/* crypto/rsa/rsa_gen.c */

 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)

  * All rights reserved.

  *

  * This package is an SSL implementation written

  * by Eric Young (eay@cryptsoft.com).

  * The implementation was written so as to conform with Netscapes SSL.

  * 

  * This library is free for commercial and non-commercial use as long as

  * the following conditions are aheared to.  The following conditions

  * apply to all code found in this distribution, be it the RC4, RSA,

  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation

  * included with this distribution is covered by the same copyright terms

  * except that the holder is Tim Hudson (tjh@cryptsoft.com).

  * 

  * Copyright remains Eric Young's, and as such any Copyright notices in

  * the code are not to be removed.

  * If this package is used in a product, Eric Young should be given attribution

  * as the author of the parts of the library used.

  * This can be in the form of a textual message at program startup or

  * in documentation (online or textual) provided with the package.

  * 

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions

  * are met:

  * 1. Redistributions of source code must retain the copyright

  *    notice, this list of conditions and the following disclaimer.

  * 2. Redistributions in binary form must reproduce the above copyright

  *    notice, this list of conditions and the following disclaimer in the

  *    documentation and/or other materials provided with the distribution.

  * 3. All advertising materials mentioning features or use of this software

  *    must display the following acknowledgement:

  *    "This product includes cryptographic software written by

  *     Eric Young (eay@cryptsoft.com)"

  *    The word 'cryptographic' can be left out if the rouines from the library

  *    being used are not cryptographic related :-).

  * 4. If you include any Windows specific code (or a derivative thereof) from 

  *    the apps directory (application code) you must include an acknowledgement:

  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"

  * 

  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND

  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

  * SUCH DAMAGE.

  * 

  * The licence and distribution terms for any publically available version or

  * derivative of this code cannot be changed.  i.e. this code cannot simply be

  * copied and put under another distribution licence

  * [including the GNU Public Licence.]

  */

 /* NB: these functions have been "upgraded", the deprecated versions (which are

  * compatibility wrappers using these functions) are in rsa_depr.c.

  * - Geoff

  */

 #include <stdio.h>

 #include <time.h>

 #include "cryptlib.h"

 #include <openssl/bn.h>

 #include <openssl/rsa.h>

 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb);

 /* NB: this wrapper would normally be placed in rsa_lib.c and the static

  * implementation would probably be in rsa_eay.c. Nonetheless, is kept here so

  * that we don't introduce a new linker dependency. Eg. any application that

  * wasn't previously linking object code related to key-generation won't have to

  * now just because key-generation is part of RSA_METHOD. */

 EXPORT_C int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)

 	{

 	if(rsa->meth->rsa_keygen)

 		return rsa->meth->rsa_keygen(rsa, bits, e_value, cb);

 	return rsa_builtin_keygen(rsa, bits, e_value, cb);

 	}

 static int rsa_builtin_keygen(RSA *rsa, int bits, BIGNUM *e_value, BN_GENCB *cb)

 	{

 	BIGNUM *r0=NULL,*r1=NULL,*r2=NULL,*r3=NULL,*tmp;

 	BIGNUM local_r0,local_d,local_p;

 	BIGNUM *pr0,*d,*p;

 	int bitsp,bitsq,ok= -1,n=0;

 	BN_CTX *ctx=NULL;

 	ctx=BN_CTX_new();

 	if (ctx == NULL) goto err;

 	BN_CTX_start(ctx);

 	r0 = BN_CTX_get(ctx);

 	r1 = BN_CTX_get(ctx);

 	r2 = BN_CTX_get(ctx);

 	r3 = BN_CTX_get(ctx);

 	if (r3 == NULL) goto err;

 	bitsp=(bits+1)/2;

 	bitsq=bits-bitsp;

