www.tinc-vpn.org Git - tinc/blob - src/openssl/cipher.c

   1 /*
   2     cipher.c -- Symmetric block cipher handling
   3     Copyright (C) 2007-2013 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 #include <openssl/evp.h>
  25
  26 #include "../cipher.h"
  27 #include "../logger.h"
  28 #include "../xalloc.h"
  29
  30 struct cipher {
  31         EVP_CIPHER_CTX ctx;
  32         const EVP_CIPHER *cipher;
  33         struct cipher_counter *counter;
  34 };
  35
  36 typedef struct cipher_counter {
  37         unsigned char counter[CIPHER_MAX_IV_SIZE];
  38         unsigned char block[CIPHER_MAX_IV_SIZE];
  39         int n;
  40 } cipher_counter_t;
  41
  42 static cipher_t *cipher_open(const EVP_CIPHER *evp_cipher) {
  43         cipher_t *cipher = xzalloc(sizeof *cipher);
  44         cipher->cipher = evp_cipher;
  45         EVP_CIPHER_CTX_init(&cipher->ctx);
  46
  47         return cipher;
  48 }
  49
  50 cipher_t *cipher_open_by_name(const char *name) {
  51         const EVP_CIPHER *evp_cipher = EVP_get_cipherbyname(name);
  52         if(!evp_cipher) {
  53                 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher name '%s'!", name);
  54                 return NULL;
  55         }
  56
  57         return cipher_open(evp_cipher);
  58 }
  59
  60 cipher_t *cipher_open_by_nid(int nid) {
  61         const EVP_CIPHER *evp_cipher = EVP_get_cipherbynid(nid);
  62         if(!evp_cipher) {
  63                 logger(DEBUG_ALWAYS, LOG_ERR, "Unknown cipher nid %d!", nid);
  64                 return NULL;
  65         }
  66
  67         return cipher_open(evp_cipher);
  68 }
  69
  70 cipher_t *cipher_open_blowfish_ofb(void) {
  71         return cipher_open(EVP_bf_ofb());
  72 }
  73
  74 void cipher_close(cipher_t *cipher) {
  75         if(!cipher)
  76                 return;
  77
  78         EVP_CIPHER_CTX_cleanup(&cipher->ctx);
  79         free(cipher->counter);
  80         free(cipher);
  81 }
  82
  83 size_t cipher_keylength(const cipher_t *cipher) {
  84         if(!cipher || !cipher->cipher)
  85                 return 0;
  86
  87         return cipher->cipher->key_len + cipher->cipher->block_size;
  88 }
  89
  90 bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
  91         bool result;
  92
  93         if(encrypt)
  94                 result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + cipher->cipher->key_len);
  95         else
  96                 result = EVP_DecryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + cipher->cipher->key_len);
  97
  98         if(result)
  99                 return true;
 100
 101         logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 102         return false;
 103 }
 104
 105 bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encrypt) {
 106         bool result;
 107
 108         if(encrypt)
 109                 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);
 110         else
 111                 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);
 112
 113         if(result)
 114                 return true;
 115
 116         logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 117         return false;
 118 }
 119
 120 bool cipher_set_counter(cipher_t *cipher, const void *counter, size_t len) {
 121         if(len > cipher->cipher->block_size - 4) {
 122                 logger(DEBUG_ALWAYS, LOG_ERR, "Counter too long");
 123                 abort();
 124         }
 125
 126         memcpy(cipher->counter->counter + cipher->cipher->block_size - len, counter, len);
 127         memset(cipher->counter->counter, 0, 4);
 128         cipher->counter->n = 0;
 129
 130         return true;
 131 }
 132
 133 bool cipher_set_counter_key(cipher_t *cipher, void *key) {
 134         int result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, NULL);
 135         if(!result) {
 136                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 137                 return false;
 138         }
 139
 140         if(!cipher->counter)
 141                 cipher->counter = xzalloc(sizeof *cipher->counter);
 142         else
 143                 cipher->counter->n = 0;
 144
 145         memcpy(cipher->counter->counter, (unsigned char *)key + cipher->cipher->key_len, cipher->cipher->block_size);
 146
 147         return true;
 148 }
 149
 150 bool cipher_counter_xor(cipher_t *cipher, const void *indata, size_t inlen, void *outdata) {
 151         if(!cipher->counter) {
 152                 logger(DEBUG_ALWAYS, LOG_ERR, "Counter not initialized");
 153                 return false;
 154         }
 155
 156         const unsigned char *in = indata;
 157         unsigned char *out = outdata;
 158
 159         while(inlen--) {
 160                 // Encrypt the new counter value if we need it
 161                 if(!cipher->counter->n) {
 162                         int len;
 163                         if(!EVP_EncryptUpdate(&cipher->ctx, cipher->counter->block, &len, cipher->counter->counter, cipher->cipher->block_size)) {
 164                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 165                                 return false;
 166                         }
 167
 168                         // Increase the counter value
 169                         for(int i = 0; i < cipher->cipher->block_size; i++)
 170                                 if(++cipher->counter->counter[i])
 171                                         break;
 172                 }
 173
 174                 *out++ = *in++ ^ cipher->counter->block[cipher->counter->n++];
 175
 176                 if(cipher->counter->n >= cipher->cipher->block_size)
 177                         cipher->counter->n = 0;
 178         }
 179
 180         return true;
 181 }
 182
 183
 184 bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 185         if(oneshot) {
 186                 int len, pad;
 187                 if(EVP_EncryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
 188                                 && EVP_EncryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
 189                                 && EVP_EncryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
 190                         if(outlen) *outlen = len + pad;
 191                         return true;
 192                 }
 193         } else {
 194                 int len;
 195                 if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
 196                         if(outlen) *outlen = len;
 197                         return true;
 198                 }
 199         }
 200
 201         logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 202         return false;
 203 }
 204
 205 bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 206         if(oneshot) {
 207                 int len, pad;
 208                 if(EVP_DecryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
 209                                 && EVP_DecryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
 210                                 && EVP_DecryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
 211                         if(outlen) *outlen = len + pad;
 212                         return true;
 213                 }
 214         } else {
 215                 int len;
 216                 if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
 217                         if(outlen) *outlen = len;
 218                         return true;
 219                 }
 220         }
 221
 222         logger(DEBUG_ALWAYS, LOG_ERR, "Error while decrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 223         return false;
 224 }
 225
 226 int cipher_get_nid(const cipher_t *cipher) {
 227         if(!cipher || !cipher->cipher)
 228                 return 0;
 229
 230         return cipher->cipher->nid;
 231 }
 232
 233 bool cipher_active(const cipher_t *cipher) {
 234         return cipher && cipher->cipher && cipher->cipher->nid != 0;
 235 }