/* -*-c-*-
*
- * $Id: g-prime.c,v 1.1 2004/04/01 12:50:09 mdw Exp $
+ * $Id$
*
* Abstraction for prime groups
*
* (c) 2004 Straylight/Edgeware
*/
-/*----- Licensing notice --------------------------------------------------*
+/*----- Licensing notice --------------------------------------------------*
*
* This file is part of Catacomb.
*
* 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.
*/
-/*----- Revision history --------------------------------------------------*
- *
- * $Log: g-prime.c,v $
- * Revision 1.1 2004/04/01 12:50:09 mdw
- * Add cyclic group abstraction, with test code. Separate off exponentation
- * functions for better static linking. Fix a buttload of bugs on the way.
- * Generally ensure that negative exponents do inversion correctly. Add
- * table of standard prime-field subgroups. (Binary field subgroups are
- * currently unimplemented but easy to add if anyone ever finds a good one.)
- *
- */
-
/*----- Header files ------------------------------------------------------*/
#include <mLib/sub.h>
#define ge mp *
#include "group.h"
-
-/*----- Data structures ---------------------------------------------------*/
-
-typedef struct gctx {
- group g;
- mp *gen;
- mpmont mm;
-} gctx;
+#include "group-guts.h"
/*----- Main code ---------------------------------------------------------*/
/* --- Group operations --- */
static void gdestroygroup(group *gg) {
- gctx *g = (gctx *)gg;
+ gctx_prime *g = (gctx_prime *)gg;
mp_drop(g->gen); mp_drop(g->g.r); mp_drop(g->g.h);
mpmont_destroy(&g->mm);
DESTROY(g);
static void gdestroy(group *gg, mp **x) { MP_DROP(*x); DESTROY(x); }
-static int gsamep(group *gg, group *hh)
- { gctx *g = (gctx *)gg, *h = (gctx *)hh; return (g->mm.m == h->mm.m); }
+static int gsamep(group *gg, group *hh) {
+ gctx_prime *g = (gctx_prime *)gg, *h = (gctx_prime *)hh;
+ return (MP_EQ(g->mm.m, h->mm.m));
+}
static int geq(group *gg, mp **x, mp **y) { return (MP_EQ(*x, *y)); }
static const char *gcheck(group *gg, grand *gr) {
- gctx *g = (gctx *)gg; int rc; mp *t;
+ gctx_prime *g = (gctx_prime *)gg; int rc; mp *t;
if (!pgen_primep(g->mm.m, gr)) return ("p is not prime");
t = mp_mul(MP_NEW, g->g.r, g->g.h); t = mp_add(t, t, MP_ONE);
rc = MP_EQ(t, g->mm.m); MP_DROP(t); if (!rc) return ("not a subgroup");
}
static void gmul(group *gg, mp **d, mp **x, mp **y)
- { gctx *g = (gctx *)gg; *d = mpmont_mul(&g->mm, *d, *x, *y); }
+ { gctx_prime *g = (gctx_prime *)gg; *d = mpmont_mul(&g->mm, *d, *x, *y); }
static void gsqr(group *gg, mp **d, mp **x) {
- gctx *g = (gctx *)gg; mp *r = mp_sqr(*d, *x);
+ gctx_prime *g = (gctx_prime *)gg; mp *r = mp_sqr(*d, *x);
*d = mpmont_reduce(&g->mm, r, r);
}
static void ginv(group *gg, mp **d, mp **x) {
- gctx *g = (gctx *)gg; mp *r = mpmont_reduce(&g->mm, *d, *x);
- mp_gcd(0, 0, &r, g->mm.m, r); *d = mpmont_mul(&g->mm, r, r, g->mm.r2);
+ gctx_prime *g = (gctx_prime *)gg; mp *r = mpmont_reduce(&g->mm, *d, *x);
+ r = mp_modinv(r, r, g->mm.m); *d = mpmont_mul(&g->mm, r, r, g->mm.r2);
}
static void gexp(group *gg, mp **d, mp **x, mp *n)
- { gctx *g = (gctx *)gg; *d = mpmont_expr(&g->mm, *d, *x, n); }
+ { gctx_prime *g = (gctx_prime *)gg; *d = mpmont_expr(&g->mm, *d, *x, n); }
static void gmexp(group *gg, mp **d, const group_expfactor *f, size_t n) {
- gctx *g = (gctx *)gg; size_t i;
+ gctx_prime *g = (gctx_prime *)gg; size_t i;
