BN_value_one()))
141 goto err;
142 if (!BN_gcd_ct(r1, r2, rsa->e, ctx))
143 goto err;
144 if (BN_is_one(r1))
145 break;
146 if (!BN_GENCB_call(cb, 2, n++))
147 goto err;
148 }
149 if (!BN_GENCB_call(cb, 3, 0))
150 goto err;
151 for (;;) {
152 /*
153 * When generating ridiculously small keys, we can get stuck
154 * continually regenerating the same prime values. Check for
155 * this and bail if it happens 3 times.
156 */
157 unsigned int degenerate = 0;
158 do {
159 if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL,
160 cb))
161 goto err;
162 } while (BN_cmp(rsa->p, rsa->q) == 0 &&
163 ++degenerate < 3);
164 if (degenerate == 3) {
165 ok = 0; /* we set our own err */
166 RSAerror(RSA_R_KEY_SIZE_TOO_SMALL);
167 goto err;
168 }
169 if (!BN_sub(r2, rsa->q, BN_value_one()))
170 goto err;
171 if (!BN_gcd_ct(r1, r2, rsa->e, ctx))
172 goto err;
173 if (BN_is_one(r1))
174 break;
175 if (!BN_GENCB_call(cb, 2, n++))
176 goto err;
177 }
178 if (!BN_GENCB_call(cb, 3, 1))
179 goto err;
180 if (BN_cmp(rsa->p, rsa->q) < 0) {
181 tmp = rsa->p;
182 rsa->p = rsa->q;
183 rsa->q = tmp;
184 }
185
186 /* calculate n */
187 if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))
188 goto err;
189
190 /* calculate d */
191 if (!BN_sub(r1, rsa->p, BN_value_one())) /* p-1 */
192 goto err;
193 if (!BN_sub(r2, rsa->q, BN_value_one())) /* q-1 */
194 goto err;
195 if (!BN_mul(r0, r1, r2, ctx)) /* (p-1)(q-1) */
196 goto err;
197
198 BN_init(&pr0);
199 BN_with_flags(&pr0, r0, BN_FLG_CONSTTIME);
200
201 if (BN_mod_inverse_ct(rsa->d, rsa->e, &pr0, ctx) == NULL) /* d */
202 goto err;
203
204 /* set up d for correct BN_FLG_CONSTTIME flag */
205 BN_init(&d);
206 BN_with_flags(&d, rsa->d, BN_FLG_CONSTTIME);
207
208 /* calculate d mod (p-1) */
209 if (!BN_mod_ct(rsa->dmp1, &d, r1, ctx))
210 goto err;
211
212 /* calculate d mod (q-1) */
213 if (!BN_mod_ct(rsa->dmq1, &d, r2, ctx))
214 goto err;
215
216 /* calculate inverse of q mod p */
217 BN_init(&p);
218 BN_with_flags(&p, rsa->p, BN_FLG_CONSTTIME);
219 if (BN_mod_inverse_ct(rsa->iqmp, rsa->q, &p, ctx) == NULL)
220 goto err;
221
222 ok = 1;
223 err:
224 if (ok == -1) {
225 RSAerror(ERR_LIB_BN);
226 ok = 0;
227 }
228 if (ctx != NULL) {
229 BN_CTX_end(ctx);
230 BN_CTX_free(ctx);
231 }
232
233 return ok;
234 }
235