mirror of
http://galexander.org/git/simplesshd.git
synced 2024-11-30 19:28:10 +00:00
85 lines
2.3 KiB
C
85 lines
2.3 KiB
C
#include <tommath.h>
|
|
#ifdef BN_S_MP_SQR_C
|
|
/* LibTomMath, multiple-precision integer library -- Tom St Denis
|
|
*
|
|
* LibTomMath is a library that provides multiple-precision
|
|
* integer arithmetic as well as number theoretic functionality.
|
|
*
|
|
* The library was designed directly after the MPI library by
|
|
* Michael Fromberger but has been written from scratch with
|
|
* additional optimizations in place.
|
|
*
|
|
* The library is free for all purposes without any express
|
|
* guarantee it works.
|
|
*
|
|
* Tom St Denis, tomstdenis@gmail.com, http://math.libtomcrypt.com
|
|
*/
|
|
|
|
/* low level squaring, b = a*a, HAC pp.596-597, Algorithm 14.16 */
|
|
int s_mp_sqr (mp_int * a, mp_int * b)
|
|
{
|
|
mp_int t;
|
|
int res, ix, iy, pa;
|
|
mp_word r;
|
|
mp_digit u, tmpx, *tmpt;
|
|
|
|
pa = a->used;
|
|
if ((res = mp_init_size (&t, 2*pa + 1)) != MP_OKAY) {
|
|
return res;
|
|
}
|
|
|
|
/* default used is maximum possible size */
|
|
t.used = 2*pa + 1;
|
|
|
|
for (ix = 0; ix < pa; ix++) {
|
|
/* first calculate the digit at 2*ix */
|
|
/* calculate double precision result */
|
|
r = ((mp_word) t.dp[2*ix]) +
|
|
((mp_word)a->dp[ix])*((mp_word)a->dp[ix]);
|
|
|
|
/* store lower part in result */
|
|
t.dp[ix+ix] = (mp_digit) (r & ((mp_word) MP_MASK));
|
|
|
|
/* get the carry */
|
|
u = (mp_digit)(r >> ((mp_word) DIGIT_BIT));
|
|
|
|
/* left hand side of A[ix] * A[iy] */
|
|
tmpx = a->dp[ix];
|
|
|
|
/* alias for where to store the results */
|
|
tmpt = t.dp + (2*ix + 1);
|
|
|
|
for (iy = ix + 1; iy < pa; iy++) {
|
|
/* first calculate the product */
|
|
r = ((mp_word)tmpx) * ((mp_word)a->dp[iy]);
|
|
|
|
/* now calculate the double precision result, note we use
|
|
* addition instead of *2 since it's easier to optimize
|
|
*/
|
|
r = ((mp_word) *tmpt) + r + r + ((mp_word) u);
|
|
|
|
/* store lower part */
|
|
*tmpt++ = (mp_digit) (r & ((mp_word) MP_MASK));
|
|
|
|
/* get carry */
|
|
u = (mp_digit)(r >> ((mp_word) DIGIT_BIT));
|
|
}
|
|
/* propagate upwards */
|
|
while (u != ((mp_digit) 0)) {
|
|
r = ((mp_word) *tmpt) + ((mp_word) u);
|
|
*tmpt++ = (mp_digit) (r & ((mp_word) MP_MASK));
|
|
u = (mp_digit)(r >> ((mp_word) DIGIT_BIT));
|
|
}
|
|
}
|
|
|
|
mp_clamp (&t);
|
|
mp_exch (&t, b);
|
|
mp_clear (&t);
|
|
return MP_OKAY;
|
|
}
|
|
#endif
|
|
|
|
/* $Source: /cvs/libtom/libtommath/bn_s_mp_sqr.c,v $ */
|
|
/* $Revision: 1.3 $ */
|
|
/* $Date: 2006/03/31 14:18:44 $ */
|