crypto/ecc/ecp_224.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 *   Douglas Stebila <douglas@stebila.ca>, Sun Microsystems Laboratories
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 "mpi.h"
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#include "mplogic.h"
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#include "mpi-priv.h"
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#ifndef _KERNEL
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#include <stdlib.h>
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#endif
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#define ECP224_DIGITS ECL_CURVE_DIGITS(224)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Fast modular reduction for p224 = 2^224 - 2^96 + 1.  a can be r. Uses
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * algorithm 7 from Brown, Hankerson, Lopez, Menezes. Software
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Implementation of the NIST Elliptic Curves over Prime Fields. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_nistp224_mod(const mp_int *a, mp_int *r, const GFMethod *meth)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_err res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_size a_used = MP_USED(a);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    int    r3b;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_digit carry;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#ifdef ECL_THIRTY_TWO_BIT
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_digit a6a = 0, a6b = 0,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                a5a = 0, a5b = 0, a4a = 0, a4b = 0, a3a = 0, a3b = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_digit r0a, r0b, r1a, r1b, r2a, r2b, r3a;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#else
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_digit a6 = 0, a5 = 0, a4 = 0, a3b = 0, a5a = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_digit a6b = 0, a6a_a5b = 0, a5b = 0, a5a_a4b = 0, a4a_a3b = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_digit r0, r1, r2, r3;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#endif
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* reduction not needed if a is not larger than field size */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (a_used < ECP224_DIGITS) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (a == r) return MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        return mp_copy(a, r);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* for polynomials larger than twice the field size, use regular
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers     * reduction */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (a_used > ECL_CURVE_DIGITS(224*2)) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_mod(a, &meth->irr, r));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    } else {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#ifdef ECL_THIRTY_TWO_BIT
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* copy out upper words of a */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        switch (a_used) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 14:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a6b = MP_DIGIT(a, 13);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 13:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a6a = MP_DIGIT(a, 12);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 12:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a5b = MP_DIGIT(a, 11);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 11:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a5a = MP_DIGIT(a, 10);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 10:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a4b = MP_DIGIT(a, 9);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 9:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a4a = MP_DIGIT(a, 8);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 8:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a3b = MP_DIGIT(a, 7);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r3a = MP_DIGIT(a, 6);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r2b= MP_DIGIT(a, 5);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r2a= MP_DIGIT(a, 4);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r1b = MP_DIGIT(a, 3);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r1a = MP_DIGIT(a, 2);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r0b = MP_DIGIT(a, 1);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r0a = MP_DIGIT(a, 0);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* implement r = (a3a,a2,a1,a0)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            +(a5a, a4,a3b,  0)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            +(  0, a6,a5b,  0)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            -(  0    0,    0|a6b, a6a|a5b )
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            -(  a6b, a6a|a5b, a5a|a4b, a4a|a3b ) */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r1b, a3b, r1b, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r2a, a4a, r2a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r2b, a4b, r2b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r3a, a5a, r3a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r3b = carry;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r1b, a5b, r1b, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r2a, a6a, r2a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r2b, a6b, r2b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r3a,   0, r3a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r3b += carry;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r0a, a3b, r0a, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r0b, a4a, r0b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r1a, a4b, r1a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r1b, a5a, r1b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r2a, a5b, r2a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r2b, a6a, r2b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r3a, a6b, r3a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r3b -= carry;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r0a, a5b, r0a, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r0b, a6a, r0b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r1a, a6b, r1a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (carry) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r1b, 0, r1b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r2a, 0, r2a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r2b, 0, r2b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r3a, 0, r3a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            r3b -= carry;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        while (r3b > 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            int tmp;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_ADD_CARRY(r1b, r3b, r1b, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            if (carry) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_ADD_CARRY(r2a,  0, r2a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_ADD_CARRY(r2b,  0, r2b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_ADD_CARRY(r3a,  0, r3a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            tmp = carry;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r0a, r3b, r0a, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            if (carry) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r0b, 0, r0b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r1a, 0, r1a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r1b, 0, r1b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r2a, 0, r2a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r2b, 0, r2b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r3a, 0, r3a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                tmp -= carry;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            r3b = tmp;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        while (r3b < 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            mp_digit maxInt = MP_DIGIT_MAX;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r0a, 1, r0a, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r0b, 0, r0b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r1a, 0, r1a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r1b, maxInt, r1b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r2a, maxInt, r2a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r2b, maxInt, r2b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r3a, maxInt, r3a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            r3b += carry;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* check for final reduction */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* now the only way we are over is if the top 4 words are all ones */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if ((r3a == MP_DIGIT_MAX) && (r2b == MP_DIGIT_MAX)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            && (r2a == MP_DIGIT_MAX) && (r1b == MP_DIGIT_MAX) &&
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers             ((r1a != 0) || (r0b != 0) || (r0a != 0)) ) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            /* one last subraction */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r0a, 1, r0a, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r0b, 0, r0b, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r1a, 0, r1a, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            r1b = r2a = r2b = r3a = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (a != r) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_CHECKOK(s_mp_pad(r, 7));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* set the lower words of r */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SIGN(r) = MP_ZPOS;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_USED(r) = 7;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 6) = r3a;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 5) = r2b;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 4) = r2a;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 3) = r1b;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 2) = r1a;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 1) = r0b;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 0) = r0a;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#else
