A New Symmetric Key Encryption Scheme for Binary Images

Abstract

Generally, symmetric key encryption schemes need to use a key exchange scheme for generating more secure session key between two parties. Diffie-Hellman (DH) key exchange scheme is a method to ensure the confidential construction of a shared secret key between two parties in real-time on an unsecure channel. Therefore, DH key exchange scheme is attached to existing symmetric key encryption scheme. In real implementation, normally, the shared secret key that is being established by DH key exchange scheme is used to encrypt and decrypt the subsequent communications using faster symmetric key encryption scheme. However, DH key exchange scheme is based on the difficulty to solve discrete logarithm, which is a hard mathematical problem and requires computationally heavy and complex operations. Since the Boolean operations are simple, quick, and very adaptive to be implemented to an image cryptography scheme, we propose in this paper a new symmetric key encryption scheme based on Boolean operations for binary images. The proposed scheme starts by establishing a shared secret key between two communicating parties and after that this shared secret key is then used as secret key to encrypt and decrypt the subsequent communications. The security of our scheme is based on the difficulty of solving the unsolvable non-invertible matrix problem. The performance results show that the total execution time of our scheme is better and smaller than the total execution time of the conventional scheme (DH with AES) for different sizes of data (image) files. Our scheme is fast, easily implemented and secure.