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(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(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(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(LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 105         return false;
 106 }
 107
 108 bool cipher_set_counter_key(cipher_t *cipher, void *key) {
 109         int result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, NULL);
 110         if(!result) {
 111                 logger(LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
 112                 return false;
 113         }
 114
 115         if(!cipher->counter)
 116                 cipher->counter = xmalloc_and_zero(sizeof *cipher->counter);
 117         else
 118                 cipher->counter->n = 0;
 119
 120         memcpy(cipher->counter->counter, (unsigned char *)key + cipher->cipher->key_len, cipher->cipher->block_size);
 121
 122         return true;
 123 }
 124
 125 bool cipher_counter_xor(cipher_t *cipher, const void *indata, size_t inlen, void *outdata) {
 126         if(!cipher->counter) {
 127                 logger(LOG_ERR, "Counter not initialized");
 128                 return false;
 129         }
 130
 131         const unsigned char *in = indata;
 132         unsigned char *out = outdata;
 133
 134         while(inlen--) {
 135                 // Encrypt the new counter value if we need it
 136                 if(!cipher->counter->n) {
 137                         int len;
 138                         if(!EVP_EncryptUpdate(&cipher->ctx, cipher->counter->block, &len, cipher->counter->counter, cipher->cipher->block_size)) {
 139                                 logger(LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 140                                 return false;
 141                         }
 142
 143                         // Increase the counter value
 144                         for(int i = 0; i < cipher->cipher->block_size; i++)
 145                                 if(++cipher->counter->counter[i])
 146                                         break;
 147                 }
 148
 149                 *out++ = *in++ ^ cipher->counter->counter[cipher->counter->n++];
 150
 151                 if(cipher->counter->n >= cipher->cipher->block_size)
 152                         cipher->counter->n = 0;
 153         }
 154
 155         return true;
 156 }
 157
 158
 159 bool cipher_encrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 160         if(oneshot) {
 161                 int len, pad;
 162                 if(EVP_EncryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
 163                                 && EVP_EncryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
 164                                 && EVP_EncryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
 165                         if(outlen) *outlen = len + pad;
 166                         return true;
 167                 }
 168         } else {
 169                 int len;
 170                 if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
 171                         if(outlen) *outlen = len;
 172                         return true;
 173                 }
 174         }
 175
 176         logger(LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 177         return false;
 178 }
 179
 180 bool cipher_decrypt(cipher_t *cipher, const void *indata, size_t inlen, void *outdata, size_t *outlen, bool oneshot) {
 181         if(oneshot) {
 182                 int len, pad;
 183                 if(EVP_DecryptInit_ex(&cipher->ctx, NULL, NULL, NULL, NULL)
 184                                 && EVP_DecryptUpdate(&cipher->ctx, (unsigned char *)outdata, &len, indata, inlen)
 185                                 && EVP_DecryptFinal(&cipher->ctx, (unsigned char *)outdata + len, &pad)) {
 186                         if(outlen) *outlen = len + pad;
 187                         return true;
 188                 }
 189         } else {
 190                 int len;
 191                 if(EVP_EncryptUpdate(&cipher->ctx, outdata, &len, indata, inlen)) {
 192                         if(outlen) *outlen = len;
 193                         return true;
 194                 }
 195         }
 196
 197         logger(LOG_ERR, "Error while decrypting: %s", ERR_error_string(ERR_get_error(), NULL));
 198         return false;
 199 }
 200
 201 int cipher_get_nid(const cipher_t *cipher) {
 202         return cipher->cipher ? cipher->cipher->nid : 0;
 203 }
 204
 205 bool cipher_active(const cipher_t *cipher) {
 206         return cipher->cipher && cipher->cipher->nid != 0;
 207 }