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         free(cipher->counter);
  69         cipher->counter = NULL;
  70 }
  71
  72 size_t cipher_keylength(const cipher_t *cipher) {
  73         return cipher->cipher->key_len + cipher->cipher->block_size;
  74 }
  75
  76 bool cipher_set_key(cipher_t *cipher, void *key, bool encrypt) {
  77         bool result;
  78
  79         if(encrypt)
  80                 result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + cipher->cipher->key_len);
  81         else
  82                 result = EVP_DecryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, (unsigned char *)key + cipher->cipher->key_len);
  83
  84         if(result)
  85                 return true;
  86
  87         logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
  88         return false;
  89 }
  90
  91 bool cipher_set_key_from_rsa(cipher_t *cipher, void *key, size_t len, bool encrypt) {
  92         bool result;
  93
  94         if(encrypt)
  95                 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);
  96         else
  97                 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);
  98
  99         if(result)
 100                 return true;
 101
 102         logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 103         return false;
 104 }
 105
 106 bool cipher_set_counter(cipher_t *cipher, const void *counter, size_t len) {
 107         if(len > cipher->cipher->block_size - 4) {
 108                 logger(DEBUG_ALWAYS, LOG_ERR, "Counter too long");
 109                 abort();
 110         }
 111
 112         memcpy(cipher->counter->counter + cipher->cipher->block_size - len, counter, len);
 113         memset(cipher->counter->counter, 0, 4);
 114         cipher->counter->n = 0;
 115
 116         return true;
 117 }
 118
 119 bool cipher_set_counter_key(cipher_t *cipher, void *key) {
 120         int result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, NULL);
 121         if(!result) {
 122                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 123                 return false;
 124         }
 125
 126         if(!cipher->counter)
 127                 cipher->counter = xmalloc_and_zero(sizeof *cipher->counter);
 128         else
 129                 cipher->counter->n = 0;
 130
 131         memcpy(cipher->counter->counter, (unsigned char *)key + cipher->cipher->key_len, cipher->cipher->block_size);
 132
 133         return true;
 134 }
 135
 136 bool cipher_counter_xor(cipher_t *cipher, const void *indata, size_t inlen, void *outdata) {
 137         if(!cipher->counter) {
 138                 logger(DEBUG_ALWAYS, LOG_ERR, "Counter not initialized");
 139                 return false;
 140         }
 141
 142         const unsigned char *in = indata;
 143         unsigned char *out = outdata;
 144
 145         while(inlen--) {
 146                 // Encrypt the new counter value if we need it
 147                 if(!cipher->counter->n) {
 148                         int len;
 149                         if(!EVP_EncryptUpdate(&cipher->ctx, cipher->counter->block, &len, cipher->counter->counter, cipher->cipher->block_size)) {
 150                                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 151                                 return false;
 152                         }
 153
 154                         // Increase the counter value
 155                         for(int i = 0; i < cipher->cipher->block_size; i++)
 156                                 if(++cipher->counter->counter[i])
 157                                         break;
 158                 }
 159
 160                 *out++ = *in++ ^ cipher->counter->counter[cipher->counter->n++];
 161
 162                 if(cipher->counter->n >= cipher->cipher->block_size)
 163                         cipher->counter->n = 0;
 164         }
 165
 166         return true;
 167 }
 168
 169
 170 bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 171         if(oneshot) {
 172                 int len, pad;
 173                 if(EVP_EncryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
 174                                 && EVP_EncryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
 175                                 && EVP_EncryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
 176                         if(outlen) *outlen = len + pad;
 177                         return true;
 178                 }
 179         } else {
 180                 int len;
 181                 if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
 182                         if(outlen) *outlen = len;
 183                         return true;
 184                 }
 185         }
 186
 187         logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 188         return false;
 189 }
 190
 191 bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 192         if(oneshot) {
 193                 int len, pad;
 194                 if(EVP_DecryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
 195                                 && EVP_DecryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
 196                                 && EVP_DecryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
 197                         if(outlen) *outlen = len + pad;
 198                         return true;
 199                 }
 200         } else {
 201                 int len;
 202                 if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
 203                         if(outlen) *outlen = len;
 204                         return true;
 205                 }
 206         }
 207
 208         logger(DEBUG_ALWAYS, LOG_ERR, "Error while decrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 209         return false;
 210 }
 211
 212 int cipher_get_nid(const cipher_t *cipher) {
 213         return cipher->cipher ? cipher->cipher->nid : 0;
 214 }
 215
 216 bool cipher_active(const cipher_t *cipher) {
 217         return cipher->cipher && cipher->cipher->nid != 0;
 218 }