93 lines
2.2 KiB
C
93 lines
2.2 KiB
C
|
/* mpi-mul.c - MPI functions
|
||
|
|
* Copyright (C) 1994, 1996, 1998, 2001, 2002,
|
||
|
|
* 2003 Free Software Foundation, Inc.
|
||
|
|
*
|
||
|
|
* This file is part of Libgcrypt.
|
||
|
|
*
|
||
|
|
* Note: This code is heavily based on the GNU MP Library.
|
||
|
|
* Actually it's the same code with only minor changes in the
|
||
|
|
* way the data is stored; this is to support the abstraction
|
||
|
|
* of an optional secure memory allocation which may be used
|
||
|
|
* to avoid revealing of sensitive data due to paging etc.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "mpi-internal.h"
|
||
|
|
|
||
|
|
void mpi_mul(MPI w, MPI u, MPI v)
|
||
|
|
{
|
||
|
|
mpi_size_t usize, vsize, wsize;
|
||
|
|
mpi_ptr_t up, vp, wp;
|
||
|
|
mpi_limb_t cy;
|
||
|
|
int usign, vsign, sign_product;
|
||
|
|
int assign_wp = 0;
|
||
|
|
mpi_ptr_t tmp_limb = NULL;
|
||
|
|
|
||
|
|
if (u->nlimbs < v->nlimbs) {
|
||
|
|
/* Swap U and V. */
|
||
|
|
usize = v->nlimbs;
|
||
|
|
usign = v->sign;
|
||
|
|
up = v->d;
|
||
|
|
vsize = u->nlimbs;
|
||
|
|
vsign = u->sign;
|
||
|
|
vp = u->d;
|
||
|
|
} else {
|
||
|
|
usize = u->nlimbs;
|
||
|
|
usign = u->sign;
|
||
|
|
up = u->d;
|
||
|
|
vsize = v->nlimbs;
|
||
|
|
vsign = v->sign;
|
||
|
|
vp = v->d;
|
||
|
|
}
|
||
|
|
sign_product = usign ^ vsign;
|
||
|
|
wp = w->d;
|
||
|
|
|
||
|
|
/* Ensure W has space enough to store the result. */
|
||
|
|
wsize = usize + vsize;
|
||
|
|
if (w->alloced < wsize) {
|
||
|
|
if (wp == up || wp == vp) {
|
||
|
|
wp = mpi_alloc_limb_space(wsize);
|
||
|
|
assign_wp = 1;
|
||
|
|
} else {
|
||
|
|
mpi_resize(w, wsize);
|
||
|
|
wp = w->d;
|
||
|
|
}
|
||
|
|
} else { /* Make U and V not overlap with W. */
|
||
|
|
if (wp == up) {
|
||
|
|
/* W and U are identical. Allocate temporary space for U. */
|
||
|
|
up = tmp_limb = mpi_alloc_limb_space(usize);
|
||
|
|
/* Is V identical too? Keep it identical with U. */
|
||
|
|
if (wp == vp)
|
||
|
|
vp = up;
|
||
|
|
/* Copy to the temporary space. */
|
||
|
|
MPN_COPY(up, wp, usize);
|
||
|
|
} else if (wp == vp) {
|
||
|
|
/* W and V are identical. Allocate temporary space for V. */
|
||
|
|
vp = tmp_limb = mpi_alloc_limb_space(vsize);
|
||
|
|
/* Copy to the temporary space. */
|
||
|
|
MPN_COPY(vp, wp, vsize);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
if (!vsize)
|
||
|
|
wsize = 0;
|
||
|
|
else {
|
||
|
|
mpihelp_mul(wp, up, usize, vp, vsize, &cy);
|
||
|
|
wsize -= cy ? 0:1;
|
||
|
|
}
|
||
|
|
|
||
|
|
if (assign_wp)
|
||
|
|
mpi_assign_limb_space(w, wp, wsize);
|
||
|
|
w->nlimbs = wsize;
|
||
|
|
w->sign = sign_product;
|
||
|
|
if (tmp_limb)
|
||
|
|
mpi_free_limb_space(tmp_limb);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(mpi_mul);
|
||
|
|
|
||
|
|
void mpi_mulm(MPI w, MPI u, MPI v, MPI m)
|
||
|
|
{
|
||
|
|
mpi_mul(w, u, v);
|
||
|
|
mpi_tdiv_r(w, w, m);
|
||
|
|
}
|
||
|
|
EXPORT_SYMBOL_GPL(mpi_mulm);
|