You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
234 lines
6.6 KiB
234 lines
6.6 KiB
/* 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, int 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);
|
|
}
|
|
|