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

/* crypto/bn/bn_mont.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.]
 */

/*
 * Details about Montgomery multiplication algorithms can be found at
 * http://security.ece.orst.edu/publications.html, e.g.
 * http://security.ece.orst.edu/koc/papers/j37acmon.pdf and
 * sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
 */

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

#define MONT_WORD /* use the faster word-based algorithm */

int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
			  BN_MONT_CTX *mont, BN_CTX *ctx)
	{
	BIGNUM *tmp;
	int ret=0;

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

	bn_check_top(tmp);
	if (a == b)
		{
		if (!BN_sqr(tmp,a,ctx)) goto err;
		}
	else
		{
		if (!BN_mul(tmp,a,b,ctx)) goto err;
		}
	/* reduce from aRR to aR */
	if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
	ret=1;
err:
	BN_CTX_end(ctx);
	return(ret);
	}

int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
	     BN_CTX *ctx)
	{
	int retn=0;

#ifdef MONT_WORD
	BIGNUM *n,*r;
	BN_ULONG *ap,*np,*rp,n0,v,*nrp;
	int al,nl,max,i,x,ri;

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

	if (!BN_copy(r,a)) goto err;
	n= &(mont->N);

	ap=a->d;
	/* mont->ri is the size of mont->N in bits (rounded up
	   to the word size) */
	al=ri=mont->ri/BN_BITS2;
	
	nl=n->top;
	if ((al == 0) || (nl == 0)) { r->top=0; return(1); }

	max=(nl+al+1); /* allow for overflow (no?) XXX */
	if (bn_wexpand(r,max) == NULL) goto err;
	if (bn_wexpand(ret,max) == NULL) goto err;

	r->neg=a->neg^n->neg;
	np=n->d;
	rp=r->d;
	nrp= &(r->d[nl]);

	/* clear the top words of T */
#if 1
	for (i=r->top; i<max; i++) /* memset? XXX */
		r->d[i]=0;
#else
	memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG)); 
#endif

	r->top=max;
	n0=mont->n0;

#ifdef BN_COUNT
	fprintf(stderr,"word BN_from_montgomery %d * %d\n",nl,nl);
#endif
	for (i=0; i<nl; i++)
		{
#ifdef __TANDEM
                {
                   long long t1;
                   long long t2;
                   long long t3;
                   t1 = rp[0] * (n0 & 0177777);
                   t2 = 037777600000l;
                   t2 = n0 & t2;
                   t3 = rp[0] & 0177777;
                   t2 = (t3 * t2) & BN_MASK2;
                   t1 = t1 + t2;
                   v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
                }
#else
		v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
#endif
		nrp++;
		rp++;
		if (((nrp[-1]+=v)&BN_MASK2) >= v)
			continue;
		else
			{
			if (((++nrp[0])&BN_MASK2) != 0) continue;
			if (((++nrp[1])&BN_MASK2) != 0) continue;
			for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
			}
		}
	bn_fix_top(r);
	
	/* mont->ri will be a multiple of the word size */
#if 0
	BN_rshift(ret,r,mont->ri);
#else
	ret->neg = r->neg;
	x=ri;
	rp=ret->d;
	ap= &(r->d[x]);
	if (r->top < x)
		al=0;
	else
		al=r->top-x;
	ret->top=al;
	al-=4;
	for (i=0; i<al; i+=4)
		{
		BN_ULONG t1,t2,t3,t4;
		
		t1=ap[i+0];
		t2=ap[i+1];
		t3=ap[i+2];
		t4=ap[i+3];
		rp[i+0]=t1;
		rp[i+1]=t2;
		rp[i+2]=t3;
		rp[i+3]=t4;
		}
	al+=4;
	for (; i<al; i++)
		rp[i]=ap[i];
#endif
#else /* !MONT_WORD */ 
	BIGNUM *t1,*t2;

	BN_CTX_start(ctx);
	t1 = BN_CTX_get(ctx);
	t2 = BN_CTX_get(ctx);
	if (t1 == NULL || t2 == NULL) goto err;
	
	if (!BN_copy(t1,a)) goto err;
	BN_mask_bits(t1,mont->ri);

	if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err;
	BN_mask_bits(t2,mont->ri);

	if (!BN_mul(t1,t2,&mont->N,ctx)) goto err;
	if (!BN_add(t2,a,t1)) goto err;
	if (!BN_rshift(ret,t2,mont->ri)) goto err;
#endif /* MONT_WORD */

	if (BN_ucmp(ret, &(mont->N)) >= 0)
		{
		if (!BN_usub(ret,ret,&(mont->N))) goto err;
		}
	retn=1;
 err:
	BN_CTX_end(ctx);
	return(retn);
	}

