291 lines
8.3 KiB
C
291 lines
8.3 KiB
C
/* crypto/bn/bn_sqr.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"
|
|
|
|
/* r must not be a */
|
|
/*
|
|
* I've just gone over this and it is now %20 faster on x86 - eay - 27 Jun 96
|
|
*/
|
|
int BN_sqr(BIGNUM *r, const BIGNUM *a, BN_CTX *ctx)
|
|
{
|
|
int max, al;
|
|
int ret = 0;
|
|
BIGNUM *tmp, *rr;
|
|
|
|
#ifdef BN_COUNT
|
|
fprintf(stderr, "BN_sqr %d * %d\n", a->top, a->top);
|
|
#endif
|
|
bn_check_top(a);
|
|
|
|
al = a->top;
|
|
if (al <= 0) {
|
|
r->top = 0;
|
|
r->neg = 0;
|
|
return 1;
|
|
}
|
|
|
|
BN_CTX_start(ctx);
|
|
rr = (a != r) ? r : BN_CTX_get(ctx);
|
|
tmp = BN_CTX_get(ctx);
|
|
if (!rr || !tmp)
|
|
goto err;
|
|
|
|
max = 2 * al; /* Non-zero (from above) */
|
|
if (bn_wexpand(rr, max) == NULL)
|
|
goto err;
|
|
|
|
if (al == 4) {
|
|
#ifndef BN_SQR_COMBA
|
|
BN_ULONG t[8];
|
|
bn_sqr_normal(rr->d, a->d, 4, t);
|
|
#else
|
|
bn_sqr_comba4(rr->d, a->d);
|
|
#endif
|
|
} else if (al == 8) {
|
|
#ifndef BN_SQR_COMBA
|
|
BN_ULONG t[16];
|
|
bn_sqr_normal(rr->d, a->d, 8, t);
|
|
#else
|
|
bn_sqr_comba8(rr->d, a->d);
|
|
#endif
|
|
} else {
|
|
#if defined(BN_RECURSION)
|
|
if (al < BN_SQR_RECURSIVE_SIZE_NORMAL) {
|
|
BN_ULONG t[BN_SQR_RECURSIVE_SIZE_NORMAL * 2];
|
|
bn_sqr_normal(rr->d, a->d, al, t);
|
|
} else {
|
|
int j, k;
|
|
|
|
j = BN_num_bits_word((BN_ULONG)al);
|
|
j = 1 << (j - 1);
|
|
k = j + j;
|
|
if (al == j) {
|
|
if (bn_wexpand(tmp, k * 2) == NULL)
|
|
goto err;
|
|
bn_sqr_recursive(rr->d, a->d, al, tmp->d);
|
|
} else {
|
|
if (bn_wexpand(tmp, max) == NULL)
|
|
goto err;
|
|
bn_sqr_normal(rr->d, a->d, al, tmp->d);
|
|
}
|
|
}
|
|
#else
|
|
if (bn_wexpand(tmp, max) == NULL)
|
|
goto err;
|
|
bn_sqr_normal(rr->d, a->d, al, tmp->d);
|
|
#endif
|
|
}
|
|
|
|
rr->neg = 0;
|
|
/*
|
|
* If the most-significant half of the top word of 'a' is zero, then the
|
|
* square of 'a' will max-1 words.
