michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "ec2.h"
michael@0: #include "mp_gf2m.h"
michael@0: #include "mp_gf2m-priv.h"
michael@0: #include "mpi.h"
michael@0: #include "mpi-priv.h"
michael@0: #include <stdlib.h>
michael@0: 
michael@0: /* Fast reduction for polynomials over a 193-bit curve. Assumes reduction
michael@0:  * polynomial with terms {193, 15, 0}. */
michael@0: mp_err
michael@0: ec_GF2m_193_mod(const mp_int *a, mp_int *r, const GFMethod *meth)
michael@0: {
michael@0: 	mp_err res = MP_OKAY;
michael@0: 	mp_digit *u, z;
michael@0: 
michael@0: 	if (a != r) {
michael@0: 		MP_CHECKOK(mp_copy(a, r));
michael@0: 	}
michael@0: #ifdef ECL_SIXTY_FOUR_BIT
michael@0: 	if (MP_USED(r) < 7) {
michael@0: 		MP_CHECKOK(s_mp_pad(r, 7));
michael@0: 	}
michael@0: 	u = MP_DIGITS(r);
michael@0: 	MP_USED(r) = 7;
michael@0: 
michael@0: 	/* u[6] only has 2 significant bits */
michael@0: 	z = u[6];
michael@0: 	u[3] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[2] ^= (z << 63);
michael@0: 	z = u[5];
michael@0: 	u[3] ^= (z >> 50);
michael@0: 	u[2] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[1] ^= (z << 63);
michael@0: 	z = u[4];
michael@0: 	u[2] ^= (z >> 50);
michael@0: 	u[1] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[0] ^= (z << 63);
michael@0: 	z = u[3] >> 1;				/* z only has 63 significant bits */
michael@0: 	u[1] ^= (z >> 49);
michael@0: 	u[0] ^= (z << 15) ^ z;
michael@0: 	/* clear bits above 193 */
michael@0: 	u[6] = u[5] = u[4] = 0;
michael@0: 	u[3] ^= z << 1;
michael@0: #else
michael@0: 	if (MP_USED(r) < 13) {
michael@0: 		MP_CHECKOK(s_mp_pad(r, 13));
michael@0: 	}
michael@0: 	u = MP_DIGITS(r);
michael@0: 	MP_USED(r) = 13;
michael@0: 
michael@0: 	/* u[12] only has 2 significant bits */
michael@0: 	z = u[12];
michael@0: 	u[6] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[5] ^= (z << 31);
michael@0: 	z = u[11];
michael@0: 	u[6] ^= (z >> 18);
michael@0: 	u[5] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[4] ^= (z << 31);
michael@0: 	z = u[10];
michael@0: 	u[5] ^= (z >> 18);
michael@0: 	u[4] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[3] ^= (z << 31);
michael@0: 	z = u[9];
michael@0: 	u[4] ^= (z >> 18);
michael@0: 	u[3] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[2] ^= (z << 31);
michael@0: 	z = u[8];
michael@0: 	u[3] ^= (z >> 18);
michael@0: 	u[2] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[1] ^= (z << 31);
michael@0: 	z = u[7];
michael@0: 	u[2] ^= (z >> 18);
michael@0: 	u[1] ^= (z << 14) ^ (z >> 1);
michael@0: 	u[0] ^= (z << 31);
michael@0: 	z = u[6] >> 1;				/* z only has 31 significant bits */
michael@0: 	u[1] ^= (z >> 17);
michael@0: 	u[0] ^= (z << 15) ^ z;
