chiark / gitweb /
rand/rand.c (rand_gate): Evolve r->ibits in a more sensible manner.
[catacomb] / math / g-bin.c
CommitLineData
3688eb75 1/* -*-c-*-
3688eb75 2 *
3 * Abstraction for prime groups
4 *
5 * (c) 2004 Straylight/Edgeware
6 */
7
45c0fd36 8/*----- Licensing notice --------------------------------------------------*
3688eb75 9 *
10 * This file is part of Catacomb.
11 *
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.
45c0fd36 16 *
3688eb75 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.
45c0fd36 21 *
3688eb75 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,
25 * MA 02111-1307, USA.
26 */
27
28/*----- Header files ------------------------------------------------------*/
29
30#include <mLib/sub.h>
31
32#include "mpmont.h"
33#include "pgen.h"
34
b919de21 35#define ge ge_bin
3688eb75 36#include "group-guts.h"
37
38/*----- Main code ---------------------------------------------------------*/
39
40/* --- Group operations --- */
41
42static void gdestroygroup(group *gg) {
43 gctx_bin *g = (gctx_bin *)gg;
b919de21 44 mp_drop(g->gen.x); mp_drop(g->g.r); mp_drop(g->g.h);
3688eb75 45 gfreduce_destroy(&g->r);
46 DESTROY(g);
47}
48
b919de21
MW
49static ge_bin *gcreate(group *gg) {
50 gctx_bin *g = (gctx_bin *)gg; ge_bin *x = CREATE(ge_bin);
51 x->x = MP_COPY(g->one.x); return (x);
52}
3688eb75 53
b919de21
MW
54static void gcopy(group *gg, ge_bin *d, ge_bin *x)
55 { mp *t = MP_COPY(x->x); MP_DROP(d->x); d->x = t; }
3688eb75 56
b919de21 57static void gburn(group *gg, ge_bin *x) { x->x->f |= MP_BURN; }
3688eb75 58
b919de21 59static void gdestroy(group *gg, ge_bin *x) { MP_DROP(x->x); DESTROY(x); }
3688eb75 60
61static int gsamep(group *gg, group *hh) {
62 gctx_bin *g = (gctx_bin *)gg, *h = (gctx_bin *)hh;
63 return (MP_EQ(g->r.p, h->r.p));
64}
65
b919de21
MW
66static int geq(group *gg, ge_bin *x, ge_bin *y)
67 { return (MP_EQ(x->x, y->x)); }
3688eb75 68
69static const char *gcheck(group *gg, grand *gr) {
70 gctx_bin *g = (gctx_bin *)gg; int rc; mp *t, *tt;
71 if (!gf_irreduciblep(g->r.p)) return ("p is not irreducible");
72 t = mp_mul(MP_NEW, g->g.r, g->g.h); t = mp_add(t, t, MP_ONE);
73 tt = mp_lsl(MP_NEW, MP_ONE, g->g.nbits);
74 rc = MP_EQ(t, tt); MP_DROP(t); MP_DROP(tt);
75 if (!rc) return ("not a subgroup");
76 return (group_stdcheck(gg, gr));
77}
78
b919de21
MW
79static void gmul(group *gg, ge_bin *d, ge_bin *x, ge_bin *y) {
80 gctx_bin *g = (gctx_bin *)gg; mp *r = gf_mul(d->x, x->x, y->x);
81 d->x = gfreduce_do(&g->r, r, r);
3688eb75 82}
83
b919de21
MW
84static void gsqr(group *gg, ge_bin *d, ge_bin *x) {
85 gctx_bin *g = (gctx_bin *)gg; mp *r = gf_sqr(d->x, x->x);
86 d->x = gfreduce_do(&g->r, r, r);
3688eb75 87}
88
b919de21
MW
89static void ginv(group *gg, ge_bin *d, ge_bin *x)
90 { gctx_bin *g = (gctx_bin *)gg; d->x = gf_modinv(d->x, x->x, g->r.p); }
3688eb75 91
b919de21
MW
92static void gexp(group *gg, ge_bin *d, ge_bin *x, mp *n) {
93 gctx_bin *g = (gctx_bin *)gg;
94 d->x = gfreduce_exp(&g->r, d->x, x->x, n);
