tinc-vpn.org Git - tinc/blob - 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 }