crypto/ecc/ecp_aff.c

f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/*
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * ***** BEGIN LICENSE BLOCK *****
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Version: MPL 1.1/GPL 2.0/LGPL 2.1
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * The contents of this file are subject to the Mozilla Public License Version
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * 1.1 (the "License"); you may not use this file except in compliance with
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * the License. You may obtain a copy of the License at
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * http://www.mozilla.org/MPL/
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Software distributed under the License is distributed on an "AS IS" basis,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * for the specific language governing rights and limitations under the
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * License.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * The Original Code is the elliptic curve math library for prime field curves.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * The Initial Developer of the Original Code is
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Sun Microsystems, Inc.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Portions created by the Initial Developer are Copyright (C) 2003
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * the Initial Developer. All Rights Reserved.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Contributor(s):
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *   Sheueling Chang-Shantz <sheueling.chang@sun.com>,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *   Stephen Fung <fungstep@hotmail.com>, and
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *   Douglas Stebila <douglas@stebila.ca>, Sun Microsystems Laboratories.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *   Bodo Moeller <moeller@cdc.informatik.tu-darmstadt.de>,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *   Nils Larsch <nla@trustcenter.de>, and
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *   Lenka Fibikova <fibikova@exp-math.uni-essen.de>, the OpenSSL Project
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Alternatively, the contents of this file may be used under the terms of
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * either the GNU General Public License Version 2 or later (the "GPL"), or
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * in which case the provisions of the GPL or the LGPL are applicable instead
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * of those above. If you wish to allow use of your version of this file only
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * under the terms of either the GPL or the LGPL, and not to allow others to
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * use your version of this file under the terms of the MPL, indicate your
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * decision by deleting the provisions above and replace them with the notice
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * and other provisions required by the GPL or the LGPL. If you do not delete
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * the provisions above, a recipient may use your version of this file under
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * the terms of any one of the MPL, the GPL or the LGPL.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * ***** END LICENSE BLOCK ***** */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/*
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Use is subject to license terms.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers *
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Sun elects to use this software under the MPL license.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#pragma ident   "%Z%%M% %I% %E% SMI"
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#include "ecp.h"
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#include "mplogic.h"
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#ifndef _KERNEL
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#include <stdlib.h>
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#endif
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Checks if point P(px, py) is at infinity.  Uses affine coordinates. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_pt_is_inf_aff(const mp_int *px, const mp_int *py)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if ((mp_cmp_z(px) == 0) && (mp_cmp_z(py) == 0)) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        return MP_YES;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    } else {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        return MP_NO;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Sets P(px, py) to be the point at infinity.  Uses affine coordinates. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_pt_set_inf_aff(mp_int *px, mp_int *py)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_zero(px);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_zero(py);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Computes R = P + Q based on IEEE P1363 A.10.1. Elliptic curve points P,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Q, and R can all be identical. Uses affine coordinates. Assumes input
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * is already field-encoded using field_enc, and returns output that is
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * still field-encoded. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_pt_add_aff(const mp_int *px, const mp_int *py, const mp_int *qx,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                  const mp_int *qy, mp_int *rx, mp_int *ry,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                  const ECGroup *group)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_err res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_int lambda, temp, tempx, tempy;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&lambda) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&temp) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&tempx) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&tempy) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&lambda, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&temp, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&tempx, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&tempy, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* if P = inf, then R = Q */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (ec_GFp_pt_is_inf_aff(px, py) == 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_copy(qx, rx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_copy(qy, ry));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        goto CLEANUP;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* if Q = inf, then R = P */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (ec_GFp_pt_is_inf_aff(qx, qy) == 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_copy(px, rx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_copy(py, ry));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        goto CLEANUP;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* if px != qx, then lambda = (py-qy) / (px-qx) */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (mp_cmp(px, qx) != 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->field_sub(py, qy, &tempy, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->field_sub(px, qx, &tempx, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                   field_div(&tempy, &tempx, &lambda, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    } else {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* if py != qy or qy = 0, then R = inf */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (((mp_cmp(py, qy) != 0)) || (mp_cmp_z(qy) == 0)) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            