A Rotation Session Key-Based Transposition Cryptosystem Scheme Applied to Mobile Text Chatting

A block cipher uses classical substitution whereas a new transposition cryptosystem scheme with matrix rotation for enhanced protection over Internet text chatting. The transposition scheme with matrix rotation proposed is entirely dependent on key and induces security by having substitution and transposition both dependent on secret key and session key. The scheme is design to be iterative and it can also be extended for many rounds. The security strength is safer compared to other approaches under the frequency analysis. The scheme minimizes weaknesses including the possibilities of related key attacks due to weak key scheduling. An implementation of the cryptosystem scheme is done and working is explained via examples.