+++ /dev/null
-/* -*-c-*-
- *
- * $Id$
- *
- * Standard group operations
- *
- * (c) 2004 Straylight/Edgeware
- */
-
-/*----- Licensing notice --------------------------------------------------*
- *
- * This file is part of Catacomb.
- *
- * Catacomb is free software; you can redistribute it and/or modify
- * 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.
- */
-
-/*----- Header files ------------------------------------------------------*/
-
-#include "group.h"
-#include "pgen.h"
-
-/*----- Handy functions ---------------------------------------------------*/
-
-/* --- @group_check@ --- *
- *
- * Arguments: @group *g@ = an abstract group
- * @ge *x@ = a group element
- *
- * Returns: Zero on success, nonzero for failure.
- *
- * Use: Checks that @x@ is a valid group element. This may take a
- * while, since it checks that %$x \ne 1$% and %$x^r = 1$%.
- */
-
-int group_check(group *g, ge *x)
-{
- ge *d = G_CREATE(g);
- int rc;
-
- G_EXP(g, d, x, g->r);
- rc = (G_IDENTP(g, d) && !G_IDENTP(g, x));
- G_DESTROY(g, d);
- if (!rc) return (-1);
- return (0);
-}
-
-/* --- @group_samep@ --- *
- *
- * Arguments: @group *g, *h@ = two abstract groups
- *
- * Returns: Nonzero if the groups are in fact identical (not just
- * isomorphic).
- *
- * Use: Checks to see whether two groups are actually the same. This
- * function does the full check: the group operatrion @samep@
- * just does the group-specific details.
- */
-
-int group_samep(group *g, group *h)
-{
- return (g == h || (g->ops == h->ops &&
- MP_EQ(g->r, h->r) && MP_EQ(g->h, h->h) &&
- G_EQ(g, g->i, h->i) && G_EQ(g, g->g, h->g) &&
- G_SAMEP(g, h)));
-}
-
-/*----- Standard implementations ------------------------------------------*/
-
-/* --- @group_stdidentp@ --- *
- *
- * Arguments: @group *g@ = abstract group
- * @ge *x@ = group element
- *
- * Returns: Nonzero if %$x$% is the group identity.
- */
-
-int group_stdidentp(group *g, ge *x) { return (G_EQ(g, x, g->i)); }
-
-/* --- @group_stdsqr@ --- *
- *
- * Arguments: @group *g@ = abstract group
- * @ge *d@ = destination pointer
- * @ge *x@ = group element
- *
- * Returns: ---
- *
- * Use: Computes %$d = x^2$% as %$d = x x$%.
- */
-
-void group_stdsqr(group *g, ge *d, ge *x) { G_MUL(g, d, x, x); }
-
-/* --- @group_stddiv@ --- *
- *
- * Arguments: @group *g@ = abstract group
- * @ge *d@ = destination pointer
- * @ge *x@ = dividend
- * @ge *y@ = divisor
- *
- * Returns: ---
- *
- * Use: Computes %$d = x/y$% as %$d = x y^{-1}$%.
- */
-
-void group_stddiv(group *g, ge *d, ge *x, ge *y)
- { G_INV(g, d, y); G_MUL(g, d, x, d); }
-
-/* --- @group_stdtoec@ --- *
- *
- * Arguments: @group *g@ = abstract group
- * @ec *d@ = destination point
- * @ge *x@ = group element
- *
- * Returns: @-1@, indicating failure.
- *
- * Use: Fails to convert a group element to an elliptic curve point.
- */
-
-int group_stdtoec(group *g, ec *d, ge *x) { return (-1); }
-
-/* --- @group_stdfromec@ --- *
- *
- * Arguments: @group *g@ = abstract group
- * @ge *d@ = destination pointer
- * @const ec *p@ = elliptic curve point
- *
- * Returns: Zero for success, @-1@ on failure.
- *
- * Use: Converts %$p$% to a group element by converting its %$x$%-
- * coordinate.
- */
-
-int group_stdfromec(group *g, ge *d, const ec *p)
- { if (EC_ATINF(p)) return (-1); return (G_FROMINT(g, d, p->x)); }
-
-/* --- @group_stdcheck@ --- *
- *
- * Arguments: @group *g@ = abstract group
- * @grand *gr@ = random number source.
- *
- * Returns: Null on success, or a pointer to an error message.
- */
-
-const char *group_stdcheck(group *g, grand *gr)
-{
- ge *t;
- int rc;
-
- if (!pgen_primep(g->r, gr)) return ("group order not prime");
- t = G_CREATE(g); G_EXP(g, t, g->g, g->r);
- rc = G_IDENTP(g, t); G_DESTROY(g, t);
- if (!rc) return ("generator not in the group");
- return (0);
-}
-
-/*----- That's all, folks -------------------------------------------------*/