Generation of Keystream for Symmetric Cipher using U-Matrix

Symmetric-key cryptography is a classical cryptography in which both sender and receiver use the same key K to encrypt and decrypt the message. The main challenge between sender and receiver is to agree upon the secret-key which should not be revealed to public. Key management is the major issue in symmetric-key cryptosystem. To avoid these, a novel approach in generating the keystream Ks for any symmetric-key algorithms using U-matrix is proposed in this paper. The advantage of this method is generation of key K from Ks is based on some deterministic procedure which is then applied to DES algorithm and K is not necessarily remembered by both sender and receiver. Further, in each round different key is used as opposed to usage of single key in classical DES. Experimental results clearly show the security is increased when it is compared with classical DES.