Date Added: Dec 2012
In the present paper, a block cipher is presented which deals with a dynamic symmetric key cryptographic method using substitution and transposition technique. In this paper a dynamic secret key is generated using Linear Congruential Generator (LCG). The striking feature of the present work is creation of a new secret key for every pair of encryption and decryption operation, thus secret key is a dynamic key. After encryption and decryption operation the dynamic key is discarded. The proposed cryptography method is a process consisting of two rounds of encryption and two rounds of decryption. The key generation algorithm uses SHA-1 hashing scheme to produce key of size 196 bits.