 	/* We need the RSA components non-NULL */

 	if(!rsa->n && ((rsa->n=BN_new()) == NULL)) goto err;

 	if(!rsa->d && ((rsa->d=BN_new()) == NULL)) goto err;

 	if(!rsa->e && ((rsa->e=BN_new()) == NULL)) goto err;

 	if(!rsa->p && ((rsa->p=BN_new()) == NULL)) goto err;

 	if(!rsa->q && ((rsa->q=BN_new()) == NULL)) goto err;

 	if(!rsa->dmp1 && ((rsa->dmp1=BN_new()) == NULL)) goto err;

 	if(!rsa->dmq1 && ((rsa->dmq1=BN_new()) == NULL)) goto err;

 	if(!rsa->iqmp && ((rsa->iqmp=BN_new()) == NULL)) goto err;

 	BN_copy(rsa->e, e_value);

 	/* generate p and q */

 	for (;;)

 		{

 		if(!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))

 			goto err;

 		if (!BN_sub(r2,rsa->p,BN_value_one())) goto err;

 		if (!BN_gcd(r1,r2,rsa->e,ctx)) goto err;

 		if (BN_is_one(r1)) break;

 		if(!BN_GENCB_call(cb, 2, n++))

 			goto err;

 		}

 	if(!BN_GENCB_call(cb, 3, 0))

 		goto err;

 	for (;;)

 		{

 		/* When generating ridiculously small keys, we can get stuck

 		 * continually regenerating the same prime values. Check for

 		 * this and bail if it happens 3 times. */

 		unsigned int degenerate = 0;

 		do

 			{

 			if(!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL, cb))

 				goto err;

 			} while((BN_cmp(rsa->p, rsa->q) == 0) && (++degenerate < 3));

 		if(degenerate == 3)

 			{

 			ok = 0; /* we set our own err */

 			RSAerr(RSA_F_RSA_BUILTIN_KEYGEN,RSA_R_KEY_SIZE_TOO_SMALL);

 			goto err;

 			}

 		if (!BN_sub(r2,rsa->q,BN_value_one())) goto err;

 		if (!BN_gcd(r1,r2,rsa->e,ctx)) goto err;

 		if (BN_is_one(r1))

 			break;

 		if(!BN_GENCB_call(cb, 2, n++))

 			goto err;

 		}

 	if(!BN_GENCB_call(cb, 3, 1))

 		goto err;

 	if (BN_cmp(rsa->p,rsa->q) < 0)

 		{

 		tmp=rsa->p;

 		rsa->p=rsa->q;

 		rsa->q=tmp;

 		}

 	/* calculate n */

 	if (!BN_mul(rsa->n,rsa->p,rsa->q,ctx)) goto err;

 	/* calculate d */

 	if (!BN_sub(r1,rsa->p,BN_value_one())) goto err;	/* p-1 */

 	if (!BN_sub(r2,rsa->q,BN_value_one())) goto err;	/* q-1 */

 	if (!BN_mul(r0,r1,r2,ctx)) goto err;	/* (p-1)(q-1) */

 	if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))

 		{

 		  pr0 = &local_r0;

 		  BN_with_flags(pr0, r0, BN_FLG_CONSTTIME);

 		}

 	else

 	  pr0 = r0;

 	if (!BN_mod_inverse(rsa->d,rsa->e,pr0,ctx)) goto err;	/* d */

 	/* set up d for correct BN_FLG_CONSTTIME flag */

 	if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))

 		{

 		d = &local_d;

 		BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);

 		}

 	else

 		d = rsa->d;

 	/* calculate d mod (p-1) */

 	if (!BN_mod(rsa->dmp1,d,r1,ctx)) goto err;

 	/* calculate d mod (q-1) */

 	if (!BN_mod(rsa->dmq1,d,r2,ctx)) goto err;

 	/* calculate inverse of q mod p */

 	if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))

 		{

 		p = &local_p;

 		BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);

 		}

 	else

 		p = rsa->p;

 	if (!BN_mod_inverse(rsa->iqmp,rsa->q,p,ctx)) goto err;

 	ok=1;

 err:

 	if (ok == -1)

 		{

 		RSAerr(RSA_F_RSA_BUILTIN_KEYGEN,ERR_LIB_BN);

 		ok=0;

 		}

 	if (ctx != NULL)

 		{

 		BN_CTX_end(ctx);

 		BN_CTX_free(ctx);

 		}

 	return ok;

 	}