Bit and Byte Level Generalized Modified Vernam Cipher Method with Feedback

Abstract

In the present paper the authors have introduced a new symmetric key cryptographic method where they have clubbed both bit level and byte level generalized modified vernam cipher method with feedback. Nath et al already developed methods bit level encryption standard(BLES) Ver-I and Ver-II where they have used extensive bit level permutation, bit exchange, bit xor and bit shift encryption method. Nath et al also developed a method bit level generalised vernam cipher method. In the present study the authors have used both bit level generalized vernam cipher method and after that byte level vernam cipher method using feedback. Due to introduction of feedback in both bit level as well as byte level vernam cipher method the common attacks such as differential attack or known plain text attack is not applicable in the present method. In the present paper the authors have used random key generator to construct the keypad for vernam cipher method. The authors have introduced a special bit manipulation method so the encryption algorithm will work even for all characters with ASCII Code 0 or all characters with ASCII Code 255. The most of the standard algorithm will fail to encrypt a file where all characters are ASCII ‘0’ or all characters with ASCII ‘255’ where as the present method will be able to encrypt a file where all characters are ASCII ‘0’ or all characters are ASCII ‘255’. The present method will be effective for encrypting short message, password, confidential key etc. General Terms encryption, bit-level