[thirdparty/openssl.git] / crypto / bn / bn_recp.c

/* crypto/bn/bn_recp.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.]
 */

#include <stdio.h>
#include "cryptlib.h"
#include "bn_lcl.h"

void BN_RECP_CTX_init(BN_RECP_CTX *recp)
	{
	BN_init(&(recp->N));
	BN_init(&(recp->Nr));
	recp->num_bits=0;
	recp->flags=0;
	}

BN_RECP_CTX *BN_RECP_CTX_new(void)
	{
	BN_RECP_CTX *ret;

	if ((ret=(BN_RECP_CTX *)OPENSSL_malloc(sizeof(BN_RECP_CTX))) == NULL)
		return(NULL);

	BN_RECP_CTX_init(ret);
	ret->flags=BN_FLG_MALLOCED;
	return(ret);
	}

void BN_RECP_CTX_free(BN_RECP_CTX *recp)
	{
	if(recp == NULL)
	    return;

	BN_free(&(recp->N));
	BN_free(&(recp->Nr));
	if (recp->flags & BN_FLG_MALLOCED)
		OPENSSL_free(recp);
	}

int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
	{
	BN_copy(&(recp->N),d);
	BN_zero(&(recp->Nr));
	recp->num_bits=BN_num_bits(d);
	recp->shift=0;
	return(1);
	}

int BN_mod_mul_reciprocal(BIGNUM *r, BIGNUM *x, BIGNUM *y, BN_RECP_CTX *recp,
	     BN_CTX *ctx)
	{
	int ret=0;
	BIGNUM *a;

	BN_CTX_start(ctx);
	if ((a = BN_CTX_get(ctx)) == NULL) goto err;
	if (y != NULL)
		{
		if (x == y)
			{ if (!BN_sqr(a,x,ctx)) goto err; }
		else
			{ if (!BN_mul(a,x,y,ctx)) goto err; }
		}
	else
		a=x; /* Just do the mod */

	BN_div_recp(NULL,r,a,recp,ctx);
	ret=1;
err:
	BN_CTX_end(ctx);
	return(ret);
	}

int BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
	     BN_CTX *ctx)
	{
	int i,j,ret=0;
	BIGNUM *a,*b,*d,*r;

	BN_CTX_start(ctx);
	a=BN_CTX_get(ctx);
	b=BN_CTX_get(ctx);
	if (dv != NULL)
		d=dv;
	else
		d=BN_CTX_get(ctx);
	if (rem != NULL)
		r=rem;
	else
		r=BN_CTX_get(ctx);
	if (a == NULL || b == NULL || d == NULL || r == NULL) goto err;

	if (BN_ucmp(m,&(recp->N)) < 0)
		{
		BN_zero(d);
		BN_copy(r,m);
		BN_CTX_end(ctx);
		return(1);
		}

	/* We want the remainder
	 * Given input of ABCDEF / ab
	 * we need multiply ABCDEF by 3 digests of the reciprocal of ab
	 *
	 */
	i=BN_num_bits(m);

	j=recp->num_bits<<1;
	if (j>i) i=j;
	j>>=1;

	if (i != recp->shift)
		recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
			i,ctx);

	if (!BN_rshift(a,m,j)) goto err;
	if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
	if (!BN_rshift(d,b,i-j)) goto err;
	d->neg=0;
	if (!BN_mul(b,&(recp->N),d,ctx)) goto err;
	if (!BN_usub(r,m,b)) goto err;
	r->neg=0;

#if 1
	j=0;
	while (BN_ucmp(r,&(recp->N)) >= 0)
		{
		if (j++ > 2)
			{
			BNerr(BN_F_BN_MOD_MUL_RECIPROCAL,BN_R_BAD_RECIPROCAL);
			goto err;
			}
		if (!BN_usub(r,r,&(recp->N))) goto err;
		if (!BN_add_word(d,1)) goto err;
		}
#endif

	r->neg=BN_is_zero(r)?0:m->neg;
	d->neg=m->neg^recp->N.neg;
	ret=1;
err:
	BN_CTX_end(ctx);
	return(ret);
	} 