mp_zero(rx);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            mp_zero(ry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            goto CLEANUP;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* lambda = (3qx^2+a) / (2qy) */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->field_sqr(qx, &tempx, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_set_int(&temp, 3));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (group->meth->field_enc) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_CHECKOK(group->meth->field_enc(&temp, &temp, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                   field_mul(&tempx, &temp, &tempx, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                   field_add(&tempx, &group->curvea, &tempx, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_set_int(&temp, 2));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (group->meth->field_enc) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_CHECKOK(group->meth->field_enc(&temp, &temp, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->field_mul(qy, &temp, &tempy, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                   field_div(&tempx, &tempy, &lambda, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* rx = lambda^2 - px - qx */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(group->meth->field_sqr(&lambda, &tempx, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(group->meth->field_sub(&tempx, px, &tempx, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(group->meth->field_sub(&tempx, qx, &tempx, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* ry = (x1-x2) * lambda - y1 */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(group->meth->field_sub(qx, &tempx, &tempy, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(group->meth->
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers               field_mul(&tempy, &lambda, &tempy, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(group->meth->field_sub(&tempy, qy, &tempy, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(&tempx, rx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(&tempy, ry));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers  CLEANUP:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&lambda);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&temp);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&tempx);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&tempy);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return res;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Computes R = P - Q. Elliptic curve points P, Q, and R can all be
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * identical. Uses affine coordinates. Assumes input is already
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * field-encoded using field_enc, and returns output that is still
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * field-encoded. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_pt_sub_aff(const mp_int *px, const mp_int *py, const mp_int *qx,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                  const mp_int *qy, mp_int *rx, mp_int *ry,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                  const ECGroup *group)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_err res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_int nqy;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&nqy) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&nqy, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* nqy = -qy */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(group->meth->field_neg(qy, &nqy, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    res = group->point_add(px, py, qx, &nqy, rx, ry, group);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers  CLEANUP:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&nqy);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return res;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Computes R = 2P. Elliptic curve points P and R can be identical. Uses
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * affine coordinates. Assumes input is already field-encoded using
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * field_enc, and returns output that is still field-encoded. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_pt_dbl_aff(const mp_int *px, const mp_int *py, mp_int *rx,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                  mp_int *ry, const ECGroup *group)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return ec_GFp_pt_add_aff(px, py, px, py, rx, ry, group);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* by default, this routine is unused and thus doesn't need to be compiled */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#ifdef ECL_ENABLE_GFP_PT_MUL_AFF
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Computes R = nP based on IEEE P1363 A.10.3. Elliptic curve points P and
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * R can be identical. Uses affine coordinates. Assumes input is already
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * field-encoded using field_enc, and returns output that is still
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * field-encoded. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_pt_mul_aff(const mp_int *n, const mp_int *px, const mp_int *py,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                  mp_int *rx, mp_int *ry, const ECGroup *group)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_err res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_int k, k3, qx, qy, sx, sy;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    int b1, b3, i, l;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&k) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&k3) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&qx) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&qy) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&sx) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&sy) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&k));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&k3));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&qx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&qy));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&sx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&sy));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* if n = 0 then r = inf */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (mp_cmp_z(n) == 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_zero(rx);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_zero(ry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        goto CLEANUP;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* Q = P, k = n */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(px, &qx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(py, &qy));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(n, &k));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* if n < 0 then Q = -Q, k = -k */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (mp_cmp_z(n) < 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->meth->field_neg(&qy, &qy, group->meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_neg(&k, &k));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#ifdef ECL_DEBUG                /* basic double and add method */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    l = mpl_significant_bits(&k) - 1;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(&qx, &sx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(&qy, &sy));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    for (i = l - 1; i >= 0; i--) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* S = 2S */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->point_dbl(&sx, &sy, &sx, &sy, group));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* if k_i = 1, then S = S + Q */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (mpl_get_bit(&k, i) != 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_CHECKOK(group->
