rsa_gen.c revision 312826 
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#ifdef OPENSSL_FIPS
71# include <openssl/fips.h>
72extern int FIPS_rsa_x931_generate_key_ex(RSA *rsa, int bits, BIGNUM *e,
73                                         BN_GENCB *cb);
74#endif
75
76static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
77                              BN_GENCB *cb);
78
79/*
80 * NB: this wrapper would normally be placed in rsa_lib.c and the static
81 * implementation would probably be in rsa_eay.c. Nonetheless, is kept here
82 * so that we don't introduce a new linker dependency. Eg. any application
83 * that wasn't previously linking object code related to key-generation won't
84 * have to now just because key-generation is part of RSA_METHOD.
85 */
86int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
87{
88#ifdef OPENSSL_FIPS
89    if (FIPS_mode() && !(rsa->meth->flags & RSA_FLAG_FIPS_METHOD)
90        && !(rsa->flags & RSA_FLAG_NON_FIPS_ALLOW)) {
91        RSAerr(RSA_F_RSA_GENERATE_KEY_EX, RSA_R_NON_FIPS_RSA_METHOD);
92        return 0;
93    }
94#endif
95    if (rsa->meth->rsa_keygen)
96        return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
97#ifdef OPENSSL_FIPS
98    if (FIPS_mode())
99        return FIPS_rsa_x931_generate_key_ex(rsa, bits, e_value, cb);
100#endif
101    return rsa_builtin_keygen(rsa, bits, e_value, cb);
102}
103
104static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
105                              BN_GENCB *cb)
106{
107    BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
108    BIGNUM local_r0, local_d, local_p;
109    BIGNUM *pr0, *d, *p;
110    int bitsp, bitsq, ok = -1, n = 0;
111    BN_CTX *ctx = NULL;
112
113    ctx = BN_CTX_new();
114    if (ctx == NULL)
115        goto err;
116    BN_CTX_start(ctx);
117    r0 = BN_CTX_get(ctx);
118    r1 = BN_CTX_get(ctx);
119    r2 = BN_CTX_get(ctx);
120    r3 = BN_CTX_get(ctx);
121    if (r3 == NULL)
122        goto err;
123
124    bitsp = (bits + 1) / 2;
125    bitsq = bits - bitsp;
126
127    /* We need the RSA components non-NULL */
128    if (!rsa->n && ((rsa->n = BN_new()) == NULL))
129        goto err;
130    if (!rsa->d && ((rsa->d = BN_new()) == NULL))
131        goto err;
132    if (!rsa->e && ((rsa->e = BN_new()) == NULL))
133        goto err;
134    if (!rsa->p && ((rsa->p = BN_new()) == NULL))
135        goto err;
136    if (!rsa->q && ((rsa->q = BN_new()) == NULL))
137        goto err;
138    if (!rsa->dmp1 && ((rsa->dmp1 = BN_new()) == NULL))
139        goto err;
140    if (!rsa->dmq1 && ((rsa->dmq1 = BN_new()) == NULL))
141        goto err;
142    if (!rsa->iqmp && ((rsa->iqmp = BN_new()) == NULL))
143        goto err;
144
145    if (BN_copy(rsa->e, e_value) == NULL)
146        goto err;
147
148    /* generate p and q */
149    for (;;) {
150        if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
151            goto err;
152        if (!BN_sub(r2, rsa->p, BN_value_one()))
153            goto err;
154        if (!BN_gcd(r1, r2, rsa->e, ctx))
155            goto err;
156        if (BN_is_one(r1))
157            break;
158        if (!BN_GENCB_call(cb, 2, n++))
159            goto err;
160    }
161    if (!BN_GENCB_call(cb, 3, 0))
162        goto err;
163    for (;;) {
164        /*
165         * When generating ridiculously small keys, we can get stuck
166         * continually regenerating the same prime values. Check for this and
167         * bail if it happens 3 times.
168         */
169        unsigned int degenerate = 0;
170        do {
171            if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
172                goto err;
173        } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
174        if (degenerate == 3) {
175            ok = 0;             /* we set our own err */
176            RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
177            goto err;
178        }
179        if (!BN_sub(r2, rsa->q, BN_value_one()))
180            goto err;
181        if (!BN_gcd(r1, r2, rsa->e, ctx))
182            goto err;
183        if (BN_is_one(r1))
184            break;
185        if (!BN_GENCB_call(cb, 2, n++))
186            goto err;
187    }
188    if (!BN_GENCB_call(cb, 3, 1))
189        goto err;
190    if (BN_cmp(rsa->p, rsa->q) < 0) {
191        tmp = rsa->p;
192        rsa->p = rsa->q;
193        rsa->q = tmp;
194    }
195
196    /* calculate n */
197    if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))
198        goto err;
199
200    /* calculate d */
201    if (!BN_sub(r1, rsa->p, BN_value_one()))
202        goto err;               /* p-1 */
203    if (!BN_sub(r2, rsa->q, BN_value_one()))
204        goto err;               /* q-1 */
205    if (!BN_mul(r0, r1, r2, ctx))
206        goto err;               /* (p-1)(q-1) */
207    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
208        pr0 = &local_r0;
209        BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
210    } else
211        pr0 = r0;
212    if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx))
213        goto err;               /* d */
214
215    /* set up d for correct BN_FLG_CONSTTIME flag */
216    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
217        d = &local_d;
218        BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
219    } else
220        d = rsa->d;
221
222    /* calculate d mod (p-1) */
223    if (!BN_mod(rsa->dmp1, d, r1, ctx))
224        goto err;
225
226    /* calculate d mod (q-1) */
227    if (!BN_mod(rsa->dmq1, d, r2, ctx))
228        goto err;
229
230    /* calculate inverse of q mod p */
231    if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
232        p = &local_p;
233        BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
234    } else
235        p = rsa->p;
236    if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx))
237        goto err;
238
239    ok = 1;
240 err:
241    if (ok == -1) {
242        RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
243        ok = 0;
244    }
245    if (ctx != NULL) {
246        BN_CTX_end(ctx);
247        BN_CTX_free(ctx);
248    }
249
250    return ok;
251}
252