Variable Size Block Encryption and Generate the Key of Variable Length
The weak point of the block Encryption is the plain text or encryption key could be easily exposed . This is because the encryption schemes have been designed for the fixed size encryption key. But by this method, we generate the Key of the variable length according the required length , of the user that encrypt the message and want to safe their information.
Another weak point of the existing block encryption algorithm is that it has a fixed number of encryption rounds.In this method the number of the encryption round are not fixed but it is vary according to the ASCII values of the Plain Text in order to produce the Cipher Text during the Encryption method. By using the that key we can decrypt the Cipher Text into the Plain Text during the Decryption method. This method provide Polyalphabetic Substitution . 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. The variable key size, variable number of rounds of Encryption and Polyalphabetic Substitution makes the crypt analyst too hard to analyzing the cipher text. This method generates the random Cipher text for the same Plain Text by varying the Key length.