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.h>
17  #include <libecc/fp/fp_add.h>
18  #include <libecc/fp/fp_mul.h>
19  #include <libecc/fp/fp_mul_redc1.h>
20  #include <libecc/fp/fp_montgomery.h>
21  
22  /* Compute out = in1 + in2 mod p in the Montgomery form.
23   * Inputs and outputs are in their Montgomery form.
24   * Returns 0 on success, -1 on error.
25   *
26   * Aliasing is supported.
27   */
28  int fp_add_monty(fp_t out, fp_src_t in1, fp_src_t in2)
29  {
30  	return fp_add(out, in1, in2);
31  }
32  
33  /* Compute out = in1 - in2 mod p in the Montgomery form.
34   * Inputs and outputs are in their Montgomery form.
35   * Returns 0 on success, -1 on error.
36   *
37   * Aliasing is supported.
38   */
39  int fp_sub_monty(fp_t out, fp_src_t in1, fp_src_t in2)
40  {
41  	return fp_sub(out, in1, in2);
42  }
43  
44  /* Compute out = in1 * in2 mod p in the Montgomery form.
45   * Inputs and outputs are in their Montgomery form.
46   * Returns 0 on success, -1 on error.
47   *
48   * Aliasing is supported.
49   */
50  int fp_mul_monty(fp_t out, fp_src_t in1, fp_src_t in2)
51  {
52  	return fp_mul_redc1(out, in1, in2);
53  }
54  
55  /* Compute out = in * in mod p in the Montgomery form.
56   * Inputs and outputs are in their Montgomery form.
57   * Returns 0 on success, -1 on error.
58   *
59   * Aliasing is supported.
60   */
61  int fp_sqr_monty(fp_t out, fp_src_t in)
62  {
63  	return fp_sqr_redc1(out, in);
64  }
65  
66  /*
67   * Compute out such that in1 = out * in2 mod p in the Montgomery form.
68   * Inputs and outputs are in their Montgomery form.
69   * Returns 0 on success, -1 on error. out must be initialized by the caller.
70   *
71   * Aliasing is supported.
72   */
73  int fp_div_monty(fp_t out, fp_src_t in1, fp_src_t in2)
74  {
75  	int ret, iszero;
76  
77  	ret = fp_check_initialized(in1); EG(ret, err);
78  	ret = fp_check_initialized(in2); EG(ret, err);
79  	ret = fp_check_initialized(out); EG(ret, err);
80  
81  	MUST_HAVE((out->ctx == in1->ctx), ret, err);
82  	MUST_HAVE((out->ctx == in2->ctx), ret, err);
83          FORCE_USED_VAR(iszero); /* silence warning when macro results in nothing */
84  	MUST_HAVE(!fp_iszero(in2, &iszero) && (!iszero), ret, err);
85  
86  	ret = fp_div(out, in1, in2); EG(ret, err);
87  	ret = fp_redcify(out, out);
88  
89  err:
90  	return ret;
91  }