95}
3688eb75 96
b919de21 97static int gread(group *gg, ge_bin *d, const mptext_ops *ops, void *p) {
3688eb75 98 mp *t; if ((t = mp_read(MP_NEW, 0, ops, p)) == 0) return (-1);
b919de21 99 mp_drop(d->x); d->x = t; return (0);
3688eb75 100}
101
b919de21 102static int gwrite(group *gg, ge_bin *x, const mptext_ops *ops, void *p) {
3688eb75 103 int rc = -1;
b919de21 104 if (!ops->put("0x", 2, p) && !mp_write(x->x, 16, ops, p)) rc = 0;
3688eb75 105 return (rc);
106}
107
b919de21 108static mp *gtoint(group *gg, mp *d, ge_bin *x) { return MP_COPY(x->x); }
3688eb75 109
b919de21
MW
110static int gfromint(group *gg, ge_bin *d, mp *x)
111 { d->x = MP_COPY(x); return 0; }
3688eb75 112
b919de21
MW
113static int gtobuf(group *gg, buf *b, ge_bin *x)
114 { int rc = buf_putmp(b, x->x); return (rc); }
3688eb75 115
b919de21 116static int gfrombuf(group *gg, buf *b, ge_bin *d) {
3688eb75 117 gctx_bin *g = (gctx_bin *)gg; mp *x;
118 if ((x = buf_getmp(b)) == 0) return (-1);
b919de21 119 MP_DROP(d->x); d->x = gfreduce_do(&g->r, x, x);
3688eb75 120 return (0);
121}
122
b919de21
MW
123static int gtoraw(group *gg, buf *b, ge_bin *x) {
124 gctx_bin *g = (gctx_bin *)gg; octet *q;
3688eb75 125 if ((q = buf_get(b, g->g.noctets)) == 0) return (-1);
b919de21 126 mp_storeb(x->x, q, g->g.noctets); return (0);
3688eb75 127}
128
b919de21
MW
129static int gfromraw(group *gg, buf *b, ge_bin *d) {
130 gctx_bin *g = (gctx_bin *)gg; mp *x; octet *q;
3688eb75 131 if ((q = buf_get(b, g->g.noctets)) == 0) return (-1);
132 x = mp_loadb(MP_NEW, q, g->g.noctets);
b919de21 133 MP_DROP(d->x); d->x = gfreduce_do(&g->r, x, x);
3688eb75 134 return (0);
135}
136
137/* --- @group_binary@ --- *
138 *
139 * Arguments: @const gbin_param *gb@ = group parameters
140 *
141 * Returns: A pointer to the group, or null.
142 *
143 * Use: Constructs an abstract group interface for a subgroup of a
144 * prime field. Group elements are @mp *@ pointers.
145 */
146
147static const group_ops gops = {
148 GTY_BINARY, "bin",
149 gdestroygroup, gcreate, gcopy, gburn, gdestroy,
150 gsamep, geq, group_stdidentp,
151 gcheck,
152 gmul, gsqr, ginv, group_stddiv, gexp, group_stdmexp,
153 gread, gwrite,
154 gtoint, gfromint, group_stdtoec, group_stdfromec, gtobuf, gfrombuf,
155 gtoraw, gfromraw
156};
157
158group *group_binary(const gbin_param *gb)
159{
160 gctx_bin *g;
161 mp *t;
162
163 if (!MP_POSP(gb->p))
164 return (0);
165 g = CREATE(gctx_bin);
166 g->g.ops = &gops;
167 g->g.nbits = mp_bits(gb->p) - 1;
168 g->g.noctets = (g->g.nbits + 7) >> 3;
169 gfreduce_create(&g->r, gb->p);
b919de21 170 g->one.x = MP_ONE;
3688eb75 171 g->g.i = &g->one;
b919de21 172 g->gen.x = MP_COPY(gb->g);
3688eb75 173 g->g.g = &g->gen;
174 g->g.r = MP_COPY(gb->q);
175 t = mp_lsl(MP_NEW, MP_ONE, g->g.nbits);
176 t = mp_sub(t, t, MP_ONE);
177 g->g.h = MP_NEW; mp_div(&g->g.h, 0, t, gb->q);
178 MP_DROP(t);
179 return (&g->g);
180}
181
182/*----- That's all, folks -------------------------------------------------*/