5 * Abstraction for elliptic curve groups
7 * (c) 2004 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
14 * Catacomb is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * Catacomb is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with Catacomb; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Header files ------------------------------------------------------*/
39 #include "group-guts.h"
41 /*----- Main code ---------------------------------------------------------*/
43 /* --- Group operations --- */
45 static void gdestroygroup(group *gg) {
46 gctx_ec *g = (gctx_ec *)gg;
52 static ec *gcreate(group *gg)
53 { ec *x = CREATE(ec); EC_CREATE(x); return (x); }
55 static void gcopy(group *gg, ec *d, ec *x) { EC_COPY(d, x); }
57 static void gburn(group *gg, ec *x) { if (x->x) (x->x)->f |= MP_BURN; }
59 static void gdestroy(group *gg, ec *x) { EC_DESTROY(x); DESTROY(x); }
61 static int gsamep(group *gg, group *hh) {
62 gctx_ec *g = (gctx_ec *)gg, *h = (gctx_ec *)hh;
63 return (ec_sameinfop(&g->ei, &h->ei));
66 static int geq(group *gg, ec *x, ec *y) {
67 gctx_ec *g = (gctx_ec *)gg; EC_FIX(g->ei.c, x, x); EC_FIX(g->ei.c, y, y);
71 static int gidentp(group *gg, ec *x) { return (EC_ATINF(x)); }
73 static const char *gcheck(group *gg, grand *gr)
74 { gctx_ec *g = (gctx_ec *)gg; return (ec_checkinfo(&g->ei, gr)); }
76 static void gmul(group *gg, ec *d, ec *x, ec *y)
77 { gctx_ec *g = (gctx_ec *)gg; EC_ADD(g->ei.c, d, x, y); }
79 static void gsqr(group *gg, ec *d, ec *x)
80 { gctx_ec *g = (gctx_ec *)gg; EC_DBL(g->ei.c, d, x); }
82 static void ginv(group *gg, ec *d, ec *x)
83 { gctx_ec *g = (gctx_ec *)gg; EC_NEG(g->ei.c, d, x); }
85 static void gdiv(group *gg, ec *d, ec *x, ec *y)
86 { gctx_ec *g = (gctx_ec *)gg; EC_SUB(g->ei.c, d, x, y); }
88 static void gexp(group *gg, ec *d, ec *x, mp *n)
89 { gctx_ec *g = (gctx_ec *)gg; ec_imul(g->ei.c, d, x, n); }
91 static void gmexp(group *gg, ec *d, const group_expfactor *f, size_t n) {
92 gctx_ec *g = (gctx_ec *)gg; size_t i;
93 ec_mulfactor *ff = xmalloc(n * sizeof(ec_mulfactor));
94 for (i = 0; i < n; i++) { ff[i].base = *f[i].base; ff[i].exp = f[i].exp; }
95 ec_immul(g->ei.c, d, ff, n); xfree(ff);
98 static int gread(group *gg, ec *d, const mptext_ops *ops, void *p) {
99 gctx_ec *g = (gctx_ec *)gg;
105 if (tolower(ch) == 'i') {
106 if (tolower(ops->get(p)) != 'n' || tolower(ops->get(p)) != 'f')
112 if ((t.x = mp_read(MP_NEW, 0, ops, p)) == 0) goto done;
113 do ch = ops->get(p); while (ch == ',' || isspace(ch)); ops->unget(ch, p);
114 if ((t.y = mp_read(MP_NEW, 0, ops, p)) == 0) goto done;
115 EC_IN(g->ei.c, &t, &t);
116 if (EC_CHECK(g->ei.c, &t)) goto done;
117 EC_COPY(d, &t); rc = 0;
123 static int gwrite(group *gg, ec *x, const mptext_ops *ops, void *p) {
124 gctx_ec *g = (gctx_ec *)gg; int rc = -1; ec t = EC_INIT;
125 EC_OUT(g->ei.c, &t, x); if (EC_ATINF(&t)) rc = ops->put("inf", 3, p);
126 else if (!ops->put("0x", 2, p) && !mp_write(t.x, 16, ops, p) &&
127 !ops->put(", 0x", 4, p) && !mp_write(t.y, 16, ops, p)) rc = 0;
128 EC_DESTROY(&t); return (rc);
131 static mp *gtoint(group *gg, mp *d, ec *x) {
132 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; mp *i; if (EC_ATINF(x)) i = 0;
133 else { EC_OUT(g->ei.c, &t, x); i = MP_COPY(t.x); EC_DESTROY(&t); }
134 mp_drop(d); return (i);
137 static int gfromint(group *gg, ec *d, mp *x) {
138 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT;
139 if (!ec_find(g->ei.c, &t, x)) return (-1);
140 EC_IN(g->ei.c, d, &t); EC_DESTROY(&t); return (0);
143 static int gtoec(group *gg, ec *d, ec *x)
144 { gctx_ec *g = (gctx_ec *)gg; EC_OUT(g->ei.c, d, x); return (0); }
146 static int gfromec(group *gg, ec *d, const ec *x) {
147 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc; EC_IN(g->ei.c, &t, x);
148 rc = EC_CHECK(g->ei.c, &t); if (!rc) EC_COPY(d, &t); EC_DESTROY(&t);
152 static int gtobuf(group *gg, buf *b, ec *x) {
153 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc;
154 EC_OUT(g->ei.c, &t, x); rc = buf_putec(b, &t); EC_DESTROY(&t); return (rc);
157 static int gfrombuf(group *gg, buf *b, ec *d) {
158 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc;
159 if (buf_getec(b, &t)) return (-1);
160 EC_IN(g->ei.c, &t, &t); rc = EC_CHECK(g->ei.c, &t);
161 if (!rc) EC_COPY(d, &t); EC_DESTROY(&t); return (rc);
164 static int gtoraw(group *gg, buf *b, ec *x) {
165 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc;
166 EC_OUT(g->ei.c, &t, x); rc = ec_putraw(g->ei.c, b, &t);
167 EC_DESTROY(&t); return (rc);
170 static int gfromraw(group *gg, buf *b, ec *d) {
171 gctx_ec *g = (gctx_ec *)gg; ec t = EC_INIT; int rc;
172 if (ec_getraw(g->ei.c, b, &t)) return (-1);
173 EC_IN(g->ei.c, &t, &t); rc = EC_CHECK(g->ei.c, &t);
174 if (!rc) EC_COPY(d, &t); EC_DESTROY(&t); return (rc);
177 /* --- @group_ec@ --- *
179 * Arguments: @const ec_info *ei@ = elliptic curve parameters
181 * Returns: A pointer to the group.
183 * Use: Constructs an abstract group interface for an elliptic curve
184 * group. Group elements are @ec@ structures. The contents of
185 * the @ec_info@ structure becomes the property of the @group@
186 * object; you can (and should) free the structure itself, but
187 * calling @ec_freeinfo@ on it is not allowed.
190 static const group_ops gops = {
192 gdestroygroup, gcreate, gcopy, gburn, gdestroy,
193 gsamep, geq, gidentp,
195 gmul, gsqr, ginv, gdiv, gexp, gmexp,
197 gtoint, gfromint, gtoec, gfromec, gtobuf, gfrombuf, gtoraw, gfromraw
200 group *group_ec(const ec_info *ei)
202 gctx_ec *g = CREATE(gctx_ec);
205 g->g.nbits = ei->c->f->nbits * 2;
206 g->g.noctets = ei->c->f->noctets * 2 + 1;
212 EC_IN(g->ei.c, &g->gen, &ei->g);
218 /*----- That's all, folks -------------------------------------------------*/