[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)
	{
	if (!BN_copy(&(recp->N),d)) return 0;
	BN_zero(&(recp->Nr));
	recp->num_bits=BN_num_bits(d);
	recp->shift=0;
	return(1);
	}

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

	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; }
		ca = a;
		}
	else
		ca=x; /* Just do the mod */

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

int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const 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);
		if (!BN_copy(r,m)) return 0;
		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 := max(BN_num_bits(m), 2*BN_num_bits(N)) */
	i=BN_num_bits(m);
	j=recp->num_bits<<1;
	if (j>i) i=j;

	/* Nr := round(2^i / N) */
	if (i != recp->shift)
		recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
			i,ctx); /* BN_reciprocal returns i, or -1 for an error */
	if (recp->shift == -1) goto err;

	/* d := |round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))|
	 *    = |round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))|
	 *   <= |(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)|
	 *    = |m/N|
	 */
	if (!BN_rshift(a,m,recp->num_bits)) goto err;
	if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
	if (!BN_rshift(d,b,i-recp->num_bits)) 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_DIV_RECP,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);
	bn_check_top(dv);
	bn_check_top(rem);
	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.
 */
/* r := 2^len / m */
int BN_reciprocal(BIGNUM *r, const BIGNUM *m, size_t len, BN_CTX *ctx)
	{
	int ret= -1;
	BIGNUM *t;

	BN_CTX_start(ctx);
	if((t = BN_CTX_get(ctx)) == NULL) goto err;

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

	if (!BN_div(r,NULL,t,m,ctx)) goto err;

