Proposing A Ciphering Protocol
  This paper describes a novel bit level stream cipher based symmetric key cryptographic technique. At first, sender and receiver agree upon a symmetric key. Then the symmetric key is formed using Greatest Common Divisor (G.C.D) of sum of even or odd bit positional weightth even or odd number and a symmetric key value is derived from the symmetric by the sender. The symmetric key value is XORed with the ASCII value of the plain text character to get the cipher text character. This is repeated for the entire plain text file. The symmetric key and the entire cipher text file is sent by the sender to the receiver. From the symmetric key, the receiver calculates the symmetric key value. The symmetric key value is XORed with the cipher text character to get back the plain text character. When this process is repeated for every cipher text character, then entire plain text file is formed by the decryption process. This technique has several advantages like formation of symmetric key dynamically, more emphasis on symmetric key value rather than the symmetric key, security and equal applicability for encryption and decryption of a large number of files of almost any type or extension. 
Sarbajit Manna, Saurabh Dutta
cs.CR