text: /* 
   * ***** BEGIN LICENSE BLOCK *****
   * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   *
   * The contents of this file are subject to the Mozilla Public License Version
   * 1.1 (the "License"); you may not use this file except in compliance with
   * the License. You may obtain a copy of the License at
   * http://www.mozilla.org/MPL/
   *
   * Software distributed under the License is distributed on an "AS IS" basis,
   * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
   * for the specific language governing rights and limitations under the
   * License.
   *
   * The Original Code is the elliptic curve math library for binary polynomial field curves.
   *
   * The Initial Developer of the Original Code is
   * Sun Microsystems, Inc.
   * Portions created by the Initial Developer are Copyright (C) 2003
   * the Initial Developer. All Rights Reserved.
   *
   * Contributor(s):
   *   Sheueling Chang-Shantz <sheueling.chang@sun.com>,
   *   Stephen Fung <fungstep@hotmail.com>, and
   *   Douglas Stebila <douglas@stebila.ca>, Sun Microsystems Laboratories.
   *
   * Alternatively, the contents of this file may be used under the terms of
   * either the GNU General Public License Version 2 or later (the "GPL"), or
   * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
   * in which case the provisions of the GPL or the LGPL are applicable instead
   * of those above. If you wish to allow use of your version of this file only
   * under the terms of either the GPL or the LGPL, and not to allow others to
   * use your version of this file under the terms of the MPL, indicate your
   * decision by deleting the provisions above and replace them with the notice
   * and other provisions required by the GPL or the LGPL. If you do not delete
   * the provisions above, a recipient may use your version of this file under
   * the terms of any one of the MPL, the GPL or the LGPL.
   *
   * ***** END LICENSE BLOCK ***** */
  /*
   * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   *
   * Sun elects to use this software under the MPL license.
   */
  
  #include "ec2.h"
  #include "mp_gf2m.h"
  #include "mp_gf2m-priv.h"
  #include "mpi.h"
  #include "mpi-priv.h"
  #ifndef _KERNEL
  #include <stdlib.h>
  #endif
  
  /* Fast reduction for polynomials over a 163-bit curve. Assumes reduction
   * polynomial with terms {163, 7, 6, 3, 0}. */
  mp_err
  ec_GF2m_163_mod(const mp_int *a, mp_int *r, const GFMethod *meth)
  {
  	mp_err res = MP_OKAY;
  	mp_digit *u, z;
  
  	if (a != r) {
  		MP_CHECKOK(mp_copy(a, r));
  	}
  #ifdef ECL_SIXTY_FOUR_BIT
  	if (MP_USED(r) < 6) {
  		MP_CHECKOK(s_mp_pad(r, 6));
  	}
  	u = MP_DIGITS(r);
  	MP_USED(r) = 6;
  
  	/* u[5] only has 6 significant bits */
  	z = u[5];
  	u[2] ^= (z << 36) ^ (z << 35) ^ (z << 32) ^ (z << 29);
  	z = u[4];
  	u[2] ^= (z >> 28) ^ (z >> 29) ^ (z >> 32) ^ (z >> 35);
  	u[1] ^= (z << 36) ^ (z << 35) ^ (z << 32) ^ (z << 29);
  	z = u[3];
  	u[1] ^= (z >> 28) ^ (z >> 29) ^ (z >> 32) ^ (z >> 35);
  	u[0] ^= (z << 36) ^ (z << 35) ^ (z << 32) ^ (z << 29);
  	z = u[2] >> 35;				/* z only has 29 significant bits */
  	u[0] ^= (z << 7) ^ (z << 6) ^ (z << 3) ^ z;
  	/* clear bits above 163 */
  	u[5] = u[4] = u[3] = 0;
  	u[2] ^= z << 35;
  #else
  	if (MP_USED(r) < 11) {
  		MP_CHECKOK(s_mp_pad(r, 11));
  	}
  	u = MP_DIGITS(r);
  	MP_USED(r) = 11;
  
