/* -*-c-*-
*
- * $Id: mpbarrett.c,v 1.8 2001/06/16 13:00:20 mdw Exp $
+ * $Id$
*
* Barrett modular reduction
*
* (c) 1999 Straylight/Edgeware
*/
-/*----- Licensing notice --------------------------------------------------*
+/*----- Licensing notice --------------------------------------------------*
*
* This file is part of Catacomb.
*
* it under the terms of the GNU Library General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
- *
+ *
* Catacomb is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Library General Public License for more details.
- *
+ *
* You should have received a copy of the GNU Library General Public
* License along with Catacomb; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
-/*----- Revision history --------------------------------------------------*
- *
- * $Log: mpbarrett.c,v $
- * Revision 1.8 2001/06/16 13:00:20 mdw
- * Use the generic exponentiation functions.
- *
- * Revision 1.7 2001/04/19 18:25:26 mdw
- * Use sliding-window exponentiation.
- *
- * Revision 1.6 2000/10/08 12:03:44 mdw
- * (mpbarrett_reduce): Cope with negative numbers.
- *
- * Revision 1.5 2000/07/29 17:04:33 mdw
- * Change to use left-to-right bitwise exponentiation. This will improve
- * performance when the base is small.
- *
- * Revision 1.4 2000/06/17 11:45:09 mdw
- * Major memory management overhaul. Added arena support. Use the secure
- * arena for secret integers. Replace and improve the MP management macros
- * (e.g., replace MP_MODIFY by MP_DEST).
- *
- * Revision 1.3 1999/12/12 15:08:52 mdw
- * Don't bother shifting %$q$% in @mpbarrett_reduce@, just skip the least
- * significant digits.
- *
- * Revision 1.2 1999/12/11 01:50:56 mdw
- * Improve initialization slightly.
- *
- * Revision 1.1 1999/12/10 23:21:59 mdw
- * Barrett reduction support: works with even moduli.
- *
- */
-
/*----- Header files ------------------------------------------------------*/
#include "mp.h"
#include "mpbarrett.h"
-#include "mpbarrett-exp.h"
/*----- Main code ---------------------------------------------------------*/
* @mp *m@ = modulus to work to
*
*
- * Returns: ---
+ * Returns: Zero on success, nonzero on error.
*
* Use: Initializes a Barrett reduction context ready for use.
*/
-void mpbarrett_create(mpbarrett *mb, mp *m)
+int mpbarrett_create(mpbarrett *mb, mp *m)
{
mp *b;
/* --- Validate the arguments --- */
- assert(((void)"Barrett modulus must be positive", (m->f & MP_NEG) == 0));
+ if (!MP_POSP(m))
+ return (-1);
/* --- Compute %$\mu$% --- */
b->vl[-1] = 1;
mp_div(&b, 0, b, m);
mb->mu = b;
+ return (0);
}
/* --- @mpbarrett_destroy@ --- *
m = MP_COPY(m);
if (d)
MP_DROP(d);
+ MP_DROP(q);
return (m);
}
}
mvl = m->v + k + 1;
r = mp_new(k + 1, (q->f | mb->m->f) & MP_BURN);
mpx_umul(r->v, r->vl, q->v + k + 1, q->vl, mb->m->v, mb->m->vl);
- MP_DEST(d, k + 1, r->f);
+ MP_DEST(d, k + 1, r->f | MP_UNDEF);
mpx_usub(d->v, d->vl, m->v, mvl, r->v, r->vl);
d->f = (m->f | r->f) & (MP_BURN | MP_NEG);
MP_DROP(r);
return (d);
}
-/* --- @mpbarrett_exp@ --- *
- *
- * Arguments: @mpbarrett *mb@ = pointer to Barrett reduction context
- * @mp *d@ = fake destination
- * @mp *a@ = base
- * @mp *e@ = exponent
- *
- * Returns: Result, %$a^e \bmod m$%.
- */
-
-mp *mpbarrett_exp(mpbarrett *mb, mp *d, mp *a, mp *e)
-{
- mp *x = MP_ONE;
- mp *spare = (e->f & MP_BURN) ? MP_NEWSEC : MP_NEW;
-
- MP_SHRINK(e);
- if (!MP_LEN(e))
- ;
- else if (MP_LEN(e) < EXP_THRESH)
- EXP_SIMPLE(x, a, e);
- else
- EXP_WINDOW(x, a, e);
- mp_drop(d);
- mp_drop(spare);
- return (x);
-}
-
/*----- Test rig ----------------------------------------------------------*/
#ifdef TEST_RIG
return (ok);
}
-static int vexp(dstr *v)
-{
- mp *m = *(mp **)v[0].buf;
- mp *a = *(mp **)v[1].buf;
- mp *b = *(mp **)v[2].buf;
- mp *r = *(mp **)v[3].buf;
- mp *mr;
- int ok = 1;
-
- mpbarrett mb;
- mpbarrett_create(&mb, m);
-
- mr = mpbarrett_exp(&mb, MP_NEW, a, b);
-
- if (!MP_EQ(mr, r)) {
- fputs("\n*** barrett modexp failed", stderr);
- fputs("\n m = ", stderr); mp_writefile(m, stderr, 10);
- fputs("\n a = ", stderr); mp_writefile(a, stderr, 10);
- fputs("\n e = ", stderr); mp_writefile(b, stderr, 10);
- fputs("\n r = ", stderr); mp_writefile(r, stderr, 10);
- fputs("\nmr = ", stderr); mp_writefile(mr, stderr, 10);
- fputc('\n', stderr);
- ok = 0;
- }
-
- mp_drop(m);
- mp_drop(a);
- mp_drop(b);
- mp_drop(r);
- mp_drop(mr);
- mpbarrett_destroy(&mb);
- assert(mparena_count(MPARENA_GLOBAL) == 0);
- return ok;
-}
-
static test_chunk tests[] = {
{ "mpbarrett-reduce", vmod, { &type_mp, &type_mp, &type_mp, 0 } },
- { "mpbarrett-exp", vexp, { &type_mp, &type_mp, &type_mp, &type_mp, 0 } },
{ 0, 0, { 0 } }
};
projects / u / mdw / catacomb / blobdiff