  In poly alphabetic substitution the plain texts letters are enciphered
differently according to their position. The name poly alphabetic 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 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.
