Modified Geffe Generator Circuit for Stream Cipher

Encryption algorithms provide the securely transmitted data over insecure communication channels. In this paper a different stream cipher scheme is presented which is very simple in hardware implementation and provides relatively high level of security. Geffe generator is used for the generation of a complex key in a unique way. In this modified scheme, keystream is dependent not only on the inputs of the Geffe generator but also on the Gold Codes generated with the help of outputs of pseudo noise (PN) sequences of the two inputs of Geffe generator. Further complexity of the key is increased by introducing automatic shift of the contents of one LFSR to generate a new Gold code.