A resynchronization technique by time-synchronization for secure communication using stream cipher

Synchronous stream ciphers require perfect synchronization between the encryptor and the decryptor. However, in some applications for synchronous stream ciphers, the risk of synchronization loss (SL) cannot be eliminated completely. To reduce the risk of SL, the fixed resynchronization (FR) which makes resynchronization (resync) by inserting a sync-pattern and session-key in ciphertext at fixed timesteps is used in some cases. But there are problems associated with FR. In this paper, we propose a new resynch method to solve the problems of FR. In the proposed method, the encryptor and the decryptor make resync by using the same keystream after skipping some keystreams at fixed timesteps without inserting a sync-pattern and session-key. The proposed method is adequate for asynchronous (start/stop) DTE and is more effective than the FR in a noisy channel, because it is less dependent on channel states than the FR