LFL-A New Stream Cipher for Secure Communications

Stream ciphers are widely used in wireless communications to transfer the data securely through insecure channel. This paper presents a new design of stream cipher(LFL) which consists of two LFSRs and one FCSR with combiner, which is bit oriented. LFL has two stages, Initiliazation and KSG(Key Stream Generation). During the Intiliazation stage, key and IV are initialized or loaded into the registers and the system is iterated 70 times by discarding the output. In KSG stage, PRGA(Pseudorandom Generation algorithm) is performed from 71st iteration onwards, it produces a bit of output with every clock pulse. These bits are XORed with the plaintext to produce ciphertext. Key stream of LFL passes almost all statistical tests of the NIST test suite. Security of the cipher against different attacks are discussed. Due to the key size and use of combination of LFSRs and FCSR our design is more secure.