  	/* u[11] only has 6 significant bits */
  	z = u[10];
  	u[5] ^= (z << 4) ^ (z << 3) ^ z ^ (z >> 3);
  	u[4] ^= (z << 29);
  	z = u[9];
  	u[5] ^= (z >> 28) ^ (z >> 29);
  	u[4] ^= (z << 4) ^ (z << 3) ^ z ^ (z >> 3);
  	u[3] ^= (z << 29);
  	z = u[8];
  	u[4] ^= (z >> 28) ^ (z >> 29);
  	u[3] ^= (z << 4) ^ (z << 3) ^ z ^ (z >> 3);
  	u[2] ^= (z << 29);
  	z = u[7];
  	u[3] ^= (z >> 28) ^ (z >> 29);
  	u[2] ^= (z << 4) ^ (z << 3) ^ z ^ (z >> 3);
  	u[1] ^= (z << 29);
  	z = u[6];
  	u[2] ^= (z >> 28) ^ (z >> 29);
  	u[1] ^= (z << 4) ^ (z << 3) ^ z ^ (z >> 3);
  	u[0] ^= (z << 29);
  	z = u[5] >> 3;				/* z only has 29 significant bits */
  	u[1] ^= (z >> 25) ^ (z >> 26);
  	u[0] ^= (z << 7) ^ (z << 6) ^ (z << 3) ^ z;
  	/* clear bits above 163 */
  	u[11] = u[10] = u[9] = u[8] = u[7] = u[6] = 0;
  	u[5] ^= z << 3;
  #endif
  	s_mp_clamp(r);
  
    CLEANUP:
  	return res;
  }
  
  /* Fast squaring for polynomials over a 163-bit curve. Assumes reduction
   * polynomial with terms {163, 7, 6, 3, 0}. */
  mp_err
  ec_GF2m_163_sqr(const mp_int *a, mp_int *r, const GFMethod *meth)
  {
  	mp_err res = MP_OKAY;
  	mp_digit *u, *v;
  
  	v = MP_DIGITS(a);
  
  #ifdef ECL_SIXTY_FOUR_BIT
  	if (MP_USED(a) < 3) {
  		return mp_bsqrmod(a, meth->irr_arr, r);
  	}
  	if (MP_USED(r) < 6) {
  		MP_CHECKOK(s_mp_pad(r, 6));
  	}
  	MP_USED(r) = 6;
  #else
  	if (MP_USED(a) < 6) {
  		return mp_bsqrmod(a, meth->irr_arr, r);
  	}
  	if (MP_USED(r) < 12) {
  		MP_CHECKOK(s_mp_pad(r, 12));
  	}
  	MP_USED(r) = 12;
  #endif
  	u = MP_DIGITS(r);
  
  #ifdef ECL_THIRTY_TWO_BIT
  	u[11] = gf2m_SQR1(v[5]);
  	u[10] = gf2m_SQR0(v[5]);
  	u[9] = gf2m_SQR1(v[4]);
  	u[8] = gf2m_SQR0(v[4]);
  	u[7] = gf2m_SQR1(v[3]);
  	u[6] = gf2m_SQR0(v[3]);
  #endif
  	u[5] = gf2m_SQR1(v[2]);
  	u[4] = gf2m_SQR0(v[2]);
  	u[3] = gf2m_SQR1(v[1]);
  	u[2] = gf2m_SQR0(v[1]);
  	u[1] = gf2m_SQR1(v[0]);
  	u[0] = gf2m_SQR0(v[0]);
  	return ec_GF2m_163_mod(r, r, meth);
  
    CLEANUP:
  	return res;
  }
  
  /* Fast multiplication for polynomials over a 163-bit curve. Assumes
   * reduction polynomial with terms {163, 7, 6, 3, 0}. */
  mp_err
  ec_GF2m_163_mul(const mp_int *a, const mp_int *b, mp_int *r,
  				const GFMethod *meth)
  {
  	mp_err res = MP_OKAY;
  	mp_digit a2 = 0, a1 = 0, a0, b2 = 0, b1 = 0, b0;
  
