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[tinc] / src / openssl / cipher.c
1 /*
2     cipher.c -- Symmetric block cipher handling
3     Copyright (C) 2007 Guus Sliepen <guus@tinc-vpn.org>
4
5     This program is free software; you can redistribute it and/or modify
6     it under the terms of the GNU General Public License as published by
7     the Free Software Foundation; either version 2 of the License, or
8     (at your option) any later version.
9
10     This program is distributed in the hope that it will be useful,
11     but WITHOUT ANY WARRANTY; without even the implied warranty of
12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13     GNU General Public License for more details.
14
15     You should have received a copy of the GNU General Public License along
16     with this program; if not, write to the Free Software Foundation, Inc.,
17     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #include "system.h"
21
22 #include <openssl/rand.h>
23 #include <openssl/err.h>
24
25 #include "cipher.h"
26 #include "logger.h"
27 #include "xalloc.h"
28
29 typedef struct cipher_counter {
30         unsigned char counter[EVP_MAX_IV_LENGTH];
31         unsigned char block[EVP_MAX_IV_LENGTH];
32         int n;
33 } cipher_counter_t;
34
35 static bool cipher_open(cipher_t *cipher) {
36         EVP_CIPHER_CTX_init(&cipher->ctx);
37
38         return true;
39 }
40
41 bool cipher_open_by_name(cipher_t *cipher, const char *name) {
42         cipher->cipher = EVP_get_cipherbyname(name);
43
44         if(cipher->cipher)
45                 return cipher_open(cipher);
46
47         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher name '%s'!", name);
48         return false;
49 }
50
51 bool cipher_open_by_nid(cipher_t *cipher, int nid) {
52         cipher->cipher = EVP_get_cipherbynid(nid);
53
54         if(cipher->cipher)
55                 return cipher_open(cipher);
56
57         logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher nid %d!", nid);
58         return false;
59 }
60
61 bool cipher_open_blowfish_ofb(cipher_t *cipher) {
62         cipher->cipher = EVP_bf_ofb();
63         return cipher_open(cipher);
64 }
65
66 void cipher_close(cipher_t *cipher) {
67         EVP_CIPHER_CTX_cleanup(&cipher->ctx);
68         if(cipher->counter) {
69                 free(cipher->counter);
70                 cipher->counter = 0;
71         }
72 }
73
74 size_t cipher_keylength(const cipher_t *cipher) {
75         return cipher->cipher->key_len + cipher->cipher->block_size;
76 }
77
78 bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
79         bool result;
80
81         if(encrypt)
82                 result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + cipher->cipher->key_len);
83         else
84                 result = EVP_DecryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + cipher->cipher->key_len);
85
86         if(result)
87                 return true;
88
89         logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
90         return false;
91 }
92
93 bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encrypt) {
94         bool result;
95
96         if(encrypt)
97                 result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key + len - cipher->cipher->key_len, (unsigned char *)key + len - cipher->cipher->iv_len - cipher->cipher->key_len);
98         else
99                 result = EVP_DecryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key + len - cipher->cipher->key_len, (unsigned char *)key + len - cipher->cipher->iv_len - cipher->cipher->key_len);
100
101         if(result)
102                 return true;
103
104         logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
105         return false;
106 }
107
108 bool cipher_set_counter(cipher_t *cipher, const void *counter, size_t len) {
109         if(len > cipher->cipher->block_size - 4) {
110                 logger(DEBUG_ALWAYS, LOG_ERR, "Counter too long");
111                 abort();
112         }
113
114         memcpy(cipher->counter->counter + cipher->cipher->block_size - len, counter, len);
115         memset(cipher->counter->counter, 0, 4);
116         cipher->counter->n = 0;
117
118         return true;
119 }
120
121 bool cipher_set_counter_key(cipher_t *cipher, void *key) {
122         int result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, NULL);
123         if(!result) {
124                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
125                 return false;
126         }
127
128         if(!cipher->counter)
129                 cipher->counter = xmalloc_and_zero(sizeof *cipher->counter);
130         else
131                 cipher->counter->n = 0;
132
133         memcpy(cipher->counter->counter, (unsigned char *)key + cipher->cipher->key_len, cipher->cipher->block_size);
134
135         return true;
136 }
137
138 bool cipher_counter_xor(cipher_t *cipher, const void *indata, size_t inlen, void *outdata) {
139         if(!cipher->counter) {
140                 logger(DEBUG_ALWAYS, LOG_ERR, "Counter not initialized");
141                 return false;
142         }
143
144         const unsigned char *in = indata;
145         unsigned char *out = outdata;
146
147         while(inlen--) {
148                 // Encrypt the new counter value if we need it 
149                 if(!cipher->counter->n) {
150                         int len;
151                         if(!EVP_EncryptUpdate(&cipher->ctx, cipher->counter->block, &len, cipher->counter->counter, cipher->cipher->block_size)) {
152                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
153                                 return false;
154                         }
155
156                         // Increase the counter value
157                         for(int i = 0; i < cipher->cipher->block_size; i++)
158                                 if(++cipher->counter->counter[i])
159                                         break;
160                 }
161
162                 *out++ = *in++ ^ cipher->counter->counter[cipher->counter->n++];
163
164                 if(cipher->counter->n >= cipher->cipher->block_size)
165                         cipher->counter->n = 0;
166         }
167
168         return true;
169 }
170
171
172 bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
173         if(oneshot) {
174                 int len, pad;
175                 if(EVP_EncryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
176                                 && EVP_EncryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
177                                 && EVP_EncryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
178                         if(outlen) *outlen = len + pad;
179                         return true;
180                 }
181         } else {
182                 int len;
183                 if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
184                         if(outlen) *outlen = len;
185                         return true;
186                 }
187         }
188
189         logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
190         return false;
191 }
192
193 bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
194         if(oneshot) {
195                 int len, pad;
196                 if(EVP_DecryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
197                                 && EVP_DecryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
198                                 && EVP_DecryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
199                         if(outlen) *outlen = len + pad;
200                         return true;
201                 }
202         } else {
203                 int len;
204                 if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
205                         if(outlen) *outlen = len;
206                         return true;
207                 }
208         }
209
210         logger(DEBUG_ALWAYS, LOG_ERR, "Error while decrypting: %s", ERR_error_string(ERR_get_error(), NULL));
211         return false;
212 }
213
214 int cipher_get_nid(const cipher_t *cipher) {
215         return cipher->cipher ? cipher->cipher->nid : 0;
216 }
217
218 bool cipher_active(const cipher_t *cipher) {
219         return cipher->cipher && cipher->cipher->nid != 0;
220 }