BN_MONT_CTX *BN_MONT_CTX_new(void)
	{
	BN_MONT_CTX *ret;

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

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

void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
	{
	ctx->ri=0;
	BN_init(&(ctx->RR));
	BN_init(&(ctx->N));
	BN_init(&(ctx->Ni));
	ctx->flags=0;
	}

void BN_MONT_CTX_free(BN_MONT_CTX *mont)
	{
	if(mont == NULL)
	    return;

	BN_free(&(mont->RR));
	BN_free(&(mont->N));
	BN_free(&(mont->Ni));
	if (mont->flags & BN_FLG_MALLOCED)
		OPENSSL_free(mont);
	}

int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
	{
	BIGNUM Ri,*R;

	BN_init(&Ri);
	R= &(mont->RR);					/* grab RR as a temp */
	BN_copy(&(mont->N),mod);			/* Set N */
	mont->N.neg = 0;

#ifdef MONT_WORD
		{
		BIGNUM tmod;
		BN_ULONG buf[2];

		mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
		if (!(BN_zero(R))) goto err;
		if (!(BN_set_bit(R,BN_BITS2))) goto err;	/* R */

		buf[0]=mod->d[0]; /* tmod = N mod word size */
		buf[1]=0;
		tmod.d=buf;
		tmod.top=1;
		tmod.dmax=2;
		tmod.neg=0;
							/* Ri = R^-1 mod N*/
		if ((BN_mod_inverse(&Ri,R,&tmod,ctx)) == NULL)
			goto err;
		if (!BN_lshift(&Ri,&Ri,BN_BITS2)) goto err; /* R*Ri */
		if (!BN_is_zero(&Ri))
			{
			if (!BN_sub_word(&Ri,1)) goto err;
			}
		else /* if N mod word size == 1 */
			{
			if (!BN_set_word(&Ri,BN_MASK2)) goto err;  /* Ri-- (mod word size) */
			}
		if (!BN_div(&Ri,NULL,&Ri,&tmod,ctx)) goto err;
		/* Ni = (R*Ri-1)/N,
		 * keep only least significant word: */
		mont->n0 = (Ri.top > 0) ? Ri.d[0] : 0;
		BN_free(&Ri);
		}
#else /* !MONT_WORD */
		{ /* bignum version */
		mont->ri=BN_num_bits(&mont->N);
		if (!BN_zero(R)) goto err;
		if (!BN_set_bit(R,mont->ri)) goto err;  /* R = 2^ri */
		                                        /* Ri = R^-1 mod N*/
		if ((BN_mod_inverse(&Ri,R,&mont->N,ctx)) == NULL)
			goto err;
		if (!BN_lshift(&Ri,&Ri,mont->ri)) goto err; /* R*Ri */
		if (!BN_sub_word(&Ri,1)) goto err;
							/* Ni = (R*Ri-1) / N */
		if (!BN_div(&(mont->Ni),NULL,&Ri,&mont->N,ctx)) goto err;
		BN_free(&Ri);
		}
#endif

	/* setup RR for conversions */
	if (!BN_zero(&(mont->RR))) goto err;
	if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err;
	if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err;

	return(1);
err:
	return(0);
	}

BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from)
	{
	if (to == from) return(to);