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                       point_add(&sx, &sy, &qx, &qy, &sx, &sy, group));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#else                           /* double and add/subtract method from
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                                 * standard */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* k3 = 3 * k */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_set_int(&k3, 3));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_mul(&k, &k3, &k3));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* S = Q */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(&qx, &sx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(&qy, &sy));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* l = index of high order bit in binary representation of 3*k */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    l = mpl_significant_bits(&k3) - 1;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* for i = l-1 downto 1 */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    for (i = l - 1; i >= 1; i--) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* S = 2S */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(group->point_dbl(&sx, &sy, &sx, &sy, group));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        b3 = MP_GET_BIT(&k3, i);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        b1 = MP_GET_BIT(&k, i);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* if k3_i = 1 and k_i = 0, then S = S + Q */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if ((b3 == 1) && (b1 == 0)) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_CHECKOK(group->
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                       point_add(&sx, &sy, &qx, &qy, &sx, &sy, group));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            /* if k3_i = 0 and k_i = 1, then S = S - Q */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        } else if ((b3 == 0) && (b1 == 1)) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_CHECKOK(group->
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                       point_sub(&sx, &sy, &qx, &qy, &sx, &sy, group));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#endif
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* output S */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(&sx, rx));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_copy(&sy, ry));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers  CLEANUP:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&k);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&k3);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&qx);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&qy);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&sx);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&sy);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return res;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#endif
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Validates a point on a GFp curve. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_validate_point(const mp_int *px, const mp_int *py, const ECGroup *group)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_err res = MP_NO;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_int accl, accr, tmp, pxt, pyt;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&accl) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&accr) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&tmp) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&pxt) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_DIGITS(&pyt) = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&accl, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&accr, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&tmp, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&pxt, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_init(&pyt, FLAG(px)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* 1: Verify that publicValue is not the point at infinity */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (ec_GFp_pt_is_inf_aff(px, py) == MP_YES) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        res = MP_NO;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        goto CLEANUP;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* 2: Verify that the coordinates of publicValue are elements
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers     *    of the field.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers     */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if ((MP_SIGN(px) == MP_NEG) || (mp_cmp(px, &group->meth->irr) >= 0) ||
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        (MP_SIGN(py) == MP_NEG) || (mp_cmp(py, &group->meth->irr) >= 0)) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        res = MP_NO;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        goto CLEANUP;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* 3: Verify that publicValue is on the curve. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (group->meth->field_enc) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        group->meth->field_enc(px, &pxt, group->meth);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        group->meth->field_enc(py, &pyt, group->meth);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    } else {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_copy(px, &pxt);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_copy(py, &pyt);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* left-hand side: y^2  */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK( group->meth->field_sqr(&pyt, &accl, group->meth) );
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* right-hand side: x^3 + a*x + b */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK( group->meth->field_sqr(&pxt, &tmp, group->meth) );
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK( group->meth->field_mul(&pxt, &tmp, &accr, group->meth) );
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK( group->meth->field_mul(&group->curvea, &pxt, &tmp, group->meth) );
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK( group->meth->field_add(&tmp, &accr, &accr, group->meth) );
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK( group->meth->field_add(&accr, &group->curveb, &accr, group->meth) );
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* check LHS - RHS == 0 */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK( group->meth->field_sub(&accl, &accr, &accr, group->meth) );
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (mp_cmp_z(&accr) != 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        res = MP_NO;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        goto CLEANUP;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* 4: Verify that the order of the curve times the publicValue
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers     *    is the point at infinity.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers     */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK( ECPoint_mul(group, &group->order, px, py, &pxt, &pyt) );
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (ec_GFp_pt_is_inf_aff(&pxt, &pyt) != MP_YES) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        res = MP_NO;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        goto CLEANUP;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    res = MP_YES;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersCLEANUP:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&accl);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&accr);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&tmp);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&pxt);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_clear(&pyt);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return res;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}