crypto/rsa/rsa_gen.c

   1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   2  * All rights reserved.
   3  *
   4  * This package is an SSL implementation written
   5  * by Eric Young (eay@cryptsoft.com).
   6  * The implementation was written so as to conform with Netscapes SSL.
   7  *
   8  * This library is free for commercial and non-commercial use as long as
   9  * the following conditions are aheared to.  The following conditions
  10  * apply to all code found in this distribution, be it the RC4, RSA,
  11  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  12  * included with this distribution is covered by the same copyright terms
  13  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  14  *
  15  * Copyright remains Eric Young's, and as such any Copyright notices in
  16  * the code are not to be removed.
  17  * If this package is used in a product, Eric Young should be given attribution
  18  * as the author of the parts of the library used.
  19  * This can be in the form of a textual message at program startup or
  20  * in documentation (online or textual) provided with the package.
  21  *
  22  * Redistribution and use in source and binary forms, with or without
  23  * modification, are permitted provided that the following conditions
  24  * are met:
  25  * 1. Redistributions of source code must retain the copyright
  26  *    notice, this list of conditions and the following disclaimer.
  27  * 2. Redistributions in binary form must reproduce the above copyright
  28  *    notice, this list of conditions and the following disclaimer in the
  29  *    documentation and/or other materials provided with the distribution.
  30  * 3. All advertising materials mentioning features or use of this software
  31  *    must display the following acknowledgement:
  32  *    "This product includes cryptographic software written by
  33  *     Eric Young (eay@cryptsoft.com)"
  34  *    The word 'cryptographic' can be left out if the rouines from the library
  35  *    being used are not cryptographic related :-).
  36  * 4. If you include any Windows specific code (or a derivative thereof) from
  37  *    the apps directory (application code) you must include an acknowledgement:
  38  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  50  * SUCH DAMAGE.
  51  *
  52  * The licence and distribution terms for any publically available version or
  53  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  54  * copied and put under another distribution licence
  55  * [including the GNU Public Licence.]
  56  */
  57
  58 /*
  59  * NB: these functions have been "upgraded", the deprecated versions (which
  60  * are compatibility wrappers using these functions) are in rsa_depr.c. -
  61  * Geoff
  62  */
  63
  64 #include <stdio.h>
  65 #include <time.h>
  66 #include "internal/cryptlib.h"
  67 #include <openssl/bn.h>
  68 #include <openssl/rsa.h>
  69
  70 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
  71                               BN_GENCB *cb);
  72
  73 /*
  74  * NB: this wrapper would normally be placed in rsa_lib.c and the static
  75  * implementation would probably be in rsa_eay.c. Nonetheless, is kept here
  76  * so that we don't introduce a new linker dependency. Eg. any application
  77  * that wasn't previously linking object code related to key-generation won't
  78  * have to now just because key-generation is part of RSA_METHOD.
  79  */
  80 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
  81 {
  82     if (rsa->meth->rsa_keygen)
  83         return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
  84     return rsa_builtin_keygen(rsa, bits, e_value, cb);
  85 }
  86
  87 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value,
  88                               BN_GENCB *cb)
  89 {
  90     BIGNUM *r0 = NULL, *r1 = NULL, *r2 = NULL, *r3 = NULL, *tmp;
  91     int bitsp, bitsq, ok = -1, n = 0;
  92     BN_CTX *ctx = NULL;
  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     r3 = BN_CTX_get(ctx);
 102     if (r3 == NULL)
 103         goto err;
 104
 105     bitsp = (bits + 1) / 2;
 106     bitsq = bits - bitsp;
 107
 108     /* We need the RSA components non-NULL */
 109     if (!rsa->n && ((rsa->n = BN_new()) == NULL))
 110         goto err;
 111     if (!rsa->d && ((rsa->d = BN_secure_new()) == NULL))
 112         goto err;
 113     if (!rsa->e && ((rsa->e = BN_new()) == NULL))
 114         goto err;
 115     if (!rsa->p && ((rsa->p = BN_secure_new()) == NULL))
 116         goto err;
 117     if (!rsa->q && ((rsa->q = BN_secure_new()) == NULL))
 118         goto err;
 119     if (!rsa->dmp1 && ((rsa->dmp1 = BN_secure_new()) == NULL))
 120         goto err;
 121     if (!rsa->dmq1 && ((rsa->dmq1 = BN_secure_new()) == NULL))
 122         goto err;
 123     if (!rsa->iqmp && ((rsa->iqmp = BN_secure_new()) == NULL))
 124         goto err;
 125
 126     BN_copy(rsa->e, e_value);
 127
 128     /* generate p and q */
 129     for (;;) {
 130         if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
 131             goto err;
 132         if (!BN_sub(r2, rsa->p, BN_value_one()))
 133             goto err;
 134         if (!BN_gcd(r1, r2, rsa->e, ctx))
 135             goto err;
 136         if (BN_is_one(r1))
 137             break;
 138         if (!BN_GENCB_call(cb, 2, n++))
 139             goto err;
 140     }
 141     if (!BN_GENCB_call(cb, 3, 0))
 142         goto err;
 143     for (;;) {
 144         /*
 145          * When generating ridiculously small keys, we can get stuck
 146          * continually regenerating the same prime values. Check for this and
 147          * bail if it happens 3 times.
