Multi Way Feedback Encryption Standard ver-3(MWFES-3)

Recently Nath et al developed a method Multi Way Feedback Encryption Standard (MWFES) version- I and version-2. In MWFES-I, the authors used simultaneous feedback from Left Hand Side in first pass, and in the second pass, the feedback was provided from the Right Hand Side. The idea of MWFES-I is to propagate some noise from both LHS and RHS in the form forward feedback (FF) and backward feedback (BF). The feedback was added with some random key. In MWFES-I the authors have used FF in all odd passes i.e. in 1^st, 3^rd, 5-th positions and so on from LHS and the BF in the even passes such as 2^nd, 4-th, 6-th positions and so on from the RHS. In MWFES-2, the authors have introduced a generalized way to add feedback. Provision is there to apply feedback in a more flexible way. The FF and BF is applied using skip by n-characters. The skip character `n´ can be 0 to any value less than or equal to size of the plain text. In MWFES-2, the authors used both FF and BF and some random skip by `n´ number of characters for passing the feedback. The analysis of MWFES-2 results show that the results were quite satisfactory. But, both in MWFES-I and MWFES-2, the authors did not use any block concept. In the present paper (MWFES-3), the authors have divided the plain text file into several blocks. In each round of processing, the block size, the FF, the BF, the forward skip and the backward skip for each block is taken as a function of the keypad. The keypad was generated from the user entered key (seed) using the key expansion algorithm discussed later. So, after every round, these four variables (FF, BF, forward skip, backward skip) changes due to changing block size in every round. The total number of rounds in this process is also taken as a function of the user entered seed and is referred to as encryption number. After completion of a single round, the residual characters (if any) are transferred to the beginning of the encrypted text and the sam- encryption algorithm is applied again so that one complete encryption will be completed after every 2 passes. The present method gives almost unlimited scope to encrypt any message. The authors applied the present method on some standard plain texts such as 1024 ASCII `0´, 1024 ASCII `1´, 1024 ASCII `2´ and 1024 ASCII `3´. The frequency analysis and Cipher Text results show that the encrypted texts are completely random. The present MWFES-3 method thus becomes very hard to decrypt and retrieval of Plain Text from the encrypted message becomes almost impossible by any known attack method. The entire encryption and decryption processes is non-linear and hence it is almost impossible to apply any brute force or plain text attack or differential attack on this present method.