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
|
/*
Copyright (c) 2012, Matthias Schiffer <mschiffer@universe-factory.net>
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "fastd.h"
#include <crypto_secretbox_xsalsa20poly1305.h>
#define NONCEBYTES 7
struct _fastd_method_session_state {
struct timespec valid_till;
struct timespec refresh_after;
uint8_t key[crypto_secretbox_xsalsa20poly1305_KEYBYTES];
uint8_t send_nonce[NONCEBYTES];
uint8_t receive_nonce[NONCEBYTES];
};
static inline void increment_nonce(uint8_t nonce[NONCEBYTES]) {
nonce[0] += 2;
if (nonce[0] == 0 || nonce[0] == 1) {
int i;
for (i = 1; i < NONCEBYTES; i++) {
nonce[i]++;
if (nonce[i] != 0)
break;
}
}
}
static inline bool is_nonce_valid(const uint8_t nonce[NONCEBYTES], const uint8_t old_nonce[NONCEBYTES]) {
if ((nonce[0] & 1) != (old_nonce[0] & 1))
return false;
int i;
for (i = NONCEBYTES-1; i >= 0; i--) {
if (nonce[i] > old_nonce[i])
return true;
if (nonce[i] < old_nonce[i])
return false;
}
return false;
}
static size_t method_max_packet_size(fastd_context *ctx) {
return (fastd_max_packet_size(ctx) + NONCEBYTES + crypto_secretbox_xsalsa20poly1305_ZEROBYTES - crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES);
}
static size_t method_min_encrypt_head_space(fastd_context *ctx) {
return crypto_secretbox_xsalsa20poly1305_ZEROBYTES;
}
static size_t method_min_decrypt_head_space(fastd_context *ctx) {
return (crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES - NONCEBYTES);
}
static fastd_method_session_state* method_session_init(fastd_context *ctx, uint8_t *secret, size_t length, bool initiator) {
int i;
if (length < crypto_secretbox_xsalsa20poly1305_KEYBYTES)
exit_bug(ctx, "xsalsa20-poly1305: tried to init with short secret");
fastd_method_session_state *session = malloc(sizeof(fastd_method_session_state));
session->valid_till = ctx->now;
session->valid_till.tv_sec += ctx->conf->key_valid;
session->refresh_after = ctx->now;
session->refresh_after.tv_sec += ctx->conf->key_refresh;
memcpy(session->key, secret, crypto_secretbox_xsalsa20poly1305_KEYBYTES);
session->send_nonce[0] = initiator ? 3 : 2;
session->receive_nonce[0] = initiator ? 0 : 1;
for (i = 1; i < NONCEBYTES; i++) {
session->send_nonce[i] = 0;
session->receive_nonce[i] = 0;
}
return session;
}
static bool method_session_is_valid(fastd_context *ctx, fastd_method_session_state *session) {
return (session && timespec_after(&session->valid_till, &ctx->now));
}
static bool method_session_is_initiator(fastd_context *ctx, fastd_method_session_state *session) {
return (session->send_nonce[0] & 1);
}
static bool method_session_want_refresh(fastd_context *ctx, fastd_method_session_state *session) {
return (method_session_is_initiator(ctx, session) && timespec_after(&ctx->now, &session->refresh_after));
}
static void method_session_free(fastd_context *ctx, fastd_method_session_state *session) {
if(session) {
memset(session, 0, sizeof(fastd_method_session_state));
free(session);
}
}
static bool method_encrypt(fastd_context *ctx, fastd_method_session_state *session, fastd_buffer *out, fastd_buffer in) {
fastd_buffer_pull_head(&in, crypto_secretbox_xsalsa20poly1305_ZEROBYTES);
memset(in.data, 0, crypto_secretbox_xsalsa20poly1305_ZEROBYTES);
*out = fastd_buffer_alloc(in.len, 0, 0);
uint8_t nonce[crypto_secretbox_xsalsa20poly1305_NONCEBYTES];
memcpy(nonce, session->send_nonce, NONCEBYTES);
memset(nonce+NONCEBYTES, 0, crypto_secretbox_xsalsa20poly1305_NONCEBYTES-NONCEBYTES);
crypto_secretbox_xsalsa20poly1305(out->data, in.data, in.len, nonce, session->key);
fastd_buffer_free(in);
fastd_buffer_push_head(out, crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES-NONCEBYTES);
memcpy(out->data, session->send_nonce, NONCEBYTES);
increment_nonce(session->send_nonce);
return true;
}
static bool method_decrypt(fastd_context *ctx, fastd_method_session_state *session, fastd_buffer *out, fastd_buffer in) {
if (in.len < NONCEBYTES)
return false;
if (!method_session_is_valid(ctx, session))
return false;
uint8_t nonce[crypto_secretbox_xsalsa20poly1305_NONCEBYTES];
memcpy(nonce, in.data, NONCEBYTES);
memset(nonce+NONCEBYTES, 0, crypto_secretbox_xsalsa20poly1305_NONCEBYTES-NONCEBYTES);
if (!is_nonce_valid(nonce, session->receive_nonce))
return false;
fastd_buffer_pull_head(&in, crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES-NONCEBYTES);
memset(in.data, 0, crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES);
*out = fastd_buffer_alloc(in.len, 0, 0);
if (crypto_secretbox_xsalsa20poly1305_open(out->data, in.data, in.len, nonce, session->key) != 0) {
fastd_buffer_free(*out);
/* restore input buffer */
fastd_buffer_push_head(&in, crypto_secretbox_xsalsa20poly1305_BOXZEROBYTES-NONCEBYTES);
memcpy(in.data, nonce, NONCEBYTES);
return false;
}
fastd_buffer_free(in);
fastd_buffer_push_head(out, crypto_secretbox_xsalsa20poly1305_ZEROBYTES);
memcpy(session->receive_nonce, nonce, NONCEBYTES);
return true;
}
const fastd_method fastd_method_xsalsa20_poly1305 = {
.name = "xsalsa20-poly1305",
.max_packet_size = method_max_packet_size,
.min_encrypt_head_space = method_min_encrypt_head_space,
.min_decrypt_head_space = method_min_decrypt_head_space,
.session_init = method_session_init,
.session_is_valid = method_session_is_valid,
.session_is_initiator = method_session_is_initiator,
.session_want_refresh = method_session_want_refresh,
.session_free = method_session_free,
.encrypt = method_encrypt,
.decrypt = method_decrypt,
};
|
