1 /* crypto/rsa/rsa_gen.c */
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
61  * are compatibility wrappers using these functions) are in rsa_depr.c. -
62  * Geoff
63  */
64 
65 #include <stdio.h>
66 #include <time.h>
67 #include "cryptlib.h"
68 #include <openssl/bn.h>
69 #include <openssl/rsa.h>
70 
71 #ifndef OPENSSL_FIPS
72 
73 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
74                               BN_GENCB *cb);
75 
76 /*
77  * NB: this wrapper would normally be placed in rsa_lib.c and the static
78  * implementation would probably be in rsa_eay.c. Nonetheless, is kept here
79  * so that we don't introduce a new linker dependency. Eg. any application
80  * that wasn't previously linking object code related to key-generation won't
81  * have to now just because key-generation is part of RSA_METHOD.
82  */
RSA_generate_key_ex(RSA * rsa,int bits,BIGNUM * e_value,BN_GENCB * cb)83 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
84 {
85     if (rsa->meth->rsa_keygen)
86         return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
87     return rsa_builtin_keygen(rsa, bits, e_value, cb);
88 }
89 
rsa_builtin_keygen(RSA * rsa,int bits,BIGNUM * e_value,BN_GENCB * cb)90 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
91                               BN_GENCB *cb)
92 {
93     BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
94     BIGNUM local_r0, local_d, local_p;
95     BIGNUM *pr0, *d, *p;
96     int bitsp, bitsq, ok = -1, n = 0;
97     BN_CTX *ctx = NULL;
98 
99     ctx = BN_CTX_new();
100     if (ctx == NULL)
101         goto err;
102     BN_CTX_start(ctx);
103     r0 = BN_CTX_get(ctx);
104     r1 = BN_CTX_get(ctx);
105     r2 = BN_CTX_get(ctx);
106     r3 = BN_CTX_get(ctx);
107     if (r3 == NULL)
108         goto err;
109 
110     bitsp = (bits + 1) / 2;
111     bitsq = bits - bitsp;
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_new()) == NULL))
117         goto err;
118     if (!rsa->e && ((rsa->e = BN_new()) == NULL))
119         goto err;
120     if (!rsa->p && ((rsa->p = BN_new()) == NULL))
121         goto err;
122     if (!rsa->q && ((rsa->q = BN_new()) == NULL))
123         goto err;
124     if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL))
125         goto err;
126     if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL))
127         goto err;
128     if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL))
129         goto err;
130 
131     BN_copy(rsa->e, e_value);
132 
133     /* generate p and q */
134     for (;;) {
135         if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
136             goto err;
137         if (!BN_sub(r2, rsa->p, BN_value_one()))
138             goto err;
139         if (!BN_gcd(r1, r2, rsa->e, ctx))
140             goto err;
141         if (BN_is_one(r1))
142             break;
143         if (!BN_GENCB_call(cb, 2, n++))
144             goto err;
145     }
146     if (!BN_GENCB_call(cb, 3, 0))
147         goto err;
148     for (;;) {
149         /*
150          * When generating ridiculously small keys, we can get stuck
151          * continually regenerating the same prime values. Check for this and
152          * bail if it happens 3 times.
153          */
154         unsigned int degenerate = 0;
155         do {
156             if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
157                 goto err;
158         } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
159         if (degenerate == 3) {
160             ok = 0;             /* we set our own err */
161             RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
162             goto err;
163         }
164         if (!BN_sub(r2, rsa->q, BN_value_one()))
165             goto err;
166         if (!BN_gcd(r1, r2, rsa->e, ctx))
167             goto err;
168         if (BN_is_one(r1))
169             break;
170         if (!BN_GENCB_call(cb, 2, n++))
171             goto err;
172     }
173     if (!BN_GENCB_call(cb, 3, 1))
174         goto err;
175     if (BN_cmp(rsa->p, rsa->q) < 0) {
176         tmp = rsa->p;
177         rsa->p = rsa->q;
178         rsa->q = tmp;
179     }
180 
181     /* calculate n */
182     if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))
183         goto err;
184 
185     /* calculate d */
186     if (!BN_sub(r1, rsa->p, BN_value_one()))
187         goto err;               /* p-1 */
188     if (!BN_sub(r2, rsa->q, BN_value_one()))
189         goto err;               /* q-1 */
190     if (!BN_mul(r0, r1, r2, ctx))
191         goto err;               /* (p-1)(q-1) */
192     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
193         pr0 = &local_r0;
194         BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
195     } else
196         pr0 = r0;
197     if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx))
198         goto err;               /* d */
199 
200     /* set up d for correct BN_FLG_CONSTTIME flag */
201     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
202         d = &local_d;
203         BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
204     } else
205         d = rsa->d;
206 
207     /* calculate d mod (p-1) */
208     if (!BN_mod(rsa->dmp1, d, r1, ctx))
209         goto err;
210 
211     /* calculate d mod (q-1) */
212     if (!BN_mod(rsa->dmq1, d, r2, ctx))
213         goto err;
214 
215     /* calculate inverse of q mod p */
216     if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
217         p = &local_p;
218         BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
219     } else
220         p = rsa->p;
221     if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx))
222         goto err;
223 
224     ok = 1;
225  err:
226     if (ok == -1) {
227         RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
228         ok = 0;
229     }
230     if (ctx != NULL) {
231         BN_CTX_end(ctx);
232         BN_CTX_free(ctx);
233     }
234 
235     return ok;
236 }
237 
238 #endif
239