Secure communication procedure for ISDN

An overview of the basic concepts of encryption is given and a key distribution problem is analyzed that arises when encryption is implemented as the basis of security services in communication networks. A secure communications procedure based on a hybrid encryption system and an adaptive version of the proposed strong three-way authentication method of the CCITT and ISO is described for solving the problem of distributing encryption and decryption keys. The most important advantage of this procedure is that the user need only to approach a trusted third party once, when joining the network. In the hybrid system, a public-key algorithm is used to distribute secrete keys over the network which are then used as the keys for a conventional system to encrypt the data messages. The integration of the secure communication procedure in ISDN to perform key distribution in association with a circuit-switched connection is also described.<>