	if (!BN_copy(&(to->RR),&(from->RR))) return NULL;
	if (!BN_copy(&(to->N),&(from->N))) return NULL;
	if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL;
	to->ri=from->ri;
	to->n0=from->n0;
	return(to);
	}
Commit	Line	Data
d02b48c6	1	/* crypto/bn/bn_mont.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
1b3b0a54	59	/*
b99b1107 BM	60	* Details about Montgomery multiplication algorithms can be found at
	61	* http://security.ece.orst.edu/publications.html, e.g.
	62	* http://security.ece.orst.edu/koc/papers/j37acmon.pdf and
	63	* sections 3.8 and 4.2 in http://security.ece.orst.edu/koc/papers/r01rsasw.pdf
1b3b0a54 RE	64	*/
1b3b0a54 RE	65
d02b48c6 RE	66	#include <stdio.h>
	67	#include "cryptlib.h"
	68	#include "bn_lcl.h"
	69
6535eb17 UM	70	#define MONT_WORD /* use the faster word-based algorithm */
6535eb17 UM	71
020fc820	72	int BN_mod_mul_montgomery(BIGNUM r, const BIGNUM a, const BIGNUM *b,
84c15db5	73	BN_MONT_CTX mont, BN_CTX ctx)
d02b48c6	74	{
757e392d	75	BIGNUM *tmp;
0b8fa44e	76	int ret=0;
dfeab068	77
9b141126 UM	78	BN_CTX_start(ctx);
9b141126 UM	79	tmp = BN_CTX_get(ctx);
e1a8ac49	80	if (tmp == NULL) goto err;
d02b48c6	81
dfeab068	82	bn_check_top(tmp);
d02b48c6 RE	83	if (a == b)
	84	{
	85	if (!BN_sqr(tmp,a,ctx)) goto err;
	86	}
	87	else
	88	{
dfeab068	89	if (!BN_mul(tmp,a,b,ctx)) goto err;
d02b48c6 RE	90	}
	91	/* reduce from aRR to aR */
	92	if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
0b8fa44e	93	ret=1;
d02b48c6	94	err:
0b8fa44e UM	95	BN_CTX_end(ctx);
0b8fa44e UM	96	return(ret);
d02b48c6 RE	97	}
d02b48c6 RE	98
cbd48ba6	99	int BN_from_montgomery(BIGNUM ret, const BIGNUM a, BN_MONT_CTX *mont,
6b691a5c	100	BN_CTX *ctx)
d02b48c6	101	{
e93f9a32	102	int retn=0;
d02b48c6	103
6535eb17 UM	104	#ifdef MONT_WORD
	105	BIGNUM n,r;
	106	BN_ULONG ap,np,rp,n0,v,nrp;
	107	int al,nl,max,i,x,ri;
d02b48c6	108
6535eb17 UM	109	BN_CTX_start(ctx);
6535eb17 UM	110	if ((r = BN_CTX_get(ctx)) == NULL) goto err;
d02b48c6	111
6535eb17 UM	112	if (!BN_copy(r,a)) goto err;
6535eb17 UM	113	n= &(mont->N);
d02b48c6	114
6535eb17 UM	115	ap=a->d;
	116	/* mont->ri is the size of mont->N in bits (rounded up
	117	to the word size) */
	118	al=ri=mont->ri/BN_BITS2;
	119
	120	nl=n->top;
	121	if ((al == 0) \|\| (nl == 0)) { r->top=0; return(1); }
d02b48c6	122
6535eb17 UM	123	max=(nl+al+1); /* allow for overflow (no?) XXX */
	124	if (bn_wexpand(r,max) == NULL) goto err;
	125	if (bn_wexpand(ret,max) == NULL) goto err;
d02b48c6	126
6535eb17 UM	127	r->neg=a->neg^n->neg;
	128	np=n->d;
	129	rp=r->d;
	130	nrp= &(r->d[nl]);
d02b48c6	131
6535eb17	132	/* clear the top words of T */
58964a49	133	#if 1
6535eb17 UM	134	for (i=r->top; i<max; i++) /* memset? XXX */
6535eb17 UM	135	r->d[i]=0;
58964a49	136	#else
6535eb17	137	memset(&(r->d[r->top]),0,(max-r->top)*sizeof(BN_ULONG));
58964a49	138	#endif
d02b48c6	139
6535eb17 UM	140	r->top=max;
6535eb17 UM	141	n0=mont->n0;
d02b48c6	142
dfeab068	143	#ifdef BN_COUNT