/* len is the expected size of the result
 * We actually calculate with an extra word of precision, so
 * we can do faster division if the remainder is not required.
 */
int BN_reciprocal(BIGNUM *r, BIGNUM *m, int len, BN_CTX *ctx)
	{
	int ret= -1;
	BIGNUM t;

	BN_init(&t);

	BN_zero(&t);
	if (!BN_set_bit(&t,len)) goto err;

	if (!BN_div(r,NULL,&t,m,ctx)) goto err;
	ret=len;
err:
	BN_free(&t);
	return(ret);
	}
Commit	Line	Data
d02b48c6	1	/* crypto/bn/bn_recp.c */
58964a49	2	/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
d02b48c6 RE	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	#include <stdio.h>
	60	#include "cryptlib.h"
	61	#include "bn_lcl.h"
	62
6b691a5c	63	void BN_RECP_CTX_init(BN_RECP_CTX *recp)
dfeab068 RE	64	{
	65	BN_init(&(recp->N));
	66	BN_init(&(recp->Nr));
	67	recp->num_bits=0;
	68	recp->flags=0;
	69	}
	70
6b691a5c	71	BN_RECP_CTX *BN_RECP_CTX_new(void)
dfeab068 RE	72	{
	73	BN_RECP_CTX *ret;
	74
26a3a48d	75	if ((ret=(BN_RECP_CTX *)OPENSSL_malloc(sizeof(BN_RECP_CTX))) == NULL)
dfeab068 RE	76	return(NULL);
	77
	78	BN_RECP_CTX_init(ret);
	79	ret->flags=BN_FLG_MALLOCED;
	80	return(ret);
	81	}
	82
6b691a5c	83	void BN_RECP_CTX_free(BN_RECP_CTX *recp)
dfeab068	84	{
e03ddfae BL	85	if(recp == NULL)
	86	return;
	87
dfeab068 RE	88	BN_free(&(recp->N));
	89	BN_free(&(recp->Nr));
	90	if (recp->flags & BN_FLG_MALLOCED)
26a3a48d	91	OPENSSL_free(recp);
dfeab068 RE	92	}
dfeab068 RE	93
84c15db5	94	int BN_RECP_CTX_set(BN_RECP_CTX recp, const BIGNUM d, BN_CTX *ctx)
dfeab068 RE	95	{
	96	BN_copy(&(recp->N),d);
	97	BN_zero(&(recp->Nr));
	98	recp->num_bits=BN_num_bits(d);
	99	recp->shift=0;
	100	return(1);
	101	}
	102
6b691a5c UM	103	int BN_mod_mul_reciprocal(BIGNUM r, BIGNUM x, BIGNUM y, BN_RECP_CTX recp,
6b691a5c UM	104	BN_CTX *ctx)
dfeab068 RE	105	{
	106	int ret=0;
	107	BIGNUM *a;
	108
9b141126 UM	109	BN_CTX_start(ctx);
9b141126 UM	110	if ((a = BN_CTX_get(ctx)) == NULL) goto err;
dfeab068 RE	111	if (y != NULL)
	112	{
	113	if (x == y)
	114	{ if (!BN_sqr(a,x,ctx)) goto err; }
	115	else
	116	{ if (!BN_mul(a,x,y,ctx)) goto err; }
	117	}
	118	else
	119	a=x; /* Just do the mod */
	120
	121	BN_div_recp(NULL,r,a,recp,ctx);
	122	ret=1;
	123	err:
9b141126	124	BN_CTX_end(ctx);
dfeab068 RE	125	return(ret);
	126	}
	127
6b691a5c UM	128	int BN_div_recp(BIGNUM dv, BIGNUM rem, BIGNUM m, BN_RECP_CTX recp,
6b691a5c UM	129	BN_CTX *ctx)
d02b48c6	130	{
63933136	131	int i,j,ret=0;
dfeab068 RE	132	BIGNUM a,b,d,r;
