/*

 *  Copyright (C) 2017 - This file is part of libecc project

 *

 *  Authors:

 *      Ryad BENADJILA <ryadbenadjila@gmail.com>

 *      Arnaud EBALARD <arnaud.ebalard@ssi.gouv.fr>

 *      Jean-Pierre FLORI <jean-pierre.flori@ssi.gouv.fr>

 *

 *  Contributors:

 *      Nicolas VIVET <nicolas.vivet@ssi.gouv.fr>

 *      Karim KHALFALLAH <karim.khalfallah@ssi.gouv.fr>

 *

 *  This software is licensed under a dual BSD and GPL v2 license.

 *  See LICENSE file at the root folder of the project.

 */

#include <libecc/fp/fp_mul_redc1.h>

/*

 * Internal helper performing Montgomery multiplication. The function returns

 * 0 on success, -1 on error.

 *

 * CAUTION: the function does not check input parameters. Those checks MUST be

 * performed by the caller.

 */

ATTRIBUTE_WARN_UNUSED_RET static inline int _fp_mul_redc1(nn_t out, nn_src_t in1, nn_src_t in2,

         fp_ctx_src_t ctx)

{

  return nn_mul_redc1(out, in1, in2, &(ctx->p), ctx->mpinv);

}

/*

 * Compute out = in1 * in2 mod (p) in redcified form.

 *

 * Exported version based on previous one, that sanity checks input parameters.

 * The function returns 0 on success, -1 on error.

 *

 * Aliasing is supported.

 */

int fp_mul_redc1(fp_t out, fp_src_t in1, fp_src_t in2)

{

  int ret;

  ret = fp_check_initialized(in1); EG(ret, err);

  ret = fp_check_initialized(in2); EG(ret, err);

  ret = fp_check_initialized(out); EG(ret, err);

  MUST_HAVE((out->ctx == in1->ctx), ret, err);

  MUST_HAVE((out->ctx == in2->ctx), ret, err);

  ret = _fp_mul_redc1(&(out->fp_val), &(in1->fp_val), &(in2->fp_val),

          out->ctx);

err:

  return ret;

}

/*

 * Compute out = in * in mod (p) in redcified form.

 *

 * Aliasing is supported.

 */

int fp_sqr_redc1(fp_t out, fp_src_t in)

{

  return fp_mul_redc1(out, in, in);

}

/*

 * Compute out = redcified form of in.

 * redcify could be done by shifting and division by p. The function returns 0

 * on success, -1 on error.

 *

 * Aliasing is supported.

 */

int fp_redcify(fp_t out, fp_src_t in)

{

  int ret;

  ret = fp_check_initialized(in); EG(ret, err);

  ret = fp_check_initialized(out); EG(ret, err);

  MUST_HAVE((out->ctx == in->ctx), ret, err);

  ret = _fp_mul_redc1(&(out->fp_val), &(in->fp_val), &(out->ctx->r_square),

          out->ctx);

err:

  return ret;

}

/*

 * Compute out = unredcified form of in.

 * The function returns 0 on success, -1 on error.

 *

 * Aliasing is supported.

 */

int fp_unredcify(fp_t out, fp_src_t in)

{

  int ret;

  nn one;

  one.magic = WORD(0);

  ret = fp_check_initialized(in); EG(ret, err);

  ret = fp_check_initialized(out); EG(ret, err);

  ret = nn_init(&one, 0);  EG(ret, err);

  ret = nn_one(&one); EG(ret, err);

  ret = _fp_mul_redc1(&(out->fp_val), &(in->fp_val), &one, out->ctx);

err:

  nn_uninit(&one);

  return ret;

}