Short Paper COMMENTS ON SAEEDNIA’s IMPROVED SCHEME FOR THE HILL CIPHER

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 Ht 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. Key Words: Hill cipher, known-plaintext attack, cryptosystem, one-way hash function. *Corresponding author. (Tel: 886-4-23590121 ext. 3287; Fax