User identification and cipher synchronization in speech information hiding

User identification must be done in speech information hiding. To shorten the time of building link and exchanging protocol, this paper presents a technology for fast cross-identification. To enhance the security of communication, encryption should be done before hiding information. After encryption, secure info is hidden in the host info which has been recorded. Since speech communications are on the full-duplex synchronization link and have burst of communications, so we use the same encryption and decryption algorithms on both sides to avoid increasing operation spending which is caused when using different encryption and decryption algorithms. A strict synchronization algorithm is requested; so the cycle buffer synchronization algorithm is presented.