/*

 * RELIC is an Efficient LIbrary for Cryptography

 * Copyright (c) 2014 RELIC Authors

 *

 * This file is part of RELIC. RELIC is legal property of its developers,

 * whose names are not listed here. Please refer to the COPYRIGHT file

 * for contact information.

 *

 * RELIC is free software; you can redistribute it and/or modify it under the

 * terms of the version 2.1 (or later) of the GNU Lesser General Public License

 * as published by the Free Software Foundation; or version 2.0 of the Apache

 * License as published by the Apache Software Foundation. See the LICENSE files

 * for more details.

 *

 * RELIC is distributed in the hope that it will be useful, but WITHOUT ANY

 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR

 * A PARTICULAR PURPOSE. See the LICENSE files for more details.

 *

 * You should have received a copy of the GNU Lesser General Public or the

 * Apache License along with RELIC. If not, see <https://www.gnu.org/licenses/>

 * or <https://www.apache.org/licenses/>.

 */

/**

* @file

*

* Implementation of the point doubling on prime elliptic twisted Edwards curves.

*

* @version $Id$

* @ingroup ed

*/

#include "relic_core.h"

#include "relic_label.h"

/*============================================================================*/

/* Public definitions                                                         */

/*============================================================================*/

#if ED_ADD == BASIC || !defined(STRIP)

void ed_dbl_basic(ed_t r, const ed_t p) {

  fp_t t0, t1, t2;

  fp_null(t0);

  fp_null(t1);

  fp_null(t2);

  RLC_TRY {

    fp_new(t0);

    fp_new(t1);

    fp_new(t2);

    /* x3 = (x1*y1+y1*x1)/(1+d*x1*x1*y1*y1)

     * y3 = (y1*y1-a*x1*x1)/(1-d*x1*x1*y1*y1) */

    fp_mul(t0, p->x, p->y);

    fp_sqr(t1, t0);

    fp_mul(t1, t1, core_get()->ed_d);

    fp_add_dig(t2, t1, 1);

    fp_inv(t2, t2);

    fp_sub_dig(t1, t1, 1);

    fp_neg(t1, t1);

    fp_inv(t1, t1);

    fp_dbl(t0, t0);

    fp_mul(t0, t0, t2);

    fp_sqr(t2, p->x);

    fp_mul(t2, t2, core_get()->ed_a);

    fp_sqr(r->y, p->y);

    fp_sub(r->y, r->y, t2);

    fp_mul(r->y, r->y, t1);

    fp_copy(r->x, t0);

    fp_copy(r->z, p->z);

    r->coord = BASIC;

  }

  RLC_CATCH_ANY {

    RLC_THROW(ERR_CAUGHT);

  }

  RLC_FINALLY {

    fp_free(t0);

    fp_free(t1);

    fp_free(t2);

  }

}

#endif /* ED_ADD == BASIC */

#if ED_ADD == PROJC || !defined(STRIP)

void ed_dbl_projc(ed_t r, const ed_t p) {

  fp_t t0, t1, t2, t3, t4, t5, t6;

  fp_null(t0);

  fp_null(t1);

  fp_null(t2);

  fp_null(t3);

  fp_null(t4);

  fp_null(t5);

  fp_null(t6);

  RLC_TRY {

    fp_new(t0);

    fp_new(t1);

    fp_new(t2);

    fp_new(t3);

    fp_new(t4);

    fp_new(t5);

    fp_new(t6);

    // 3M + 4S + 1D + 7add

    /* B = (x1 + y1)^2 */

    fp_add(t0, p->x, p->y);

    fp_sqr(t0, t0);

    /* C = x1^2 */

    fp_sqr(t1, p->x);

    /*  D = y1^2 */

    fp_sqr(t2, p->y);

    /* E = a * C */

    fp_mul(t3, core_get()->ed_a, t1);

    /* F = E + D, H = Z^2 */

    fp_add(t4, t3, t2);

    fp_sqr(t5, p->z);

    // J = F - 2H

    fp_dbl(t6, t5);

    fp_sub(t6, t4, t6);

    // x3 = (B - C - D) * J

    fp_sub(r->x, t0, t1);

    fp_sub(r->x, r->x, t2);

    fp_mul(r->x, r->x, t6);

    // x3 = F * (E - D)

    fp_sub(r->y, t3, t2);

    fp_mul(r->y, t4, r->y);

    /* x3 = F * J */

    fp_mul(r->z, t4, t6);

    r->coord = PROJC;

  } RLC_CATCH_ANY {

    RLC_THROW(ERR_CAUGHT);

  } RLC_FINALLY {

    fp_free(t0);

    fp_free(t1);

    fp_free(t2);

    fp_free(t3);

    fp_free(t4);

    fp_free(t5);

    fp_free(t6);

  }

}

#endif /* ED_PROJC */

#if ED_ADD == EXTND || !defined(STRIP)

void ed_dbl_extnd(ed_t r, const ed_t p) {

  fp_t t0, t1, t2, t3, t4;

  fp_null(t0);

  fp_null(t1);

  fp_null(t2);

  fp_null(t3);

  fp_null(t4);

  RLC_TRY {

    fp_new(t0);

    fp_new(t1);

    fp_new(t2);

    fp_new(t3);

    fp_new(t4);

    // efd: dbl-2008-hwcd, rfc edition

    // 4M + 4S + 1D + 7add

    /* A = X^2, B = Y^2 */

    fp_sqr(t0, p->x);

    fp_sqr(t1, p->y);

    /* C = 2 * Z^2 */

    fp_sqr(r->z, p->z);

    fp_dbl(r->z, r->z);

    /* D = a * A */

    fp_mul(r->t, core_get()->ed_a, t0);

    /* E = (X + Y) ^ 2 - A - B */

    fp_add(t2, p->x, p->y);

    fp_sqr(t2, t2);

    fp_sub(t2, t2, t0);

    fp_sub(t2, t2, t1);

    /* G = D + B, F = G - C, H = D - B */

    fp_add(t4, r->t, t1);

    fp_sub(t3, t4, r->z);

    fp_sub(r->z, r->t, t1);

    /* X = E * F */

    fp_mul(r->x, t2, t3);

    /* Y = G * H */

    fp_mul(r->y, t4, r->z);

    /* T = E * H */

    fp_mul(r->t, t2, r->z);

    /* Z = F * G */

    fp_mul(r->z, t3, t4);

    r->coord = EXTND;

  } RLC_CATCH_ANY {

    RLC_THROW(ERR_CAUGHT);

  } RLC_FINALLY {

    fp_free(t0);

    fp_free(t1);

    fp_free(t2);

    fp_free(t3);

    fp_free(t4);

  }

}

#endif /* ED_EXTND */