  #ifdef ECL_THIRTY_TWO_BIT
  	mp_digit a5 = 0, a4 = 0, a3 = 0, b5 = 0, b4 = 0, b3 = 0;
  	mp_digit rm[6];
  #endif
  
  	if (a == b) {
  		return ec_GF2m_163_sqr(a, r, meth);
  	} else {
  		switch (MP_USED(a)) {
  #ifdef ECL_THIRTY_TWO_BIT
  		case 6:
  			a5 = MP_DIGIT(a, 5);
  			/* FALLTHROUGH */
  		case 5:
  			a4 = MP_DIGIT(a, 4);
  			/* FALLTHROUGH */
  		case 4:
  			a3 = MP_DIGIT(a, 3);
  #endif
  			/* FALLTHROUGH */
  		case 3:
  			a2 = MP_DIGIT(a, 2);
  			/* FALLTHROUGH */
  		case 2:
  			a1 = MP_DIGIT(a, 1);
  			/* FALLTHROUGH */
  		default:
  			a0 = MP_DIGIT(a, 0);
  		}
  		switch (MP_USED(b)) {
  #ifdef ECL_THIRTY_TWO_BIT
  		case 6:
  			b5 = MP_DIGIT(b, 5);
  			/* FALLTHROUGH */
  		case 5:
  			b4 = MP_DIGIT(b, 4);
  			/* FALLTHROUGH */
  		case 4:
  			b3 = MP_DIGIT(b, 3);
  #endif
  			/* FALLTHROUGH */
  		case 3:
  			b2 = MP_DIGIT(b, 2);
  			/* FALLTHROUGH */
  		case 2:
  			b1 = MP_DIGIT(b, 1);
  			/* FALLTHROUGH */
  		default:
  			b0 = MP_DIGIT(b, 0);
  		}
  #ifdef ECL_SIXTY_FOUR_BIT
  		MP_CHECKOK(s_mp_pad(r, 6));
  		s_bmul_3x3(MP_DIGITS(r), a2, a1, a0, b2, b1, b0);
  		MP_USED(r) = 6;
  		s_mp_clamp(r);
  #else
  		MP_CHECKOK(s_mp_pad(r, 12));
  		s_bmul_3x3(MP_DIGITS(r) + 6, a5, a4, a3, b5, b4, b3);
  		s_bmul_3x3(MP_DIGITS(r), a2, a1, a0, b2, b1, b0);
  		s_bmul_3x3(rm, a5 ^ a2, a4 ^ a1, a3 ^ a0, b5 ^ b2, b4 ^ b1,
  				   b3 ^ b0);
  		rm[5] ^= MP_DIGIT(r, 5) ^ MP_DIGIT(r, 11);
  		rm[4] ^= MP_DIGIT(r, 4) ^ MP_DIGIT(r, 10);
  		rm[3] ^= MP_DIGIT(r, 3) ^ MP_DIGIT(r, 9);
  		rm[2] ^= MP_DIGIT(r, 2) ^ MP_DIGIT(r, 8);
  		rm[1] ^= MP_DIGIT(r, 1) ^ MP_DIGIT(r, 7);
  		rm[0] ^= MP_DIGIT(r, 0) ^ MP_DIGIT(r, 6);
  		MP_DIGIT(r, 8) ^= rm[5];
  		MP_DIGIT(r, 7) ^= rm[4];
  		MP_DIGIT(r, 6) ^= rm[3];
  		MP_DIGIT(r, 5) ^= rm[2];
  		MP_DIGIT(r, 4) ^= rm[1];
  		MP_DIGIT(r, 3) ^= rm[0];
  		MP_USED(r) = 12;
  		s_mp_clamp(r);
  #endif
  		return ec_GF2m_163_mod(r, r, meth);
  	}
  
    CLEANUP:
  	return res;
  }
  
  /* Wire in fast field arithmetic for 163-bit curves. */
  mp_err
  ec_group_set_gf2m163(ECGroup *group, ECCurveName name)
  {
  	group->meth->field_mod = &ec_GF2m_163_mod;
  	group->meth->field_mul = &ec_GF2m_163_mul;
  	group->meth->field_sqr = &ec_GF2m_163_sqr;
  	return MP_OKAY;
  }
  