CRYPTOGRAPHIC APPARATUS AND METHOD FOR A DATA COMMUNICATION NETWORK

摘要

A data transmission network (12) has a plurality of computers (14) interconnected by a transmission channel (12). The computer communicates with the channel through a security device (16) which encrypts and decrypts data. The device uses a key packet distributed over the network from which a new key is derived by using the encryption process within the device. The encryption process makes use of a data sequence or "secret" peculiar to each domain so that the key generated in the domain is also peculiar to that domain. The key is changed as the encryption proceeds and upon completion of the data transmission. Each device periodically generates a new key for distribution over the network.