dfeab068 RE	133
9b141126 UM	134	BN_CTX_start(ctx);
	135	a=BN_CTX_get(ctx);
	136	b=BN_CTX_get(ctx);
dfeab068 RE	137	if (dv != NULL)
	138	d=dv;
	139	else
9b141126	140	d=BN_CTX_get(ctx);
dfeab068 RE	141	if (rem != NULL)
	142	r=rem;
	143	else
9b141126 UM	144	r=BN_CTX_get(ctx);
9b141126 UM	145	if (a == NULL \|\| b == NULL \|\| d == NULL \|\| r == NULL) goto err;
dfeab068 RE	146
	147	if (BN_ucmp(m,&(recp->N)) < 0)
	148	{
	149	BN_zero(d);
	150	BN_copy(r,m);
9b141126	151	BN_CTX_end(ctx);
dfeab068 RE	152	return(1);
dfeab068 RE	153	}
d02b48c6	154
dfeab068 RE	155	/* We want the remainder
	156	* Given input of ABCDEF / ab
	157	* we need multiply ABCDEF by 3 digests of the reciprocal of ab
	158	*
	159	*/
	160	i=BN_num_bits(m);
d02b48c6	161
63933136 AP	162	j=recp->num_bits<<1;
	163	if (j>i) i=j;
	164	j>>=1;
dfeab068 RE	165
	166	if (i != recp->shift)
	167	recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
	168	i,ctx);
	169
63933136	170	if (!BN_rshift(a,m,j)) goto err;
dfeab068	171	if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
63933136	172	if (!BN_rshift(d,b,i-j)) goto err;
dfeab068 RE	173	d->neg=0;
	174	if (!BN_mul(b,&(recp->N),d,ctx)) goto err;
	175	if (!BN_usub(r,m,b)) goto err;
	176	r->neg=0;
	177
dfeab068	178	#if 1
63933136	179	j=0;
dfeab068	180	while (BN_ucmp(r,&(recp->N)) >= 0)
d02b48c6 RE	181	{
	182	if (j++ > 2)
	183	{
	184	BNerr(BN_F_BN_MOD_MUL_RECIPROCAL,BN_R_BAD_RECIPROCAL);
	185	goto err;
	186	}
dfeab068 RE	187	if (!BN_usub(r,r,&(recp->N))) goto err;
dfeab068 RE	188	if (!BN_add_word(d,1)) goto err;
d02b48c6	189	}
dfeab068	190	#endif
d02b48c6	191
dfeab068 RE	192	r->neg=BN_is_zero(r)?0:m->neg;
dfeab068 RE	193	d->neg=m->neg^recp->N.neg;
d02b48c6 RE	194	ret=1;
d02b48c6 RE	195	err:
9b141126	196	BN_CTX_end(ctx);
d02b48c6	197	return(ret);
dfeab068	198	}
d02b48c6	199
dfeab068 RE	200	/* len is the expected size of the result
	201	* We actually calculate with an extra word of precision, so
	202	* we can do faster division if the remainder is not required.
	203	*/
6b691a5c	204	int BN_reciprocal(BIGNUM r, BIGNUM m, int len, BN_CTX *ctx)
d02b48c6	205	{
dfeab068 RE	206	int ret= -1;
dfeab068 RE	207	BIGNUM t;
d02b48c6	208
dfeab068	209	BN_init(&t);
d02b48c6	210
dfeab068 RE	211	BN_zero(&t);
dfeab068 RE	212	if (!BN_set_bit(&t,len)) goto err;
d02b48c6	213
dfeab068 RE	214	if (!BN_div(r,NULL,&t,m,ctx)) goto err;
dfeab068 RE	215	ret=len;
d02b48c6	216	err:
dfeab068	217	BN_free(&t);
d02b48c6 RE	218	return(ret);
	219	}
	220