/* 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;

	}