1  /*
  2   *  Copyright (C) 2017 - This file is part of libecc project
  3   *
  4   *  Authors:
  5   *      Ryad BENADJILA <ryadbenadjila@gmail.com>
  6   *      Arnaud EBALARD <arnaud.ebalard@ssi.gouv.fr>
  7   *      Jean-Pierre FLORI <jean-pierre.flori@ssi.gouv.fr>
  8   *
  9   *  Contributors:
 10   *      Nicolas VIVET <nicolas.vivet@ssi.gouv.fr>
 11   *      Karim KHALFALLAH <karim.khalfallah@ssi.gouv.fr>
 12   *
 13   *  This software is licensed under a dual BSD and GPL v2 license.
 14   *  See LICENSE file at the root folder of the project.
 15   */
 16  #include <libecc/fp/fp_mul_redc1.h>
 17  
 18  /*
 19   * Internal helper performing Montgomery multiplication. The function returns
 20   * 0 on success, -1 on error.
 21   *
 22   * CAUTION: the function does not check input parameters. Those checks MUST be
 23   * performed by the caller.
 24   */
 25  ATTRIBUTE_WARN_UNUSED_RET static inline int _fp_mul_redc1(nn_t out, nn_src_t in1, nn_src_t in2,
 26  				 fp_ctx_src_t ctx)
 27  {
 28  	return nn_mul_redc1(out, in1, in2, &(ctx->p), ctx->mpinv);
 29  }
 30  
 31  /*
 32   * Compute out = in1 * in2 mod (p) in redcified form.
 33   *
 34   * Exported version based on previous one, that sanity checks input parameters.
 35   * The function returns 0 on success, -1 on error.
 36   *
 37   * Aliasing is supported.
 38   */
 39  int fp_mul_redc1(fp_t out, fp_src_t in1, fp_src_t in2)
 40  {
 41  	int ret;
 42  
 43  	ret = fp_check_initialized(in1); EG(ret, err);
 44  	ret = fp_check_initialized(in2); EG(ret, err);
 45  	ret = fp_check_initialized(out); EG(ret, err);
 46  
 47  	MUST_HAVE((out->ctx == in1->ctx), ret, err);
 48  	MUST_HAVE((out->ctx == in2->ctx), ret, err);
 49  
 50  	ret = _fp_mul_redc1(&(out->fp_val), &(in1->fp_val), &(in2->fp_val),
 51  			    out->ctx);
 52  
 53  err:
 54  	return ret;
 55  }
 56  
 57  /*
 58   * Compute out = in * in mod (p) in redcified form.
 59   *
 60   * Aliasing is supported.
 61   */
 62  int fp_sqr_redc1(fp_t out, fp_src_t in)
 63  {
 64  	return fp_mul_redc1(out, in, in);
 65  }
 66  
 67  /*
 68   * Compute out = redcified form of in.
 69   * redcify could be done by shifting and division by p. The function returns 0
 70   * on success, -1 on error.
 71   *
 72   * Aliasing is supported.
 73   */
 74  int fp_redcify(fp_t out, fp_src_t in)
 75  {
 76  	int ret;
 77  
 78  	ret = fp_check_initialized(in); EG(ret, err);
 79  	ret = fp_check_initialized(out); EG(ret, err);
 80  
 81  	MUST_HAVE((out->ctx == in->ctx), ret, err);
 82  
 83  	ret = _fp_mul_redc1(&(out->fp_val), &(in->fp_val), &(out->ctx->r_square),
 84  			    out->ctx);
 85  
 86  err:
 87  	return ret;
 88  }
 89  
 90  /*
 91   * Compute out = unredcified form of in.
 92   * The function returns 0 on success, -1 on error.
 93   *
 94   * Aliasing is supported.
 95   */
 96  int fp_unredcify(fp_t out, fp_src_t in)
 97  {
 98  	int ret;
 99  	nn one;
100  	one.magic = WORD(0);
101  
102  	ret = fp_check_initialized(in); EG(ret, err);
103  	ret = fp_check_initialized(out); EG(ret, err);
104  	ret = nn_init(&one, 0);  EG(ret, err);
105  	ret = nn_one(&one); EG(ret, err);
106  	ret = _fp_mul_redc1(&(out->fp_val), &(in->fp_val), &one, out->ctx);
107  
108  err:
109  	nn_uninit(&one);
110  
111  	return ret;
112  }