nettle  3.7.3
About: Nettle is a low-level cryptographic library.
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rsa.c
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1 /* rsa.c
2 
3  The RSA publickey algorithm.
4 
5  Copyright (C) 2001 Niels Möller
6 
7  This file is part of GNU Nettle.
8 
9  GNU Nettle is free software: you can redistribute it and/or
10  modify it under the terms of either:
11 
12  * the GNU Lesser General Public License as published by the Free
13  Software Foundation; either version 3 of the License, or (at your
14  option) any later version.
15 
16  or
17 
18  * the GNU General Public License as published by the Free
19  Software Foundation; either version 2 of the License, or (at your
20  option) any later version.
21 
22  or both in parallel, as here.
23 
24  GNU Nettle is distributed in the hope that it will be useful,
25  but WITHOUT ANY WARRANTY; without even the implied warranty of
26  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
27  General Public License for more details.
28 
29  You should have received copies of the GNU General Public License and
30  the GNU Lesser General Public License along with this program. If
31  not, see http://www.gnu.org/licenses/.
32 */
33 
34 #if HAVE_CONFIG_H
35 # include "config.h"
36 #endif
37 
38 #include "rsa.h"
39 #include "rsa-internal.h"
40 
41 #include "bignum.h"
42 
43 void
45 {
46  mpz_init(key->n);
47  mpz_init(key->e);
48 
49  /* Not really necessary, but it seems cleaner to initialize all the
50  * storage. */
51  key->size = 0;
52 }
53 
54 void
56 {
57  mpz_clear(key->n);
58  mpz_clear(key->e);
59 }
60 
61 /* Computes the size, in octets, of a the modulo. Returns 0 if the
62  * modulo is too small to be useful, or otherwise appears invalid. */
63 size_t
65 {
66  /* Round upwards */
67  size_t size;
68 
69  /* Even moduli are invalid, and not supported by mpz_powm_sec. */
70  if (mpz_even_p (n))
71  return 0;
72 
73  size = (mpz_sizeinbase(n, 2) + 7) / 8;
74 
75  if (size < RSA_MINIMUM_N_OCTETS)
76  return 0;
77 
78  return size;
79 }
80 
81 int
83 {
84  key->size = _rsa_check_size(key->n);
85 
86  return (key->size > 0);
87 }
size_t mpz_sizeinbase(const mpz_t u, int base)
Definition: mini-gmp.c:4167
void mpz_init(mpz_t r)
Definition: mini-gmp.c:1410
void mpz_clear(mpz_t r)
Definition: mini-gmp.c:1435
__mpz_struct mpz_t[1]
Definition: mini-gmp.h:77
#define mpz_even_p(z)
Definition: mini-gmp.h:131
#define _rsa_check_size
Definition: rsa-internal.h:41
#define rsa_public_key_prepare
Definition: rsa.h:51
#define rsa_public_key_clear
Definition: rsa.h:50
#define RSA_MINIMUM_N_OCTETS
Definition: rsa.h:111
#define rsa_public_key_init
Definition: rsa.h:49
size_t size
Definition: rsa.h:118
mpz_t e
Definition: rsa.h:124
mpz_t n
Definition: rsa.h:121