 148          */
 149         unsigned int degenerate = 0;
 150         do {
 151             if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
 152                 goto err;
 153         } while ((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
 154         if (degenerate == 3) {
 155             ok = 0;             /* we set our own err */
 156             RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, RSA_R_KEY_SIZE_TOO_SMALL);
 157             goto err;
 158         }
 159         if (!BN_sub(r2, rsa->q, BN_value_one()))
 160             goto err;
 161         if (!BN_gcd(r1, r2, rsa->e, ctx))
 162             goto err;
 163         if (BN_is_one(r1))
 164             break;
 165         if (!BN_GENCB_call(cb, 2, n++))
 166             goto err;
 167     }
 168     if (!BN_GENCB_call(cb, 3, 1))
 169         goto err;
 170     if (BN_cmp(rsa->p, rsa->q) < 0) {
 171         tmp = rsa->p;
 172         rsa->p = rsa->q;
 173         rsa->q = tmp;
 174     }
 175
 176     /* calculate n */
 177     if (!BN_mul(rsa->n, rsa->p, rsa->q, ctx))
 178         goto err;
 179
 180     /* calculate d */
 181     if (!BN_sub(r1, rsa->p, BN_value_one()))
 182         goto err;               /* p-1 */
 183     if (!BN_sub(r2, rsa->q, BN_value_one()))
 184         goto err;               /* q-1 */
 185     if (!BN_mul(r0, r1, r2, ctx))
 186         goto err;               /* (p-1)(q-1) */
 187     {
 188         BIGNUM *local_r0 = NULL, *pr0;
 189         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 190             pr0 = local_r0 = BN_new();
 191             if (local_r0 == NULL)
 192                 goto err;
 193             BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
 194         } else {
 195             pr0 = r0;
 196         }
 197         if (!BN_mod_inverse(rsa->d, rsa->e, pr0, ctx)) {
 198             BN_free(local_r0);
 199             goto err;               /* d */
 200         }
 201         /* We MUST free local_r0 before any further use of r0 */
 202         BN_free(local_r0);
 203     }
 204
 205     {
 206         BIGNUM *local_d = NULL, *d;
 207         /* set up d for correct BN_FLG_CONSTTIME flag */
 208         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 209             d = local_d = BN_new();
 210             if (local_d == NULL)
 211                 goto err;
 212             BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
 213         } else {
 214             d = rsa->d;
 215         }
 216
 217         if (   /* calculate d mod (p-1) */
 218                !BN_mod(rsa->dmp1, d, r1, ctx)
 219                /* calculate d mod (q-1) */
 220             || !BN_mod(rsa->dmq1, d, r2, ctx)) {
 221             BN_free(local_d);
 222             goto err;
 223         }
 224         /* We MUST free local_d before any further use of rsa->d */
 225         BN_free(local_d);
 226     }
 227
 228     {
 229         BIGNUM *local_p = NULL, *p;
 230
 231         /* calculate inverse of q mod p */
 232         if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME)) {
 233             p = local_p = BN_new();
 234             if (local_p == NULL)
 235                 goto err;
 236             BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
 237         } else {
 238             p = rsa->p;
 239         }
 240         if (!BN_mod_inverse(rsa->iqmp, rsa->q, p, ctx)) {
 241             BN_free(local_p);
 242             goto err;
 243         }
 244         /* We MUST free local_p before any further use of rsa->p */
 245         BN_free(local_p);
 246     }
 247
 248     ok = 1;
 249  err:
 250     if (ok == -1) {
 251         RSAerr(RSA_F_RSA_BUILTIN_KEYGEN, ERR_LIB_BN);
 252         ok = 0;
 253     }
 254     if (ctx != NULL)
 255         BN_CTX_end(ctx);
 256     BN_CTX_free(ctx);
 257
 258     return ok;
 259 }