mp_expfactor *ff = xmalloc(n * sizeof(mp_expfactor));
for (i = 0; i < n; i++) { ff[i].base = *f[i].base; ff[i].exp = f[i].exp; }
*d = mpmont_mexpr(&g->mm, *d, ff, n); xfree(ff);
}
static int gread(group *gg, mp **d, const mptext_ops *ops, void *p) {
- gctx *g = (gctx *)gg; mp *t;
+ gctx_prime *g = (gctx_prime *)gg; mp *t;
if ((t = mp_read(MP_NEW, 0, ops, p)) == 0) return (-1);
mp_drop(*d); *d = mpmont_mul(&g->mm, t, t, g->mm.r2); return (0);
}
static int gwrite(group *gg, mp **x, const mptext_ops *ops, void *p) {
- gctx *g = (gctx *)gg; mp *t = mpmont_reduce(&g->mm, MP_NEW, *x);
+ gctx_prime *g = (gctx_prime *)gg;
+ mp *t = mpmont_reduce(&g->mm, MP_NEW, *x);
int rc = mp_write(t, 10, ops, p); MP_DROP(t); return (rc);
}
-static mp *gtoint(group *gg, mp *d, mp **x)
- { gctx *g = (gctx *)gg; return (mpmont_reduce(&g->mm, d, *x)); }
+static mp *gtoint(group *gg, mp *d, mp **x) {
+ gctx_prime *g = (gctx_prime *)gg;
+ return (mpmont_reduce(&g->mm, d, *x));
+}
static int gfromint(group *gg, mp **d, mp *x) {
- gctx *g = (gctx *)gg; mp_div(0, &x, x, g->mm.m); mp_drop(*d);
- *d = mpmont_mul(&g->mm, x, x, g->mm.r2); return (0);
+ gctx_prime *g = (gctx_prime *)gg; mp_div(0, d, x, g->mm.m);
+ *d = mpmont_mul(&g->mm, *d, *d, g->mm.r2); return (0);
}
static int gtobuf(group *gg, buf *b, mp **x) {
- gctx *g = (gctx *)gg; mp *t = mpmont_reduce(&g->mm, MP_NEW, *x);
+ gctx_prime *g = (gctx_prime *)gg;
+ mp *t = mpmont_reduce(&g->mm, MP_NEW, *x);
int rc = buf_putmp(b, t); MP_DROP(t); return (rc);
}
static int gfrombuf(group *gg, buf *b, mp **d) {
- gctx * g = (gctx *)gg; mp *x; if ((x = buf_getmp(b)) == 0) return (-1);
- mp_div(0, &x, x, g->mm.r2); mp_drop(*d);
+ gctx_prime * g = (gctx_prime *)gg; mp *x;
+ if ((x = buf_getmp(b)) == 0) return (-1);
+ mp_div(0, &x, x, g->mm.m); mp_drop(*d);
+ *d = mpmont_mul(&g->mm, x, x, g->mm.r2); return(0);
+}
+
+static int gtoraw(group *gg, buf *b, mp **x) {
+ gctx_prime *g = (gctx_prime *)gg; octet *q;
+ mp *t = mpmont_reduce(&g->mm, MP_NEW, *x);
+ if ((q = buf_get(b, g->g.noctets)) == 0) { MP_DROP(t); return (-1); }
+ mp_storeb(t, q, g->g.noctets); MP_DROP(t); return (0);
+}
+
+static int gfromraw(group *gg, buf *b, mp **d) {
+ gctx_prime * g = (gctx_prime *)gg; mp *x; octet *q;
+ if ((q = buf_get(b, g->g.noctets)) == 0) return (-1);
+ x = mp_loadb(MP_NEW, q, g->g.noctets);
+ mp_div(0, &x, x, g->mm.m); mp_drop(*d);
*d = mpmont_mul(&g->mm, x, x, g->mm.r2); return(0);
}
*
* Arguments: @const gprime_param *gp@ = group parameters
*
- * Returns: A pointer to the group.
+ * Returns: A pointer to the group, or null.
*
* Use: Constructs an abstract group interface for a subgroup of a
* prime field. Group elements are @mp *@ pointers.
*/
static const group_ops gops = {
- GTY_PRIME,
+ GTY_PRIME, "prime",
gdestroygroup, gcreate, gcopy, gburn, gdestroy,
gsamep, geq, group_stdidentp,
gcheck,
gmul, gsqr, ginv, group_stddiv, gexp, gmexp,
gread, gwrite,
- gtoint, gfromint, group_stdtoec, group_stdfromec, gtobuf, gfrombuf
+ gtoint, gfromint, group_stdtoec, group_stdfromec, gtobuf, gfrombuf,
+ gtoraw, gfromraw
};
group *group_prime(const gprime_param *gp)
{
- gctx *g = CREATE(gctx);
+ gctx_prime *g;
+ if (!MP_POSP(gp->p) || !MP_ODDP(gp->p))
+ return (0);
+ g = CREATE(gctx_prime);
g->g.ops = &gops;
g->g.nbits = mp_bits(gp->p);
g->g.noctets = (g->g.nbits + 7) >> 3;