cbd48ba6	144	fprintf(stderr,"word BN_from_montgomery %d * %d\n",nl,nl);
dfeab068	145	#endif
6535eb17 UM	146	for (i=0; i<nl; i++)
6535eb17 UM	147	{
2d978cbd DSH	148	#ifdef __TANDEM
	149	{
	150	long long t1;
	151	long long t2;
	152	long long t3;
	153	t1 = rp[0] * (n0 & 0177777);
	154	t2 = 037777600000l;
	155	t2 = n0 & t2;
	156	t3 = rp[0] & 0177777;
	157	t2 = (t3 * t2) & BN_MASK2;
	158	t1 = t1 + t2;
	159	v=bn_mul_add_words(rp,np,nl,(BN_ULONG) t1);
	160	}
	161	#else
6535eb17	162	v=bn_mul_add_words(rp,np,nl,(rp[0]*n0)&BN_MASK2);
2d978cbd	163	#endif
6535eb17 UM	164	nrp++;
	165	rp++;
	166	if (((nrp[-1]+=v)&BN_MASK2) >= v)
	167	continue;
	168	else
58964a49	169	{
6535eb17 UM	170	if (((++nrp[0])&BN_MASK2) != 0) continue;
	171	if (((++nrp[1])&BN_MASK2) != 0) continue;
	172	for (x=2; (((++nrp[x])&BN_MASK2) == 0); x++) ;
58964a49	173	}
6535eb17 UM	174	}
	175	bn_fix_top(r);
	176
	177	/* mont->ri will be a multiple of the word size */
dfeab068	178	#if 0
6535eb17	179	BN_rshift(ret,r,mont->ri);
dfeab068	180	#else
1d84fd64	181	ret->neg = r->neg;
6535eb17 UM	182	x=ri;
	183	rp=ret->d;
	184	ap= &(r->d[x]);
	185	if (r->top < x)
	186	al=0;
	187	else
	188	al=r->top-x;
	189	ret->top=al;
	190	al-=4;
	191	for (i=0; i<al; i+=4)
	192	{
	193	BN_ULONG t1,t2,t3,t4;
	194
	195	t1=ap[i+0];
	196	t2=ap[i+1];
	197	t3=ap[i+2];
	198	t4=ap[i+3];
	199	rp[i+0]=t1;
	200	rp[i+1]=t2;
	201	rp[i+2]=t3;
	202	rp[i+3]=t4;
	203	}
	204	al+=4;
	205	for (; i<al; i++)
	206	rp[i]=ap[i];
58964a49	207	#endif
6535eb17 UM	208	#else /* !MONT_WORD */
6535eb17 UM	209	BIGNUM t1,t2;
58964a49	210
6535eb17 UM	211	BN_CTX_start(ctx);
	212	t1 = BN_CTX_get(ctx);
	213	t2 = BN_CTX_get(ctx);
	214	if (t1 == NULL \|\| t2 == NULL) goto err;
	215
	216	if (!BN_copy(t1,a)) goto err;
	217	BN_mask_bits(t1,mont->ri);
	218
	219	if (!BN_mul(t2,t1,&mont->Ni,ctx)) goto err;
	220	BN_mask_bits(t2,mont->ri);
	221
	222	if (!BN_mul(t1,t2,&mont->N,ctx)) goto err;
	223	if (!BN_add(t2,a,t1)) goto err;
9cdf87f1	224	if (!BN_rshift(ret,t2,mont->ri)) goto err;
6535eb17 UM	225	#endif /* MONT_WORD */
	226
	227	if (BN_ucmp(ret, &(mont->N)) >= 0)
58964a49	228	{
8dea52fa	229	if (!BN_usub(ret,ret,&(mont->N))) goto err;
dfeab068	230	}
6535eb17	231	retn=1;
e93f9a32	232	err:
9b141126	233	BN_CTX_end(ctx);
e93f9a32	234	return(retn);
dfeab068	235	}
d02b48c6	236
6b691a5c	237	BN_MONT_CTX *BN_MONT_CTX_new(void)
d02b48c6 RE	238	{
	239	BN_MONT_CTX *ret;
	240
26a3a48d	241	if ((ret=(BN_MONT_CTX *)OPENSSL_malloc(sizeof(BN_MONT_CTX))) == NULL)
d02b48c6	242	return(NULL);
dfeab068 RE	243
	244	BN_MONT_CTX_init(ret);
	245	ret->flags=BN_FLG_MALLOCED;
d02b48c6 RE	246	return(ret);
	247	}
	248
6b691a5c	249	void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
dfeab068	250	{
dfeab068 RE	251	ctx->ri=0;
	252	BN_init(&(ctx->RR));
	253	BN_init(&(ctx->N));
	254	BN_init(&(ctx->Ni));
	255	ctx->flags=0;
	256	}
	257
6b691a5c	258	void BN_MONT_CTX_free(BN_MONT_CTX *mont)
d02b48c6	259	{