|
|
*/
|
|
if (a->d[al - 1] == (a->d[al - 1] & BN_MASK2l))
|
|
rr->top = max - 1;
|
|
else
|
|
rr->top = max;
|
|
if (rr != r)
|
|
BN_copy(r, rr);
|
|
ret = 1;
|
|
err:
|
|
bn_check_top(rr);
|
|
bn_check_top(tmp);
|
|
BN_CTX_end(ctx);
|
|
return (ret);
|
|
}
|
|
|
|
/* tmp must have 2*n words */
|
|
void bn_sqr_normal(BN_ULONG *r, const BN_ULONG *a, int n, BN_ULONG *tmp)
|
|
{
|
|
int i, j, max;
|
|
const BN_ULONG *ap;
|
|
BN_ULONG *rp;
|
|
|
|
max = n * 2;
|
|
ap = a;
|
|
rp = r;
|
|
rp[0] = rp[max - 1] = 0;
|
|
rp++;
|
|
j = n;
|
|
|
|
if (--j > 0) {
|
|
ap++;
|
|
rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
|
|
rp += 2;
|
|
}
|
|
|
|
for (i = n - 2; i > 0; i--) {
|
|
j--;
|
|
ap++;
|
|
rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
|
|
rp += 2;
|
|
}
|
|
|
|
bn_add_words(r, r, r, max);
|
|
|
|
/* There will not be a carry */
|
|
|
|
bn_sqr_words(tmp, a, n);
|
|
|
|
bn_add_words(r, r, tmp, max);
|
|
}
|
|
|
|
#ifdef BN_RECURSION
|
|
/*-
|
|
* r is 2*n words in size,
|
|
* a and b are both n words in size. (There's not actually a 'b' here ...)
|
|
* n must be a power of 2.
|
|
* We multiply and return the result.
|
|
* t must be 2*n words in size
|
|
* We calculate
|
|
* a[0]*b[0]
|
|
* a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
|
|
* a[1]*b[1]
|
|
*/
|
|
void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
|
|
{
|
|
int n = n2 / 2;
|
|
int zero, c1;
|
|
BN_ULONG ln, lo, *p;
|
|
|
|
# ifdef BN_COUNT
|
|
fprintf(stderr, " bn_sqr_recursive %d * %d\n", n2, n2);
|
|
# endif
|
|
if (n2 == 4) {
|
|
# ifndef BN_SQR_COMBA
|
|
bn_sqr_normal(r, a, 4, t);
|
|
# else
|
|
bn_sqr_comba4(r, a);
|
|
# endif
|
|
return;
|
|
} else if (n2 == 8) {
|
|
# ifndef BN_SQR_COMBA
|
|
bn_sqr_normal(r, a, 8, t);
|
|
# else
|
|
bn_sqr_comba8(r, a);
|
|
# endif
|
|
return;
|
|
}
|
|
if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
|
|
bn_sqr_normal(r, a, n2, t);
|
|
return;
|
|
}
|
|
/* r=(a[0]-a[1])*(a[1]-a[0]) */
|
|
c1 = bn_cmp_words(a, &(a[n]), n);
|
|
zero = 0;
|
|
if (c1 > 0)
|
|
bn_sub_words(t, a, &(a[n]), n);
|
|
else if (c1 < 0)
|
|
bn_sub_words(t, &(a[n]), a, n);
|
|
else
|
|
zero = 1;
|
|
|
|
/* The result will always be negative unless it is zero */
|
|
p = &(t[n2 * 2]);
|
|
|
|
if (!zero)
|
|
bn_sqr_recursive(&(t[n2]), t, n, p);
|
|
else
|
|
memset(&(t[n2]), 0, n2 * sizeof(BN_ULONG));
|
|
bn_sqr_recursive(r, a, n, p);
|
|
bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
|
|
|
|
/*-
|
|
* t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
|
|
* r[10] holds (a[0]*b[0])
|
|
* r[32] holds (b[1]*b[1])
|
|
*/
|
|
|
|
c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
|
|
|
|
/* t[32] is negative */
|
|
c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
|
|
|
|
/*-
|
|
* t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
|
|
* r[10] holds (a[0]*a[0])
|
|
* r[32] holds (a[1]*a[1])
|
|
* c1 holds the carry bits
|
|
*/
|
|
c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
|
|
if (c1) {
|
|
p = &(r[n + n2]);
|
|
lo = *p;
|
|
ln = (lo + c1) & BN_MASK2;
|
|
*p = ln;
|
|
|
|
/*
|
|
* The overflow will stop before we over write words we should not
|
|
* overwrite
|
|
*/
|
|
if (ln < (BN_ULONG)c1) {
|
|
do {
|
|
p++;
|
|
lo = *p;
|
|
ln = (lo + 1) & BN_MASK2;
|
|
*p = ln;
|
|
} while (ln == 0);
|
|
}
|
|
}
|
|
}
|
|
#endif
|