/* -*-c-*-
*
- * $Id: g-prime.c,v 1.1 2004/04/01 12:50:09 mdw Exp $
+ * $Id: g-prime.c,v 1.4 2004/04/08 01:36:15 mdw Exp $
*
* Abstraction for prime groups
*
* 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>
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 *g = (gctx *)gg, *h = (gctx *)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 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);
+ 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; 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 *g = (gctx *)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) {
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);
+ 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 *g = (gctx *)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 * g = (gctx *)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.
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 *g;
+ if (!MP_ISPOS(gp->p) || !MP_ISODD(gp->p))
+ return (0);
+ g = CREATE(gctx);
g->g.ops = &gops;
g->g.nbits = mp_bits(gp->p);
g->g.noctets = (g->g.nbits + 7) >> 3;