e03ddfae BL	260	if(mont == NULL)
	261	return;
	262
dfeab068 RE	263	BN_free(&(mont->RR));
	264	BN_free(&(mont->N));
	265	BN_free(&(mont->Ni));
	266	if (mont->flags & BN_FLG_MALLOCED)
26a3a48d	267	OPENSSL_free(mont);
d02b48c6 RE	268	}
d02b48c6 RE	269
84c15db5	270	int BN_MONT_CTX_set(BN_MONT_CTX mont, const BIGNUM mod, BN_CTX *ctx)
d02b48c6	271	{
dfeab068 RE	272	BIGNUM Ri,*R;
	273
	274	BN_init(&Ri);
	275	R= &(mont->RR); /* grab RR as a temp */
	276	BN_copy(&(mont->N),mod); /* Set N */
8dea52fa	277	mont->N.neg = 0;
dfeab068	278
6535eb17	279	#ifdef MONT_WORD
dfeab068 RE	280	{
	281	BIGNUM tmod;
	282	BN_ULONG buf[2];
	283
dfeab068	284	mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
9cdf87f1 RL	285	if (!(BN_zero(R))) goto err;
9cdf87f1 RL	286	if (!(BN_set_bit(R,BN_BITS2))) goto err; /* R */
dfeab068	287
e93f9a32	288	buf[0]=mod->d[0]; /* tmod = N mod word size */
dfeab068 RE	289	buf[1]=0;
	290	tmod.d=buf;
	291	tmod.top=1;
2d978cbd	292	tmod.dmax=2;
8dea52fa	293	tmod.neg=0;
e93f9a32	294	/* Ri = R^-1 mod N*/
dfeab068 RE	295	if ((BN_mod_inverse(&Ri,R,&tmod,ctx)) == NULL)
dfeab068 RE	296	goto err;
8dea52fa	297	if (!BN_lshift(&Ri,&Ri,BN_BITS2)) goto err; /* RRi /
dfeab068	298	if (!BN_is_zero(&Ri))
8dea52fa BM	299	{
	300	if (!BN_sub_word(&Ri,1)) goto err;
	301	}
e93f9a32	302	else /* if N mod word size == 1 */
8dea52fa BM	303	{
	304	if (!BN_set_word(&Ri,BN_MASK2)) goto err; /* Ri-- (mod word size) */
	305	}
	306	if (!BN_div(&Ri,NULL,&Ri,&tmod,ctx)) goto err;
	307	/* Ni = (R*Ri-1)/N,
	308	* keep only least significant word: */
	309	mont->n0 = (Ri.top > 0) ? Ri.d[0] : 0;
dfeab068	310	BN_free(&Ri);
dfeab068	311	}
6535eb17	312	#else /* !MONT_WORD */
e93f9a32	313	{ /* bignum version */
8dea52fa BM	314	mont->ri=BN_num_bits(&mont->N);
	315	if (!BN_zero(R)) goto err;
	316	if (!BN_set_bit(R,mont->ri)) goto err; /* R = 2^ri */
	317	/* Ri = R^-1 mod N*/
	318	if ((BN_mod_inverse(&Ri,R,&mont->N,ctx)) == NULL)
dfeab068	319	goto err;
8dea52fa BM	320	if (!BN_lshift(&Ri,&Ri,mont->ri)) goto err; /* RRi /
8dea52fa BM	321	if (!BN_sub_word(&Ri,1)) goto err;
e93f9a32	322	/* Ni = (RRi-1) / N /
8dea52fa	323	if (!BN_div(&(mont->Ni),NULL,&Ri,&mont->N,ctx)) goto err;
dfeab068 RE	324	BN_free(&Ri);
dfeab068 RE	325	}
d02b48c6 RE	326	#endif
	327
	328	/* setup RR for conversions */
8dea52fa BM	329	if (!BN_zero(&(mont->RR))) goto err;
	330	if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err;
	331	if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err;
d02b48c6 RE	332
	333	return(1);
	334	err:
	335	return(0);
	336	}
	337
6b691a5c	338	BN_MONT_CTX BN_MONT_CTX_copy(BN_MONT_CTX to, BN_MONT_CTX *from)
dfeab068 RE	339	{
	340	if (to == from) return(to);
	341
156e8557 BM	342	if (!BN_copy(&(to->RR),&(from->RR))) return NULL;
	343	if (!BN_copy(&(to->N),&(from->N))) return NULL;
	344	if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL;
dfeab068 RE	345	to->ri=from->ri;
	346	to->n0=from->n0;
	347	return(to);
	348	}
	349