Dynamic participation in a secure conference scheme for mobile communications

We propose a scheme to implement secure digital mobile communications. The scheme can both enable multiple users to hold a secure teleconference and also resolve the problem of allowing a participant to join dynamically or to quit a teleconference already in progress. Essentially, teleconference is a synchronous collaboration session in which participants at remote locations cooperate through wireless communications. Two requirements for the system are: privacy and authentication. Privacy signifies that an eavesdropper cannot intercept conversations of a conference. Authentication ensures that the service is not obtained fraudulently in order to avoid usage charge usage. We present a conference key distribution scheme for digital mobile communications, according to which users can share a common secret key to hold a secure teleconference over a public channel. The participants need not alter their secret information when a participant joins late or quits the conference early.