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      1 /* crypto/rsa/rsa_gen.c */
      2 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com)
      3  * All rights reserved.
      4  *
      5  * This package is an SSL implementation written
      6  * by Eric Young (eay (at) 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 (at) 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 (at) 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 (at) 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 #include "cryptlib.h"
     68 #include <openssl/bn.h>
     69 #include <openssl/rsa.h>
     70 
     71 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb);
     72 
     73 /* NB: this wrapper would normally be placed in rsa_lib.c and the static
     74  * implementation would probably be in rsa_eay.c. Nonetheless, is kept here so
     75  * that we don't introduce a new linker dependency. Eg. any application that
     76  * wasn't previously linking object code related to key-generation won't have to
     77  * now just because key-generation is part of RSA_METHOD. */
     78 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
     79 	{
     80 	if(rsa->meth->rsa_keygen)
     81 		return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);
     82 	return rsa_builtin_keygen(rsa, bits, e_value, cb);
     83 	}
     84 
     85 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)
     86 	{
     87 	BIGNUM *r0=NULL,*r1=NULL,*r2=NULL,*r3=NULL,*tmp;
     88 	BIGNUM local_r0,local_d,local_p;
     89 	BIGNUM *pr0,*d,*p;
     90 	int bitsp,bitsq,ok= -1,n=0;
     91 	BN_CTX *ctx=NULL;
     92 
     93 	ctx=BN_CTX_new();
     94 	if (ctx == NULL) goto err;
     95 	BN_CTX_start(ctx);
     96 	r0 = BN_CTX_get(ctx);
     97 	r1 = BN_CTX_get(ctx);
     98 	r2 = BN_CTX_get(ctx);
     99 	r3 = BN_CTX_get(ctx);
    100 	if (r3 == NULL) goto err;
    101 
    102 	bitsp=(bits+1)/2;
    103 	bitsq=bits-bitsp;
    104 
    105 	/* We need the RSA components non-NULL */
    106 	if(!rsa->n && ((rsa->n=BN_new()) == NULL)) goto err;
    107 	if(!rsa->d && ((rsa->d=BN_new()) == NULL)) goto err;
    108 	if(!rsa->e && ((rsa->e=BN_new()) == NULL)) goto err;
    109 	if(!rsa->p && ((rsa->p=BN_new()) == NULL)) goto err;
    110 	if(!rsa->q && ((rsa->q=BN_new()) == NULL)) goto err;
    111 	if(!rsa->dmp1 && ((rsa->dmp1=BN_new()) == NULL)) goto err;
    112 	if(!rsa->dmq1 && ((rsa->dmq1=BN_new()) == NULL)) goto err;
    113 	if(!rsa->iqmp && ((rsa->iqmp=BN_new()) == NULL)) goto err;
    114 
    115 	BN_copy(rsa->e, e_value);
    116 
    117 	/* generate p and q */
    118 	for (;;)
    119 		{
    120 		if(!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
    121 			goto err;
    122 		if (!BN_sub(r2,rsa->p,BN_value_one())) goto err;
    123 		if (!BN_gcd(r1,r2,rsa->e,ctx)) goto err;
    124 		if (BN_is_one(r1)) break;
    125 		if(!BN_GENCB_call(cb, 2, n++))
    126 			goto err;
    127 		}
    128 	if(!BN_GENCB_call(cb, 3, 0))
    129 		goto err;
    130 	for (;;)
    131 		{
    132 		/* When generating ridiculously small keys, we can get stuck
    133 		 * continually regenerating the same prime values. Check for
    134 		 * this and bail if it happens 3 times. */
    135 		unsigned int degenerate = 0;
    136 		do
    137 			{
    138 			if(!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))
    139 				goto err;
    140 			} while((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));
    141 		if(degenerate == 3)
    142 			{
    143 			ok = 0; /* we set our own err */
    144 			RSAerr(RSA_F_RSA_BUILTIN_KEYGEN,RSA_R_KEY_SIZE_TOO_SMALL);
    145 			goto err;
    146 			}
    147 		if (!BN_sub(r2,rsa->q,BN_value_one())) goto err;
    148 		if (!BN_gcd(r1,r2,rsa->e,ctx)) goto err;
    149 		if (BN_is_one(r1))
    150 			break;
    151 		if(!BN_GENCB_call(cb, 2, n++))
    152 			goto err;
    153 		}
    154 	if(!BN_GENCB_call(cb, 3, 1))
    155 		goto err;
    156 	if (BN_cmp(rsa->p,rsa->q) < 0)
    157 		{
    158 		tmp=rsa->p;
    159 		rsa->p=rsa->q;
    160 		rsa->q=tmp;
    161 		}
    162 
    163 	/* calculate n */
    164 	if (!BN_mul(rsa->n,rsa->p,rsa->q,ctx)) goto err;
    165 
    166 	/* calculate d */
    167 	if (!BN_sub(r1,rsa->p,BN_value_one())) goto err;	/* p-1 */
    168 	if (!BN_sub(r2,rsa->q,BN_value_one())) goto err;	/* q-1 */
    169 	if (!BN_mul(r0,r1,r2,ctx)) goto err;	/* (p-1)(q-1) */
    170 	if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
    171 		{
    172 		  pr0 = &local_r0;
    173 		  BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);
    174 		}
    175 	else
    176 	  pr0 = r0;
    177 	if (!BN_mod_inverse(rsa->d,rsa->e,pr0,ctx)) goto err;	/* d */
    178 
    179 	/* set up d for correct BN_FLG_CONSTTIME flag */
    180 	if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
    181 		{
    182 		d = &local_d;
    183 		BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
    184 		}
    185 	else
    186 		d = rsa->d;
    187 
    188 	/* calculate d mod (p-1) */
    189 	if (!BN_mod(rsa->dmp1,d,r1,ctx)) goto err;
    190 
    191 	/* calculate d mod (q-1) */
    192 	if (!BN_mod(rsa->dmq1,d,r2,ctx)) goto err;
    193 
    194 	/* calculate inverse of q mod p */
    195 	if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
    196 		{
    197 		p = &local_p;
    198 		BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);
    199 		}
    200 	else
    201 		p = rsa->p;
    202 	if (!BN_mod_inverse(rsa->iqmp,rsa->q,p,ctx)) goto err;
    203 
    204 	ok=1;
    205 err:
    206 	if (ok == -1)
    207 		{
    208 		RSAerr(RSA_F_RSA_BUILTIN_KEYGEN,ERR_LIB_BN);
    209 		ok=0;
    210 		}
    211 	if (ctx != NULL)
    212 		{
    213 		BN_CTX_end(ctx);
    214 		BN_CTX_free(ctx);
    215 		}
    216 
    217 	return ok;
    218 	}
    219 
    220