Comments on Saeednia's improved scheme for the hill cipher

Abstract

In 2000, Saeednia proposed a new scheme to make the Hill cipher secure. The author makes use of permutations of columns and rows of a matrix to get a different key for encrypting each message. This paper shows that the cipher key H-t can be obtained by parameter u. Besides, the Saeednia's scheme costs a lot of time in matrix computation. To overcome the drawbacks of Saeednia's scheme, a more secure cryptosystem with a one-way hash function is proposed.