X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/bc985cefafea2e1b02095a2ff2a9982c4c647d17..18b3351a3791f19a63c0af05640719db8eb5d184:/ec.c diff --git a/ec.c b/ec.c index ac00c92..cad7a56 100644 --- a/ec.c +++ b/ec.c @@ -1,13 +1,13 @@ /* -*-c-*- * - * $Id: ec.c,v 1.6 2004/03/23 15:19:32 mdw Exp $ + * $Id$ * * Elliptic curve definitions * * (c) 2001 Straylight/Edgeware */ -/*----- Licensing notice --------------------------------------------------* +/*----- Licensing notice --------------------------------------------------* * * This file is part of Catacomb. * @@ -15,55 +15,41 @@ * 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: ec.c,v $ - * Revision 1.6 2004/03/23 15:19:32 mdw - * Test elliptic curves more thoroughly. - * - * Revision 1.5 2004/03/21 22:52:06 mdw - * Merge and close elliptic curve branch. - * - * Revision 1.4.4.2 2004/03/20 00:13:31 mdw - * Projective coordinates for prime curves - * - * Revision 1.4.4.1 2003/06/10 13:43:53 mdw - * Simple (non-projective) curves over prime fields now seem to work. - * - * Revision 1.4 2003/05/15 23:25:59 mdw - * Make elliptic curve stuff build. - * - * Revision 1.3 2002/01/13 13:48:44 mdw - * Further progress. - * - * Revision 1.2 2001/05/07 17:29:44 mdw - * Treat projective coordinates as an internal representation. Various - * minor interface changes. - * - * Revision 1.1 2001/04/29 18:12:33 mdw - * Prototype version. - * - */ - /*----- Header files ------------------------------------------------------*/ #include "ec.h" -#include "ec-exp.h" /*----- Trivial wrappers --------------------------------------------------*/ +/* --- @ec_samep@ --- * + * + * Arguments: @ec_curve *c, *d@ = two elliptic curves + * + * Returns: Nonzero if the curves are identical (not just isomorphic). + * + * Use: Checks for sameness of curves. This function does the full + * check, not just the curve-type-specific check done by the + * @sampep@ field operation. + */ + +int ec_samep(ec_curve *c, ec_curve *d) +{ + return (c == d || (field_samep(c->f, d->f) && + c->ops == d->ops && EC_SAMEP(c, d))); +} + /* --- @ec_create@ --- * * * Arguments: @ec *p@ = pointer to an elliptic-curve point @@ -132,6 +118,18 @@ int ec_eq(const ec *p, const ec *q) { return (EC_EQ(p, q)); } /*----- Standard curve operations -----------------------------------------*/ +/* --- @ec_stdsamep@ --- * + * + * Arguments: @ec_curve *c, *d@ = two elliptic curves + * + * Returns: Nonzero if the curves are identical (not just isomorphic). + * + * Use: Simple sameness check on @a@ and @b@ curve members. + */ + +int ec_stdsamep(ec_curve *c, ec_curve *d) + { return (MP_EQ(c->a, d->a) && MP_EQ(c->b, d->b)); } + /* --- @ec_idin@, @ec_idout@, @ec_idfix@ --- * * * Arguments: @ec_curve *c@ = pointer to an elliptic curve @@ -172,12 +170,9 @@ ec *ec_idout(ec_curve *c, ec *d, const ec *p) } ec *ec_idfix(ec_curve *c, ec *d, const ec *p) -{ - EC_COPY(d, p); - return (d); -} + { EC_COPY(d, p); return (d); } -/* --- @ec_projin@, @ec_projout@ --- * +/* --- @ec_projin@, @ec_projout@, @ec_projfix@ --- * * * Arguments: @ec_curve *c@ = pointer to an elliptic curve * @ec *d@ = pointer to the destination @@ -209,16 +204,21 @@ ec *ec_projout(ec_curve *c, ec *d, const ec *p) else { mp *x, *y, *z, *zz; field *f = c->f; - z = F_INV(f, MP_NEW, p->z); - zz = F_SQR(f, MP_NEW, z); - z = F_MUL(f, z, zz, z); - x = F_MUL(f, d->x, p->x, zz); - y = F_MUL(f, d->y, p->y, z); - mp_drop(z); - mp_drop(zz); + if (p->z == f->one) { + d->x = F_OUT(f, d->x, p->x); + d->y = F_OUT(f, d->y, p->y); + } else { + z = F_INV(f, MP_NEW, p->z); + zz = F_SQR(f, MP_NEW, z); + z = F_MUL(f, z, zz, z); + x = F_MUL(f, d->x, p->x, zz); + y = F_MUL(f, d->y, p->y, z); + mp_drop(z); + mp_drop(zz); + d->x = F_OUT(f, x, x); + d->y = F_OUT(f, y, y); + } mp_drop(d->z); - d->x = F_OUT(f, x, x); - d->y = F_OUT(f, y, y); d->z = 0; } return (d); @@ -228,7 +228,7 @@ ec *ec_projfix(ec_curve *c, ec *d, const ec *p) { if (EC_ATINF(p)) EC_SETINF(d); - else if (d->z == c->f->one) + else if (p->z == c->f->one) EC_COPY(d, p); else { mp *z, *zz; @@ -243,7 +243,7 @@ ec *ec_projfix(ec_curve *c, ec *d, const ec *p) mp_drop(d->z); d->z = MP_COPY(f->one); } - return (d); + return (d); } /* --- @ec_stdsub@ --- * @@ -316,11 +316,7 @@ ec *ec_find(ec_curve *c, ec *d, mp *x) */ ec *ec_neg(ec_curve *c, ec *d, const ec *p) -{ - EC_IN(c, d, p); - EC_NEG(c, d, d); - return (EC_OUT(c, d, d)); -} + { EC_IN(c, d, p); EC_NEG(c, d, d); return (EC_OUT(c, d, d)); } /* --- @ec_add@ --- * * @@ -358,7 +354,7 @@ ec *ec_add(ec_curve *c, ec *d, const ec *p, const ec *q) ec *ec_sub(ec_curve *c, ec *d, const ec *p, const ec *q) { - ec pp, qq; + ec pp = EC_INIT, qq = EC_INIT; EC_IN(c, &pp, p); EC_IN(c, &qq, q); EC_SUB(c, d, &pp, &qq); @@ -380,11 +376,7 @@ ec *ec_sub(ec_curve *c, ec *d, const ec *p, const ec *q) */ ec *ec_dbl(ec_curve *c, ec *d, const ec *p) -{ - EC_IN(c, d, p); - EC_DBL(c, d, d); - return (EC_OUT(c, d, d)); -} + { EC_IN(c, d, p); EC_DBL(c, d, d); return (EC_OUT(c, d, d)); } /* --- @ec_check@ --- * * @@ -426,50 +418,6 @@ ec *ec_rand(ec_curve *c, ec *d, grand *r) do x = F_RAND(c->f, x, r); while (!EC_FIND(c, d, x)); mp_drop(x); if (grand_range(r, 2)) EC_NEG(c, d, d); - return (EC_OUT(c, d, d)); -} - -/* --- @ec_imul@, @ec_mul@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination point - * @const ec *p@ = pointer to the generator point - * @mp *n@ = integer multiplier - * - * Returns: The destination @d@. - * - * Use: Multiplies a point by a scalar, returning %$n p$%. The - * @imul@ variant uses internal representations for argument - * and result. - */ - -ec *ec_imul(ec_curve *c, ec *d, const ec *p, mp *n) -{ - ec t = EC_INIT; - - EC_COPY(&t, p); - if (t.x && (n->f & MP_BURN)) - t.x->f |= MP_BURN; - MP_SHRINK(n); - EC_SETINF(d); - if (MP_LEN(n) == 0) - ; - else { - if (n->f & MP_NEG) - EC_NEG(c, &t, &t); - if (MP_LEN(n) < EXP_THRESH) - EXP_SIMPLE(*d, t, n); - else - EXP_WINDOW(*d, t, n); - } - EC_DESTROY(&t); - return (d); -} - -ec *ec_mul(ec_curve *c, ec *d, const ec *p, mp *n) -{ - EC_IN(c, d, p); - ec_imul(c, d, d, n); return (EC_OUT(c, d, d)); }