+++ /dev/null
-/* -*-c-*-
- *
- * $Id$
- *
- * Prime fields with Montgomery arithmetic
- *
- * (c) 2001 Straylight/Edgeware
- */
-
-/*----- Licensing notice --------------------------------------------------*
- *
- * This file is part of Catacomb.
- *
- * Catacomb is free software; you can redistribute it and/or modify
- * 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.
- */
-
-/*----- Header files ------------------------------------------------------*/
-
-#include <mLib/sub.h>
-
-#include "field.h"
-#include "mprand.h"
-#include "field-guts.h"
-
-/*----- Main code ---------------------------------------------------------*/
-
-/* --- Field operations --- */
-
-static void fdestroy(field *ff) {
- fctx_prime *f = (fctx_prime *)ff;
- mpmont_destroy(&f->mm);
- DESTROY(f);
-}
-
-static mp *frand(field *ff, mp *d, grand *r) {
- fctx_prime *f = (fctx_prime *)ff;
- return (mprand_range(d, f->mm.m, r, 0));
-}
-
-static mp *fin(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff;
- mp_div(0, &d, x, f->mm.m);
- return (mpmont_mul(&f->mm, d, d, f->mm.r2));
-}
-
-static mp *fout(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff;
- return (mpmont_reduce(&f->mm, d, x));
-}
-
-static int fzerop(field *ff, mp *x) { return (MP_ZEROP(x)); }
-
-static mp *fneg(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff;
- return (mp_sub(d, f->mm.m, x));
-}
-
-static mp *fadd(field *ff, mp *d, mp *x, mp *y) {
- fctx_prime *f = (fctx_prime *)ff; d = mp_add(d, x, y);
- if (MP_NEGP(d)) d = mp_add(d, d, f->mm.m);
- else if (MP_CMP(d, >, f->mm.m)) d = mp_sub(d, d, f->mm.m);
- return (d);
-}
-
-static mp *fsub(field *ff, mp *d, mp *x, mp *y) {
- fctx_prime *f = (fctx_prime *)ff; d = mp_sub(d, x, y);
- if (MP_NEGP(d)) d = mp_add(d, d, f->mm.m);
- else if (MP_CMP(d, >, f->mm.m)) d = mp_sub(d, d, f->mm.m);
- return (d);
-}
-
-static mp *fmul(field *ff, mp *d, mp *x, mp *y) {
- fctx_prime *f = (fctx_prime *)ff;
- return (mpmont_mul(&f->mm, d, x, y));
-}
-
-static mp *fsqr(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff; d = mp_sqr(d, x);
- return (mpmont_reduce(&f->mm, d, d));
-}
-
-static mp *finv(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff; d = mpmont_reduce(&f->mm, d, x);
- d = mp_modinv(d, d, f->mm.m); return (mpmont_mul(&f->mm, d, d, f->mm.r2));
-}
-
-static mp *freduce(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff;
- mp_div(0, &d, x, f->mm.m);
- return (d);
-}
-
-static mp *fsqrt(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff; d = mpmont_reduce(&f->mm, d, x);
- d = mp_modsqrt(d, d, f->mm.m); if (!d) return (d);
- return (mpmont_mul(&f->mm, d, d, f->mm.r2));
-}
-
-static mp *fdbl(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff; d = mp_lsl(d, x, 1);
- if (MP_CMP(d, >=, f->mm.m)) d = mp_sub(d, d, f->mm.m);
- return (d);
-}
-
-static mp *ftpl(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff; MP_DEST(d, MP_LEN(x) + 1, x->f);
- MPX_UMULN(d->v, d->vl, x->v, x->vl, 3); d->f &= ~MP_UNDEF;
- while (MP_CMP(d, >=, f->mm.m)) d = mp_sub(d, d, f->mm.m);
- return (d);
-}
-
-static mp *fqdl(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff; d = mp_lsl(d, x, 2);
- while (MP_CMP(d, >=, f->mm.m)) d = mp_sub(d, d, f->mm.m);
- return (d);
-}
-
-static mp *fhlv(field *ff, mp *d, mp *x) {
- fctx_prime *f = (fctx_prime *)ff;
- if (MP_ZEROP(x)) { MP_COPY(x); MP_DROP(d); return (x); }
- if (x->v[0] & 1) { d = mp_add(d, x, f->mm.m); x = d; }
- return (mp_lsr(d, x, 1));
-}
-
-/* --- Field operations table --- */
-
-static const field_ops fops = {
- FTY_PRIME, "prime",
- fdestroy, frand, field_stdsamep,
- fin, fout,
- fzerop, fneg, fadd, fsub, fmul, fsqr, finv, freduce, fsqrt,
- 0,
- fdbl, ftpl, fqdl, fhlv
-};
-
-/* --- @field_prime@ --- *
- *
- * Arguments: @mp *p@ = the characteristic of the field
- *
- * Returns: A pointer to the field or null.
- *
- * Use: Creates a field structure for a prime field of size %$p$%,
- * using Montgomery reduction for arithmetic.
- */
-
-field *field_prime(mp *p)
-{
- fctx_prime *f;
-
- f = CREATE(fctx_prime);
- f->f.ops = &fops;
- if (mpmont_create(&f->mm, p)) {
- DESTROY(f);
- return (0);
- }
- f->f.zero = MP_ZERO;
- f->f.one = f->mm.r;
- f->f.m = f->mm.m;
- f->f.nbits = mp_bits(p);
- f->f.noctets = (f->f.nbits + 7) >> 3;
- f->f.q = f->mm.m;
- return (&f->f);
-}
-
-/*----- That's all, folks -------------------------------------------------*/
projects / u / mdw / catacomb / blobdiff