michael@0: 	/* clear bits above 193 */
michael@0: 	u[12] = u[11] = u[10] = u[9] = u[8] = u[7] = 0;
michael@0: 	u[6] ^= z << 1;
michael@0: #endif
michael@0: 	s_mp_clamp(r);
michael@0: 
michael@0:   CLEANUP:
michael@0: 	return res;
michael@0: }
michael@0: 
michael@0: /* Fast squaring for polynomials over a 193-bit curve. Assumes reduction
michael@0:  * polynomial with terms {193, 15, 0}. */
michael@0: mp_err
michael@0: ec_GF2m_193_sqr(const mp_int *a, mp_int *r, const GFMethod *meth)
michael@0: {
michael@0: 	mp_err res = MP_OKAY;
michael@0: 	mp_digit *u, *v;
michael@0: 
michael@0: 	v = MP_DIGITS(a);
michael@0: 
michael@0: #ifdef ECL_SIXTY_FOUR_BIT
michael@0: 	if (MP_USED(a) < 4) {
michael@0: 		return mp_bsqrmod(a, meth->irr_arr, r);
michael@0: 	}
michael@0: 	if (MP_USED(r) < 7) {
michael@0: 		MP_CHECKOK(s_mp_pad(r, 7));
michael@0: 	}
michael@0: 	MP_USED(r) = 7;
michael@0: #else
michael@0: 	if (MP_USED(a) < 7) {
michael@0: 		return mp_bsqrmod(a, meth->irr_arr, r);
michael@0: 	}
michael@0: 	if (MP_USED(r) < 13) {
michael@0: 		MP_CHECKOK(s_mp_pad(r, 13));
michael@0: 	}
michael@0: 	MP_USED(r) = 13;
michael@0: #endif
michael@0: 	u = MP_DIGITS(r);
michael@0: 
michael@0: #ifdef ECL_THIRTY_TWO_BIT
michael@0: 	u[12] = gf2m_SQR0(v[6]);
michael@0: 	u[11] = gf2m_SQR1(v[5]);
michael@0: 	u[10] = gf2m_SQR0(v[5]);
michael@0: 	u[9] = gf2m_SQR1(v[4]);
michael@0: 	u[8] = gf2m_SQR0(v[4]);
michael@0: 	u[7] = gf2m_SQR1(v[3]);
michael@0: #endif
michael@0: 	u[6] = gf2m_SQR0(v[3]);
michael@0: 	u[5] = gf2m_SQR1(v[2]);
michael@0: 	u[4] = gf2m_SQR0(v[2]);
michael@0: 	u[3] = gf2m_SQR1(v[1]);
michael@0: 	u[2] = gf2m_SQR0(v[1]);
michael@0: 	u[1] = gf2m_SQR1(v[0]);
michael@0: 	u[0] = gf2m_SQR0(v[0]);
michael@0: 	return ec_GF2m_193_mod(r, r, meth);
michael@0: 
michael@0:   CLEANUP:
michael@0: 	return res;
michael@0: }
michael@0: 
michael@0: /* Fast multiplication for polynomials over a 193-bit curve. Assumes
michael@0:  * reduction polynomial with terms {193, 15, 0}. */
michael@0: mp_err
michael@0: ec_GF2m_193_mul(const mp_int *a, const mp_int *b, mp_int *r,
michael@0: 				const GFMethod *meth)
michael@0: {
michael@0: 	mp_err res = MP_OKAY;
michael@0: 	mp_digit a3 = 0, a2 = 0, a1 = 0, a0, b3 = 0, b2 = 0, b1 = 0, b0;
michael@0: 
michael@0: #ifdef ECL_THIRTY_TWO_BIT
michael@0: 	mp_digit a6 = 0, a5 = 0, a4 = 0, b6 = 0, b5 = 0, b4 = 0;
michael@0: 	mp_digit rm[8];
michael@0: #endif
michael@0: 
michael@0: 	if (a == b) {
michael@0: 		return ec_GF2m_193_sqr(a, r, meth);
michael@0: 	} else {
michael@0: 		switch (MP_USED(a)) {
michael@0: #ifdef ECL_THIRTY_TWO_BIT
michael@0: 		case 7:
michael@0: 			a6 = MP_DIGIT(a, 6);
michael@0: 		case 6:
michael@0: 			a5 = MP_DIGIT(a, 5);
michael@0: 		case 5:
michael@0: 			a4 = MP_DIGIT(a, 4);
michael@0: #endif
michael@0: 		case 4:
michael@0: 			a3 = MP_DIGIT(a, 3);
michael@0: 		case 3:
michael@0: 			a2 = MP_DIGIT(a, 2);
michael@0: 		case 2:
michael@0: 			a1 = MP_DIGIT(a, 1);
michael@0: 		default:
michael@0: 			a0 = MP_DIGIT(a, 0);
michael@0: 		}
michael@0: 		switch (MP_USED(b)) {
michael@0: #ifdef ECL_THIRTY_TWO_BIT
michael@0: 		case 7:
michael@0: 			b6 = MP_DIGIT(b, 6);
michael@0: 		case 6:
michael@0: 			b5 = MP_DIGIT(b, 5);
michael@0: 		case 5:
michael@0: 			b4 = MP_DIGIT(b, 4);
michael@0: #endif
michael@0: 		case 4:
michael@0: 			b3 = MP_DIGIT(b, 3);
michael@0: 		case 3:
michael@0: 			b2 = MP_DIGIT(b, 2);
michael@0: 		case 2:
michael@0: 			b1 = MP_DIGIT(b, 1);
michael@0: 		default:
michael@0: 			b0 = MP_DIGIT(b, 0);
michael@0: 		}
michael@0: #ifdef ECL_SIXTY_FOUR_BIT
michael@0: 		MP_CHECKOK(s_mp_pad(r, 8));
michael@0: 		s_bmul_4x4(MP_DIGITS(r), a3, a2, a1, a0, b3, b2, b1, b0);
michael@0: 		MP_USED(r) = 8;
michael@0: 		s_mp_clamp(r);
michael@0: #else
michael@0: 		MP_CHECKOK(s_mp_pad(r, 14));
michael@0: 		s_bmul_3x3(MP_DIGITS(r) + 8, a6, a5, a4, b6, b5, b4);
michael@0: 		s_bmul_4x4(MP_DIGITS(r), a3, a2, a1, a0, b3, b2, b1, b0);
michael@0: 		s_bmul_4x4(rm, a3, a6 ^ a2, a5 ^ a1, a4 ^ a0, b3, b6 ^ b2, b5 ^ b1,
michael@0: 				   b4 ^ b0);
michael@0: 		rm[7] ^= MP_DIGIT(r, 7);
michael@0: 		rm[6] ^= MP_DIGIT(r, 6);
michael@0: 		rm[5] ^= MP_DIGIT(r, 5) ^ MP_DIGIT(r, 13);
michael@0: 		rm[4] ^= MP_DIGIT(r, 4) ^ MP_DIGIT(r, 12);
michael@0: 		rm[3] ^= MP_DIGIT(r, 3) ^ MP_DIGIT(r, 11);
michael@0: 		rm[2] ^= MP_DIGIT(r, 2) ^ MP_DIGIT(r, 10);
michael@0: 		rm[1] ^= MP_DIGIT(r, 1) ^ MP_DIGIT(r, 9);
michael@0: 		rm[0] ^= MP_DIGIT(r, 0) ^ MP_DIGIT(r, 8);
michael@0: 		MP_DIGIT(r, 11) ^= rm[7];
michael@0: 		MP_DIGIT(r, 10) ^= rm[6];
michael@0: 		MP_DIGIT(r, 9) ^= rm[5];
michael@0: 		MP_DIGIT(r, 8) ^= rm[4];
michael@0: 		MP_DIGIT(r, 7) ^= rm[3];
michael@0: 		MP_DIGIT(r, 6) ^= rm[2];
michael@0: 		MP_DIGIT(r, 5) ^= rm[1];
michael@0: 		MP_DIGIT(r, 4) ^= rm[0];
michael@0: 		MP_USED(r) = 14;
michael@0: 		s_mp_clamp(r);
michael@0: #endif
michael@0: 		return ec_GF2m_193_mod(r, r, meth);
michael@0: 	}
michael@0: 
michael@0:   CLEANUP:
michael@0: 	return res;
michael@0: }
michael@0: 
michael@0: /* Wire in fast field arithmetic for 193-bit curves. */
michael@0: mp_err
michael@0: ec_group_set_gf2m193(ECGroup *group, ECCurveName name)
michael@0: {
michael@0: 	group->meth->field_mod = &ec_GF2m_193_mod;
michael@0: 	group->meth->field_mul = &ec_GF2m_193_mul;
michael@0: 	group->meth->field_sqr = &ec_GF2m_193_sqr;
michael@0: 	return MP_OKAY;
michael@0: }