3 * Abstraction for elliptic curve groups
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 ------------------------------------------------------*/
36 #include "group-guts.h"
38 /*----- Main code ---------------------------------------------------------*/
40 /* --- Group operations --- */
42 static void gdestroygroup(group *gg) {
43 gctx_ec *g = (gctx_ec *)gg;
49 static ec *gcreate(group *gg)
50 { ec *x = CREATE(ec); EC_CREATE(x); return (x); }
52 static void gcopy(group *gg, ec *d, ec *x) { EC_COPY(d, x); }
54 static void gburn(group *gg, ec *x) { if (x->x) (x->x)->f |= MP_BURN; }
56 static void gdestroy(group *gg, ec *x) { EC_DESTROY(x); DESTROY(x); }
58 static int gsamep(group *gg, group *hh) {
59 gctx_ec *g = (gctx_ec *)gg, *h = (gctx_ec *)hh;
60 return (ec_sameinfop(&g->ei, &h->ei));
63 static int geq(group *gg, ec *x, ec *y) {
64 gctx_ec *g = (gctx_ec *)gg; EC_FIX(g->ei.c, x, x); EC_FIX(g->ei.c, y, y);
68 static int gidentp(group *gg, ec *x) { return (EC_ATINF(x)); }
70 static const char *gcheck(group *gg, grand *gr)
71 { gctx_ec *g = (gctx_ec *)gg; return (ec_checkinfo(&g->ei, gr)); }
73 static void gmul(group *gg, ec *d, ec *x, ec *y)
74 { gctx_ec *g = (gctx_ec *)gg; EC_ADD(g->ei.c, d, x, y); }
76 static void gsqr(group *gg, ec *d, ec *x)
77 { gctx_ec *g = (gctx_ec *)gg; EC_DBL(g->ei.c, d, x); }
79 static void ginv(group *gg, ec *d, ec *x)
80 { gctx_ec *g = (gctx_ec *)gg; EC_NEG(g->ei.c, d, x); }
82 static void gdiv(group *gg, ec *d, ec *x, ec *y)
83 { gctx_ec *g = (gctx_ec *)gg; EC_SUB(g->ei.c, d, x, y); }
85 static void gexp(group *gg, ec *d, ec *x, mp *n)
86 { gctx_ec *g = (gctx_ec *)gg; ec_imul(g->ei.c, d, x, n); }
88 static void gmexp(group *gg, ec *d, const group_expfactor *f, size_t n) {
89 gctx_ec *g = (gctx_ec *)gg; size_t i;
90 ec_mulfactor *ff = xmalloc(n * sizeof(ec_mulfactor));
91 for (i = 0; i < n; i++) { ff[i].base = *f[i].base; ff[i].exp = f[i].exp; }
92 ec_immul(g->ei.c, d, ff, n); xfree(ff);
95 static int gread(group *gg, ec *d, const mptext_ops *ops, void *p) {
96 gctx_ec *g = (gctx_ec *)gg;
102 if (tolower(ch) == 'i') {
103 if (tolower(ops->get(p)) != 'n' || tolower(ops->get(p)) != 'f')
109 if ((t.x = mp_read(MP_NEW, 0, ops, p)) == 0) goto done;
110 do ch = ops->get(p); while (ch == ',' || isspace(ch)); ops->unget(ch, p);
111 if ((t.y = mp_read(MP_NEW, 0, ops, p)) == 0) goto done;
112 EC_IN(g->ei.c, &t, &t);
113 if (EC_CHECK(g->ei.c, &t)) goto done;
114 EC_COPY(d, &t); rc = 0;
120 static int gwrite(group *gg, ec *x, const mptext_ops *ops, void *p) {
121 gctx_ec *g = (gctx_ec *)gg; int rc = -1; ec t = EC_INIT;
122 EC_OUT(g->ei.c, &t, x); if (EC_ATINF(&t)) rc = ops->put("inf", 3, p);
123 else if (!ops->put("0x", 2, p) && !mp_write(t.x, 16, ops, p) &&
124 !ops->put(", 0x", 4, p) && !mp_write(t.y, 16, ops, p)) rc = 0;
125 EC_DESTROY(&t); return (rc);
128 static mp *gtoint(group *gg, mp *d, ec *x) {
129 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; mp *i; if (EC_ATINF(x)) i = 0;
130 else { EC_OUT(g->ei.c, &t, x); i = MP_COPY(t.x); EC_DESTROY(&t); }
131 mp_drop(d); return (i);
134 static int gfromint(group *gg, ec *d, mp *x) {
135 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT;
136 if (!ec_find(g->ei.c, &t, x)) return (-1);
137 EC_IN(g->ei.c, d, &t); EC_DESTROY(&t); return (0);
140 static int gtoec(group *gg, ec *d, ec *x)
141 { gctx_ec *g = (gctx_ec *)gg; EC_OUT(g->ei.c, d, x); return (0); }
143 static int gfromec(group *gg, ec *d, const ec *x) {
144 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc; EC_IN(g->ei.c, &t, x);
145 rc = EC_CHECK(g->ei.c, &t); if (!rc) EC_COPY(d, &t); EC_DESTROY(&t);
149 static int gtobuf(group *gg, buf *b, ec *x) {
150 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc;
151 EC_OUT(g->ei.c, &t, x); rc = buf_putec(b, &t); EC_DESTROY(&t); return (rc);
154 static int gfrombuf(group *gg, buf *b, ec *d) {
155 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc;
156 if (buf_getec(b, &t)) return (-1);
157 EC_IN(g->ei.c, &t, &t); rc = EC_CHECK(g->ei.c, &t);
158 if (!rc) EC_COPY(d, &t); EC_DESTROY(&t); return (rc);
161 static int gtoraw(group *gg, buf *b, ec *x) {
162 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc;
163 EC_OUT(g->ei.c, &t, x); rc = ec_putraw(g->ei.c, b, &t);
164 EC_DESTROY(&t); return (rc);
167 static int gfromraw(group *gg, buf *b, ec *d) {
168 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc;
169 if (ec_getraw(g->ei.c, b, &t)) return (-1);
170 EC_IN(g->ei.c, &t, &t); rc = EC_CHECK(g->ei.c, &t);
171 if (!rc) EC_COPY(d, &t); EC_DESTROY(&t); return (rc);
174 /* --- @group_ec@ --- *
176 * Arguments: @const ec_info *ei@ = elliptic curve parameters
178 * Returns: A pointer to the group.
180 * Use: Constructs an abstract group interface for an elliptic curve
181 * group. Group elements are @ec@ structures. The contents of
182 * the @ec_info@ structure becomes the property of the @group@
183 * object; you can (and should) free the structure itself, but
184 * calling @ec_freeinfo@ on it is not allowed.
187 static const group_ops gops = {
189 gdestroygroup, gcreate, gcopy, gburn, gdestroy,
190 gsamep, geq, gidentp,
192 gmul, gsqr, ginv, gdiv, gexp, gmexp,
194 gtoint, gfromint, gtoec, gfromec, gtobuf, gfrombuf, gtoraw, gfromraw
197 group *group_ec(const ec_info *ei)
199 gctx_ec *g = CREATE(gctx_ec);
202 g->g.nbits = ei->c->f->nbits * 2;
203 g->g.noctets = ei->c->f->noctets * 2 + 1;
209 EC_IN(g->ei.c, &g->gen, &ei->g);
215 /*----- That's all, folks -------------------------------------------------*/