The Science and Information (SAI) Organization
In cryptography stream ciphers used to encrypt plain text data bits one by one. The security of stream ciphers depend upon randomness of key stream, good linear span and low probability of finding the initial states of pseudorandom generators. In this paper, the authors propose a new stream cipher model use Feed back with Carry Shift Registers (FCSRs) as building blocks which are considered as a source of long pseudorandom generator. Proposed model is the combined structure of alternating step generator and self shrinking generators which are commonly used stream ciphers generators.