3 * Binary fields with polynomial basis representation
5 * (c) 2004 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of Catacomb.
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
33 #include "field-guts.h"
36 /*----- Polynomial basis --------------------------------------------------*/
38 /* --- Field operations --- */
40 static void fdestroy(field *ff) {
41 fctx_binpoly *f = (fctx_binpoly *)ff;
42 gfreduce_destroy(&f->r); MP_DROP(f->f.q);
46 static mp *frand(field *f, mp *d, grand *r) {
47 return (mprand(d, f->nbits, r, 0));
50 static int fzerop(field *ff, mp *x) { return (MP_ZEROP(x)); }
52 static mp *fadd(field *ff, mp *d, mp *x, mp *y) { return (gf_add(d, x, y)); }
54 static mp *fmul(field *ff, mp *d, mp *x, mp *y) {
55 fctx_binpoly *f = (fctx_binpoly *)ff; d = gf_mul(d, x, y);
56 return (gfreduce_do(&f->r, d, d));
59 static mp *fsqr(field *ff, mp *d, mp *x) {
60 fctx_binpoly *f = (fctx_binpoly *)ff; d = gf_sqr(d, x);
61 return (gfreduce_do(&f->r, d, d));
64 static mp *finv(field *ff, mp *d, mp *x) {
65 fctx_binpoly *f = (fctx_binpoly *)ff;
66 d = gf_modinv(d, x, f->r.p);
70 static mp *freduce(field *ff, mp *d, mp *x) {
71 fctx_binpoly *f = (fctx_binpoly *)ff;
72 return (gfreduce_do(&f->r, d, x));
75 static mp *fsqrt(field *ff, mp *d, mp *x) {
76 fctx_binpoly *f = (fctx_binpoly *)ff;
77 return (gfreduce_sqrt(&f->r, d, x));
80 static mp *fquadsolve(field *ff, mp *d, mp *x) {
81 fctx_binpoly *f = (fctx_binpoly *)ff;
82 return (gfreduce_quadsolve(&f->r, d, x));
85 /* --- Field operations table --- */
87 static const field_ops fops = {
88 FTY_BINARY, "binpoly",
89 fdestroy, frand, field_stdsamep,
91 fzerop, field_id, fadd, fadd, fmul, fsqr, finv, freduce, fsqrt,
96 /* --- @field_binpoly@ --- *
98 * Arguments: @mp *p@ = the reduction polynomial
100 * Returns: A pointer to the field.
102 * Use: Creates a field structure for a binary field mod @p@.
105 field *field_binpoly(mp *p)
107 fctx_binpoly *f = CREATE(fctx_binpoly);
111 f->f.nbits = mp_bits(p) - 1;
112 f->f.noctets = (f->f.nbits + 7) >> 3;
113 gfreduce_create(&f->r, p);
115 f->f.q = mp_lsl(MP_NEW, MP_ONE, f->f.nbits);
119 /*----- Normal basis ------------------------------------------------------*/
121 /* --- Field operations --- */
123 static void fndestroy(field *ff) {
124 fctx_binnorm *f = (fctx_binnorm *)ff; gfreduce_destroy(&f->f.r);
125 gfn_destroy(&f->ntop); gfn_destroy(&f->pton); MP_DROP(f->f.f.q);
129 static int fnsamep(field *ff, field *gg) {
130 fctx_binnorm *f = (fctx_binnorm *)ff, *g = (fctx_binnorm *)gg;
131 return (MP_EQ(f->ntop.r[0], g->ntop.r[0]) && field_stdsamep(ff, gg));
134 static mp *fnin(field *ff, mp *d, mp *x) {
135 fctx_binnorm *f = (fctx_binnorm *)ff;
136 return (gfn_transform(&f->ntop, d, x));
139 static mp *fnout(field *ff, mp *d, mp *x) {
140 fctx_binnorm *f = (fctx_binnorm *)ff;
141 return (gfn_transform(&f->pton, d, x));
144 /* --- Field operations table --- */
146 static const field_ops fnops = {
147 FTY_BINARY, "binnorm",
148 fndestroy, frand, fnsamep,
150 fzerop, field_id, fadd, fadd, fmul, fsqr, finv, freduce, fsqrt,
155 /* --- @field_binnorm@ --- *
157 * Arguments: @mp *p@ = the reduction polynomial
158 * @mp *beta@ = representation of normal point
160 * Returns: A pointer to the field.
162 * Use: Creates a field structure for a binary field mod @p@ which
163 * uses a normal basis representation externally. Computations
164 * are still done on a polynomial-basis representation.
167 field *field_binnorm(mp *p, mp *beta)
169 fctx_binnorm *f = CREATE(fctx_binnorm);
171 f->f.f.zero = MP_ZERO;
173 f->f.f.nbits = mp_bits(p) - 1;
174 f->f.f.noctets = (f->f.f.nbits + 7) >> 3;
175 gfreduce_create(&f->f.r, p);
177 f->f.f.q = mp_lsl(MP_NEW, MP_ONE, f->f.f.nbits);
178 gfn_create(p, beta, &f->ntop, &f->pton);
182 /*----- That's all, folks -------------------------------------------------*/