X-Git-Url: https://git.distorted.org.uk/u/mdw/catacomb/blobdiff_plain/ba6e6b64033b1f9de49feccb5c9cd438354481f7..0f00dc4c8eb47e67bc0f148c2dd109f73a451e0a:/ec.c diff --git a/ec.c b/ec.c deleted file mode 100644 index cad7a56..0000000 --- a/ec.c +++ /dev/null @@ -1,424 +0,0 @@ -/* -*-c-*- - * - * $Id$ - * - * Elliptic curve definitions - * - * (c) 2001 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 "ec.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 - * - * Returns: The argument @p@. - * - * Use: Initializes a new point. The initial value is the additive - * identity (which is universal for all curves). - */ - -ec *ec_create(ec *p) { EC_CREATE(p); return (p); } - -/* --- @ec_destroy@ --- * - * - * Arguments: @ec *p@ = pointer to an elliptic-curve point - * - * Returns: --- - * - * Use: Destroys a point, making it invalid. - */ - -void ec_destroy(ec *p) { EC_DESTROY(p); } - -/* --- @ec_atinf@ --- * - * - * Arguments: @const ec *p@ = pointer to a point - * - * Returns: Nonzero if %$p = O$% is the point at infinity, zero - * otherwise. - */ - -int ec_atinf(const ec *p) { return (EC_ATINF(p)); } - -/* --- @ec_setinf@ --- * - * - * Arguments: @ec *p@ = pointer to a point - * - * Returns: The argument @p@. - * - * Use: Sets the given point to be the point %$O$% at infinity. - */ - -ec *ec_setinf(ec *p) { EC_SETINF(p); return (p); } - -/* --- @ec_copy@ --- * - * - * Arguments: @ec *d@ = pointer to destination point - * @const ec *p@ = pointer to source point - * - * Returns: The destination @d@. - * - * Use: Creates a copy of an elliptic curve point. - */ - -ec *ec_copy(ec *d, const ec *p) { EC_COPY(d, p); return (d); } - -/* --- @ec_eq@ --- * - * - * Arguments: @const ec *p, *q@ = two points - * - * Returns: Nonzero if the points are equal. Compares external-format - * points. - */ - -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 - * @ec *d@ = pointer to the destination - * @const ec *p@ = pointer to a source point - * - * Returns: The destination @d@. - * - * Use: An identity operation if your curve has no internal - * representation. (The field internal representation is still - * used.) - */ - -ec *ec_idin(ec_curve *c, ec *d, const ec *p) -{ - if (EC_ATINF(p)) - EC_SETINF(d); - else { - field *f = c->f; - d->x = F_IN(f, d->x, p->x); - d->y = F_IN(f, d->y, p->y); - mp_drop(d->z); d->z = 0; - } - return (d); -} - -ec *ec_idout(ec_curve *c, ec *d, const ec *p) -{ - if (EC_ATINF(p)) - EC_SETINF(d); - else { - field *f = c->f; - d->x = F_OUT(f, d->x, p->x); - d->y = F_OUT(f, d->y, p->y); - mp_drop(d->z); d->z = 0; - } - return (d); -} - -ec *ec_idfix(ec_curve *c, ec *d, const ec *p) - { EC_COPY(d, p); return (d); } - -/* --- @ec_projin@, @ec_projout@, @ec_projfix@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination - * @const ec *p@ = pointer to a source point - * - * Returns: The destination @d@. - * - * Use: Conversion functions if your curve operations use a - * projective representation. - */ - -ec *ec_projin(ec_curve *c, ec *d, const ec *p) -{ - if (EC_ATINF(p)) - EC_SETINF(d); - else { - field *f = c->f; - d->x = F_IN(f, d->x, p->x); - d->y = F_IN(f, d->y, p->y); - mp_drop(d->z); d->z = MP_COPY(f->one); - } - return (d); -} - -ec *ec_projout(ec_curve *c, ec *d, const ec *p) -{ - if (EC_ATINF(p)) - EC_SETINF(d); - else { - mp *x, *y, *z, *zz; - field *f = c->f; - 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->z = 0; - } - return (d); -} - -ec *ec_projfix(ec_curve *c, ec *d, const ec *p) -{ - if (EC_ATINF(p)) - EC_SETINF(d); - else if (p->z == c->f->one) - EC_COPY(d, p); - else { - mp *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); - d->x = F_MUL(f, d->x, p->x, zz); - d->y = F_MUL(f, d->y, p->y, z); - mp_drop(z); - mp_drop(zz); - mp_drop(d->z); - d->z = MP_COPY(f->one); - } - return (d); -} - -/* --- @ec_stdsub@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination - * @const ec *p, *q@ = the operand points - * - * Returns: The destination @d@. - * - * Use: Standard point subtraction operation, in terms of negation - * and addition. This isn't as efficient as a ready-made - * subtraction operator. - */ - -ec *ec_stdsub(ec_curve *c, ec *d, const ec *p, const ec *q) -{ - ec t = EC_INIT; - EC_NEG(c, &t, q); - EC_FIX(c, &t, &t); - EC_ADD(c, d, p, &t); - EC_DESTROY(&t); - return (d); -} - -/*----- Creating curves ---------------------------------------------------*/ - -/* --- @ec_destroycurve@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an ellptic curve - * - * Returns: --- - * - * Use: Destroys a description of an elliptic curve. - */ - -void ec_destroycurve(ec_curve *c) { c->ops->destroy(c); } - -/*----- Real arithmetic ---------------------------------------------------*/ - -/* --- @ec_find@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination point - * @mp *x@ = a possible x-coordinate - * - * Returns: Zero if OK, nonzero if there isn't a point there. - * - * Use: Finds a point on an elliptic curve with a given x-coordinate. - */ - -ec *ec_find(ec_curve *c, ec *d, mp *x) -{ - x = F_IN(c->f, MP_NEW, x); - if ((d = EC_FIND(c, d, x)) != 0) - EC_OUT(c, d, d); - MP_DROP(x); - return (d); -} - -/* --- @ec_neg@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination point - * @const ec *p@ = pointer to the operand point - * - * Returns: The destination point. - * - * Use: Computes the negation of the given point. - */ - -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_add@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination point - * @const ec *p, *q@ = pointers to the operand points - * - * Returns: --- - * - * Use: Adds two points on an elliptic curve. - */ - -ec *ec_add(ec_curve *c, ec *d, const ec *p, const ec *q) -{ - ec pp = EC_INIT, qq = EC_INIT; - EC_IN(c, &pp, p); - EC_IN(c, &qq, q); - EC_ADD(c, d, &pp, &qq); - EC_OUT(c, d, d); - EC_DESTROY(&pp); - EC_DESTROY(&qq); - return (d); -} - -/* --- @ec_sub@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination point - * @const ec *p, *q@ = pointers to the operand points - * - * Returns: The destination @d@. - * - * Use: Subtracts one point from another on an elliptic curve. - */ - -ec *ec_sub(ec_curve *c, ec *d, const ec *p, const ec *q) -{ - ec pp = EC_INIT, qq = EC_INIT; - EC_IN(c, &pp, p); - EC_IN(c, &qq, q); - EC_SUB(c, d, &pp, &qq); - EC_OUT(c, d, d); - EC_DESTROY(&pp); - EC_DESTROY(&qq); - return (d); -} - -/* --- @ec_dbl@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination point - * @const ec *p@ = pointer to the operand point - * - * Returns: --- - * - * Use: Doubles a point on an elliptic curve. - */ - -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_check@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @const ec *p@ = pointer to the point - * - * Returns: Zero if OK, nonzero if this is an invalid point. - * - * Use: Checks that a point is actually on an elliptic curve. - */ - -int ec_check(ec_curve *c, const ec *p) -{ - ec t = EC_INIT; - int rc; - - if (EC_ATINF(p)) - return (0); - EC_IN(c, &t, p); - rc = EC_CHECK(c, &t); - EC_DESTROY(&t); - return (rc); -} - -/* --- @ec_rand@ --- * - * - * Arguments: @ec_curve *c@ = pointer to an elliptic curve - * @ec *d@ = pointer to the destination point - * @grand *r@ = random number source - * - * Returns: The destination @d@. - * - * Use: Finds a random point on the given curve. - */ - -ec *ec_rand(ec_curve *c, ec *d, grand *r) -{ - mp *x = MP_NEW; - 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)); -} - -/*----- That's all, folks -------------------------------------------------*/