+bool cipher_set_counter(cipher_t *cipher, const void *counter, size_t len) {
+ if(len > cipher->cipher->block_size - 4) {
+ logger(DEBUG_ALWAYS, LOG_ERR, "Counter too long");
+ abort();
+ }
+
+ memcpy(cipher->counter->counter + cipher->cipher->block_size - len, counter, len);
+ memset(cipher->counter->counter, 0, 4);
+ cipher->counter->n = 0;
+
+ return true;
+}
+
+bool cipher_set_counter_key(cipher_t *cipher, void *key) {
+ int result = EVP_EncryptInit_ex(&cipher->ctx, cipher->cipher, NULL, (unsigned char *)key, NULL);
+ if(!result) {
+ logger(DEBUG_ALWAYS, LOG_ERR, "Error while setting key: %s", ERR_error_string(ERR_get_error(), NULL));
+ return false;
+ }
+
+ if(!cipher->counter)
+ cipher->counter = xzalloc(sizeof *cipher->counter);
+ else
+ cipher->counter->n = 0;
+
+ memcpy(cipher->counter->counter, (unsigned char *)key + cipher->cipher->key_len, cipher->cipher->block_size);
+
+ return true;
+}
+
+bool cipher_counter_xor(cipher_t *cipher, const void *indata, size_t inlen, void *outdata) {
+ if(!cipher->counter) {
+ logger(DEBUG_ALWAYS, LOG_ERR, "Counter not initialized");
+ return false;
+ }
+
+ const unsigned char *in = indata;
+ unsigned char *out = outdata;
+
+ while(inlen--) {
+ // Encrypt the new counter value if we need it
+ if(!cipher->counter->n) {
+ int len;
+ if(!EVP_EncryptUpdate(&cipher->ctx, cipher->counter->block, &len, cipher->counter->counter, cipher->cipher->block_size)) {
+ logger(DEBUG_ALWAYS, LOG_ERR, "Error while encrypting: %s", ERR_error_string(ERR_get_error(), NULL));
+ return false;
+ }
+
+ // Increase the counter value
+ for(int i = 0; i < cipher->cipher->block_size; i++)
+ if(++cipher->counter->counter[i])
+ break;
+ }
+
+ *out++ = *in++ ^ cipher->counter->block[cipher->counter->n++];
+
+ if(cipher->counter->n >= cipher->cipher->block_size)
+ cipher->counter->n = 0;
+ }
+
+ return true;
+}
+
+