IJASCSE Vol 1, Issue 3, 2012

In polyalphabetic substitution the plain text’s letters are enciphered differently according to their position. The name polyalphabetic suggests that there are more than one key so we have used two keys combination instead of just one, in order to produce the cipher text. We can also use three or more keys to make the enciphering process more complicated. In this paper have produced ASCII Codes of the plain text and then we have reversed it said reverse ASCII Codes and then we have generated two keys named K1 and K2. K1 is generated by addition of reverse ASCII Codes and K2 is generated by addition of ASCII Codes. Then these K1 and K2 Keys are alternatively applied on Reverse ASCII codes in order to produce cipher text. On the Destination hand Deciphering is used to produce the plain text again. Our technique generates random cipher text for the same plain text and this is the major advantage of our technique.