1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
|
/* rsa.h
*
* The RSA publickey algorithm.
*/
/* nettle, low-level cryptographics library
*
* Copyright (C) 2001, 2002 Niels Möller
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
* MA 02111-1307, USA.
*/
#ifndef NETTLE_RSA_H_INCLUDED
#define NETTLE_RSA_H_INCLUDED
#include <inttypes.h>
#include <gmp.h>
#include "md5.h"
#include "sha.h"
/* For nettle_random_func */
#include "nettle-meta.h"
/* For PKCS#1 to make sense, the size of the modulo, in octets, must
* be at least 11 + the length of the DER-encoded Digest Info.
*
* And a DigestInfo is 34 octets for md5, and 35 octets for sha1. 46
* octets is 368 bits, and as the upper 7 bits may be zero, the
* smallest useful size of n is 361 bits. */
#define RSA_MINIMUM_N_OCTETS 46
#define RSA_MINIMUM_N_BITS 361
struct rsa_public_key
{
/* Size of the modulo, in octets. This is also the size of all
* signatures that are created or verified with this key. */
unsigned size;
/* Modulo */
mpz_t n;
/* Public exponent */
mpz_t e;
};
struct rsa_private_key
{
unsigned size;
/* d is filled in by the key generation function; otherwise it's
* completely unused. */
mpz_t d;
/* The two factors */
mpz_t p; mpz_t q;
/* d % (p-1), i.e. a e = 1 (mod (p-1)) */
mpz_t a;
/* d % (q-1), i.e. b e = 1 (mod (q-1)) */
mpz_t b;
/* modular inverse of q , i.e. c q = 1 (mod p) */
mpz_t c;
};
/* Signing a message works as follows:
*
* Store the private key in a rsa_private_key struct.
*
* Call rsa_prepare_private_key. This initializes the size attribute
* to the length of a signature.
*
* Initialize a hashing context, by callling
* md5_init
*
* Hash the message by calling
* md5_update
*
* Create the signature by calling
* rsa_md5_sign
*
* The signature is represented as a mpz_t bignum. This call also
* resets the hashing context.
*
* When done with the key and signature, don't forget to call
* mpz_clear.
*/
/* FIXME: For consistency, these functions ought to be renamed to
* rsa_public_key_init, rsa_public_key_clear, rsa_private_key_init,
* rsa_private_key_clear. Perhaps the prepare functions should be
* renamed too. Do this for nettle-2.0? */
/* Calls mpz_init to initialize bignum storage. */
void
rsa_init_public_key(struct rsa_public_key *key);
/* Calls mpz_clear to deallocate bignum storage. */
void
rsa_clear_public_key(struct rsa_public_key *key);
int
rsa_prepare_public_key(struct rsa_public_key *key);
/* Calls mpz_init to initialize bignum storage. */
void
rsa_init_private_key(struct rsa_private_key *key);
/* Calls mpz_clear to deallocate bignum storage. */
void
rsa_clear_private_key(struct rsa_private_key *key);
int
rsa_prepare_private_key(struct rsa_private_key *key);
/* PKCS#1 style signatures */
void
rsa_md5_sign(const struct rsa_private_key *key,
struct md5_ctx *hash,
mpz_t signature);
int
rsa_md5_verify(const struct rsa_public_key *key,
struct md5_ctx *hash,
const mpz_t signature);
void
rsa_sha1_sign(const struct rsa_private_key *key,
struct sha1_ctx *hash,
mpz_t signature);
int
rsa_sha1_verify(const struct rsa_public_key *key,
struct sha1_ctx *hash,
const mpz_t signature);
/* RSA encryption, using PKCS#1 */
/* FIXME: These functions uses the v1.5 padding. What should the v2
* (OAEP) functions be called? */
/* Returns 1 on success, 0 on failure, which happens if the
* message is too long for the key. */
int
rsa_encrypt(const struct rsa_public_key *key,
/* For padding */
void *random_ctx, nettle_random_func random,
unsigned length, const uint8_t *cleartext,
mpz_t cipher);
/* Message must point to a buffer of size *LENGTH. KEY->size is enough
* for all valid messages. On success, *LENGTH is updated to reflect
* the actual length of the message. Returns 1 on success, 0 on
* failure, which happens if decryption failed or if the message
* didn't fit. */
int
rsa_decrypt(const struct rsa_private_key *key,
unsigned *length, uint8_t *cleartext,
const mpz_t ciphertext);
/* Compute x, the e:th root of m. Calling it with x == m is allowed. */
void
rsa_compute_root(const struct rsa_private_key *key,
mpz_t x, const mpz_t m);
/* Key generation */
/* Note that the key structs must be initialized first. */
int
rsa_generate_keypair(struct rsa_public_key *pub,
struct rsa_private_key *key,
void *random_ctx, nettle_random_func random,
void *progress_ctx, nettle_progress_func progress,
/* Desired size of modulo, in bits */
unsigned n_size,
/* Desired size of public exponent, in bits. If
* zero, the passed in value pub->e is used. */
unsigned e_size);
#define RSA_SIGN(key, algorithm, ctx, length, data, signature) ( \
algorithm##_update(ctx, length, data), \
rsa_##algorithm##_sign(key, ctx, signature) \
)
#define RSA_VERIFY(key, algorithm, ctx, length, data, signature) ( \
algorithm##_update(ctx, length, data), \
rsa_##algorithm##_verify(key, ctx, signature) \
)
/* Keys in sexp form. */
struct nettle_buffer;
/* Generates a public-key expression if PRIV is NULL .*/
int
rsa_keypair_to_sexp(struct nettle_buffer *buffer,
const struct rsa_public_key *pub,
const struct rsa_private_key *priv);
struct sexp_iterator;
int
rsa_keypair_from_sexp_alist(struct rsa_public_key *pub,
struct rsa_private_key *priv,
unsigned limit,
struct sexp_iterator *i);
/* If PRIV is NULL, expect a public-key expression. If PUB is NULL,
* expect a private key expression and ignore the parts not needed for
* the public key. */
/* Keys must be initialized before calling this function, as usual. */
int
rsa_keypair_from_sexp(struct rsa_public_key *pub,
struct rsa_private_key *priv,
unsigned limit,
unsigned length, const uint8_t *expr);
/* OpenPGP format. Experimental interface, subject to change. */
int
rsa_keypair_to_openpgp(struct nettle_buffer *buffer,
const struct rsa_public_key *pub,
const struct rsa_private_key *priv,
/* A single user id. NUL-terminated utf8. */
const char userid);
#endif /* NETTLE_RSA_H_INCLUDED */
|