	ret=len;
err:
	bn_check_top(r);
	BN_CTX_end(ctx);
	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	95	{
8dea52fa	96	if (!BN_copy(&(recp->N),d)) return 0;
b6358c89	97	BN_zero(&(recp->Nr));
dfeab068 RE	98	recp->num_bits=BN_num_bits(d);
	99	recp->shift=0;
	100	return(1);
	101	}
	102
020fc820 RL	103	int BN_mod_mul_reciprocal(BIGNUM r, const BIGNUM x, const BIGNUM *y,
020fc820 RL	104	BN_RECP_CTX recp, BN_CTX ctx)
dfeab068 RE	105	{
	106	int ret=0;
	107	BIGNUM *a;
020fc820	108	const BIGNUM *ca;
dfeab068	109
9b141126 UM	110	BN_CTX_start(ctx);
9b141126 UM	111	if ((a = BN_CTX_get(ctx)) == NULL) goto err;
dfeab068 RE	112	if (y != NULL)
	113	{
	114	if (x == y)
	115	{ if (!BN_sqr(a,x,ctx)) goto err; }
	116	else
	117	{ if (!BN_mul(a,x,y,ctx)) goto err; }
020fc820	118	ca = a;
dfeab068 RE	119	}
dfeab068 RE	120	else
020fc820	121	ca=x; /* Just do the mod */
dfeab068	122
8dea52fa	123	ret = BN_div_recp(NULL,r,ca,recp,ctx);
dfeab068	124	err:
9b141126	125	BN_CTX_end(ctx);
d870740c	126	bn_check_top(r);
dfeab068 RE	127	return(ret);
	128	}
	129
020fc820 RL	130	int BN_div_recp(BIGNUM dv, BIGNUM rem, const BIGNUM *m,
020fc820 RL	131	BN_RECP_CTX recp, BN_CTX ctx)
d02b48c6	132	{
63933136	133	int i,j,ret=0;
dfeab068 RE	134	BIGNUM a,b,d,r;
dfeab068 RE	135
9b141126 UM	136	BN_CTX_start(ctx);
	137	a=BN_CTX_get(ctx);
	138	b=BN_CTX_get(ctx);
dfeab068 RE	139	if (dv != NULL)
	140	d=dv;
	141	else
9b141126	142	d=BN_CTX_get(ctx);
dfeab068 RE	143	if (rem != NULL)
	144	r=rem;
	145	else
9b141126 UM	146	r=BN_CTX_get(ctx);
9b141126 UM	147	if (a == NULL \|\| b == NULL \|\| d == NULL \|\| r == NULL) goto err;
dfeab068 RE	148
	149	if (BN_ucmp(m,&(recp->N)) < 0)
	150	{
b6358c89	151	BN_zero(d);
8dea52fa	152	if (!BN_copy(r,m)) return 0;
9b141126	153	BN_CTX_end(ctx);
dfeab068 RE	154	return(1);
dfeab068 RE	155	}
d02b48c6	156
dfeab068 RE	157	/* We want the remainder
	158	* Given input of ABCDEF / ab
	159	* we need multiply ABCDEF by 3 digests of the reciprocal of ab
	160	*
	161	*/
d02b48c6	162
8dea52fa BM	163	/* i := max(BN_num_bits(m), 2BN_num_bits(N)) /
8dea52fa BM	164	i=BN_num_bits(m);
63933136 AP	165	j=recp->num_bits<<1;
63933136 AP	166	if (j>i) i=j;
dfeab068	167
8dea52fa	168	/* Nr := round(2^i / N) */
dfeab068 RE	169	if (i != recp->shift)
dfeab068 RE	170	recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
78a0c1f1 BM	171	i,ctx); /* BN_reciprocal returns i, or -1 for an error */
78a0c1f1 BM	172	if (recp->shift == -1) goto err;
dfeab068	173
8dea52fa BM	174	/* d := \|round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))\|
	175	* = \|round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))\|
	176	* <= \|(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)\|
	177	* = \|m/N\|
	178	*/
	179	if (!BN_rshift(a,m,recp->num_bits)) goto err;
dfeab068	180	if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
8dea52fa	181	if (!BN_rshift(d,b,i-recp->num_bits)) goto err;
dfeab068	182	d->neg=0;
8dea52fa	183
dfeab068 RE	184	if (!BN_mul(b,&(recp->N),d,ctx)) goto err;
	185	if (!BN_usub(r,m,b)) goto err;
	186	r->neg=0;
	187
dfeab068	188	#if 1
63933136	189	j=0;
dfeab068	190	while (BN_ucmp(r,&(recp->N)) >= 0)
d02b48c6 RE	191	{
	192	if (j++ > 2)
	193	{
aa4ce731	194	BNerr(BN_F_BN_DIV_RECP,BN_R_BAD_RECIPROCAL);
d02b48c6 RE	195	goto err;
d02b48c6 RE	196	}
dfeab068 RE	197	if (!BN_usub(r,r,&(recp->N))) goto err;
dfeab068 RE	198	if (!BN_add_word(d,1)) goto err;
d02b48c6	199	}
dfeab068	200	#endif
d02b48c6	201
dfeab068 RE	202	r->neg=BN_is_zero(r)?0:m->neg;
dfeab068 RE	203	d->neg=m->neg^recp->N.neg;
d02b48c6 RE	204	ret=1;
d02b48c6 RE	205	err:
9b141126	206	BN_CTX_end(ctx);
8215e7a9 NL	207	bn_check_top(dv);
8215e7a9 NL	208	bn_check_top(rem);
d02b48c6	209	return(ret);
dfeab068	210	}
d02b48c6	211
dfeab068 RE	212	/* len is the expected size of the result
	213	* We actually calculate with an extra word of precision, so
	214	* we can do faster division if the remainder is not required.
	215	*/
78a0c1f1	216	/* r := 2^len / m */
4d6e1e4f	217	int BN_reciprocal(BIGNUM r, const BIGNUM m, size_t len, BN_CTX *ctx)
d02b48c6	218	{
dfeab068	219	int ret= -1;
c86f2054	220	BIGNUM *t;
d02b48c6	221
c86f2054 GT	222	BN_CTX_start(ctx);
c86f2054 GT	223	if((t = BN_CTX_get(ctx)) == NULL) goto err;
d02b48c6	224
c86f2054	225	if (!BN_set_bit(t,len)) goto err;
d02b48c6	226
c86f2054	227	if (!BN_div(r,NULL,t,m,ctx)) goto err;
8dea52fa	228
dfeab068	229	ret=len;
d02b48c6	230	err:
d870740c	231	bn_check_top(r);
c86f2054	232	BN_CTX_end(ctx);
d02b48c6 RE	233	return(ret);
d02b48c6 RE	234	}