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 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 #include "ec2.h"

 #include "mp_gf2m.h"

 #include "mp_gf2m-priv.h"

 #include "mpi.h"

 #include "mpi-priv.h"

 #include <stdlib.h>

 /* 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);

 		case 5:

 			a4 = MP_DIGIT(a, 4);

 		case 4:

 			a3 = MP_DIGIT(a, 3);

 #endif

 		case 3:

 			a2 = MP_DIGIT(a, 2);

 		case 2:

 			a1 = MP_DIGIT(a, 1);

 		default:

 			a0 = MP_DIGIT(a, 0);

 		}

 		switch (MP_USED(b)) {

 #ifdef ECL_THIRTY_TWO_BIT

 		case 6:

 			b5 = MP_DIGIT(b, 5);

 		case 5:

 			b4 = MP_DIGIT(b, 4);

 		case 4:

 			b3 = MP_DIGIT(b, 3);

 #endif

 		case 3:

 			b2 = MP_DIGIT(b, 2);

 		case 2:

 			b1 = MP_DIGIT(b, 1);

 		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;

 }