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 */
_fp_mul_redc1(nn_t out,nn_src_t in1,nn_src_t in2,fp_ctx_src_t ctx)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 */
fp_mul_redc1(fp_t out,fp_src_t in1,fp_src_t in2)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 */
fp_sqr_redc1(fp_t out,fp_src_t in)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 */
fp_redcify(fp_t out,fp_src_t in)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 */
fp_unredcify(fp_t out,fp_src_t in)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 }
113