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* copy out upper words of a */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        switch (a_used) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 7:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a6 = MP_DIGIT(a, 6);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a6b = a6 >> 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a6a_a5b = a6 << 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 6:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a5 = MP_DIGIT(a, 5);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a5b = a5 >> 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a6a_a5b |= a5b;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a5b = a5b << 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a5a_a4b = a5 << 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a5a = a5 & 0xffffffff;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 5:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a4 = MP_DIGIT(a, 4);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a5a_a4b |= a4 >> 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a4a_a3b = a4 << 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        case 4:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a3b = MP_DIGIT(a, 3) >> 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a4a_a3b |= a3b;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            a3b = a3b << 32;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r3 = MP_DIGIT(a, 3) & 0xffffffff;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r2 = MP_DIGIT(a, 2);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r1 = MP_DIGIT(a, 1);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r0 = MP_DIGIT(a, 0);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* implement r = (a3a,a2,a1,a0)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            +(a5a, a4,a3b,  0)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            +(  0, a6,a5b,  0)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            -(  0    0,    0|a6b, a6a|a5b )
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            -(  a6b, a6a|a5b, a5a|a4b, a4a|a3b ) */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r1, a3b, r1, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r2, a4 , r2, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r3, a5a, r3, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r1, a5b, r1, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r2, a6 , r2, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_ADD_CARRY (r3,   0, r3, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r0, a4a_a3b, r0, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r1, a5a_a4b, r1, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r2, a6a_a5b, r2, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r3, a6b    , r3, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r0, a6a_a5b, r0, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SUB_BORROW(r1, a6b    , r1, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (carry) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r2, 0, r2, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r3, 0, r3, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* if the value is negative, r3 has a 2's complement
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers         * high value */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        r3b = (int)(r3 >>32);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        while (r3b > 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            r3 &= 0xffffffff;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_ADD_CARRY(r1,((mp_digit)r3b) << 32, r1, 0, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            if (carry) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_ADD_CARRY(r2,  0, r2, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_ADD_CARRY(r3,  0, r3, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r0, r3b, r0, 0, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            if (carry) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r1, 0, r1, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r2, 0, r2, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                MP_SUB_BORROW(r3, 0, r3, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            r3b = (int)(r3 >>32);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        while (r3b < 0) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r0, 1, r0, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r1, MP_DIGIT_MAX <<32, r1, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r2, MP_DIGIT_MAX, r2, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    MP_ADD_CARRY (r3, MP_DIGIT_MAX >> 32, r3, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            r3b = (int)(r3 >>32);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* check for final reduction */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* now the only way we are over is if the top 4 words are all ones */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if ((r3 == (MP_DIGIT_MAX >> 32)) && (r2 == MP_DIGIT_MAX)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            && ((r1 & MP_DIGIT_MAX << 32)== MP_DIGIT_MAX << 32) &&
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers             ((r1 != MP_DIGIT_MAX << 32 ) || (r0 != 0)) ) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            /* one last subraction */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r0, 1, r0, 0,     carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_SUB_BORROW(r1, 0, r1, carry, carry);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            r2 = r3 = 0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        if (a != r) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers            MP_CHECKOK(s_mp_pad(r, 4));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* set the lower words of r */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_SIGN(r) = MP_ZPOS;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_USED(r) = 4;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 3) = r3;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 2) = r2;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 1) = r1;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_DIGIT(r, 0) = r0;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers#endif
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers  CLEANUP:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return res;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Compute the square of polynomial a, reduce modulo p224. Store the
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * result in r.  r could be a.  Uses optimized modular reduction for p224.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_nistp224_sqr(const mp_int *a, mp_int *r, const GFMethod *meth)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_err res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_sqr(a, r));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(ec_GFp_nistp224_mod(r, r, meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers  CLEANUP:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return res;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Compute the product of two polynomials a and b, reduce modulo p224.
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * Store the result in r.  r could be a or b; a could be b.  Uses
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * optimized modular reduction for p224. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_nistp224_mul(const mp_int *a, const mp_int *b, mp_int *r,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers                    const GFMethod *meth)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_err res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(mp_mul(a, b, r));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    MP_CHECKOK(ec_GFp_nistp224_mod(r, r, meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers  CLEANUP:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return res;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Divides two field elements. If a is NULL, then returns the inverse of
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * b. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_GFp_nistp224_div(const mp_int *a, const mp_int *b, mp_int *r,
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers           const GFMethod *meth)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_err res = MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    mp_int t;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    /* If a is NULL, then return the inverse of b, otherwise return a/b. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (a == NULL) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        return  mp_invmod(b, &meth->irr, r);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    } else {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        /* MPI doesn't support divmod, so we implement it using invmod and
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers         * mulmod. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_init(&t, FLAG(b)));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_invmod(b, &meth->irr, &t));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(mp_mul(a, &t, r));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        MP_CHECKOK(ec_GFp_nistp224_mod(r, r, meth));
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers      CLEANUP:
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        mp_clear(&t);
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        return res;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers/* Wire in fast field arithmetic and precomputation of base point for
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers * named curves. */
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersmp_err
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowersec_group_set_gfp224(ECGroup *group, ECCurveName name)
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers{
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    if (name == ECCurve_NIST_P224) {
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        group->meth->field_mod = &ec_GFp_nistp224_mod;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        group->meth->field_mul = &ec_GFp_nistp224_mul;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        group->meth->field_sqr = &ec_GFp_nistp224_sqr;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers        group->meth->field_div = &ec_GFp_nistp224_div;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    }
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers    return MP_OKAY;
f9fbec18f5b458b560ecf45d3db8e8bd56bf6942mcpowers}