Information security is an important issue. Today’s encryption technologies can be traced back to the earliest ciphers, and have grown as a result of evolution. The first ciphers were cracked, so new, stronger ciphers emerged. Code breakers set to work on these and eventually found flaws, forcing cryptographers to invent better ciphers and so on. Hill Cipher is one of the most famous symmetric cryptosystem that can be used to protect information from unauthorized access. Hill cipher is a polygraph substitution cipher based on linear algebra. it was the first polygraph cipher which was practical to operate on more than three symbols at once, Hill Cipher has many advantages in data encryption. First, it is resistant to the frequency letter analysis. It's also very simple since it uses matrix multiplication. Finally, it has high speed and high throughput. However, noninvertible key matrix over is the main disadvantage of Hill Cipher, because few of the matrices have inverses over . This means that the encrypted text can't be decrypted. Moreover, Hill cipher algorithm cannot encrypt images that contain large areas of a single color. Thus, it does not hide all features of the image which reveals patterns in the plaintext. Moreover, it can be easily broken with a known plaintext attack revealing weak security. The objective of this paper is to encrypt an image using a technique different from the conventional one. In this paper, a novel encryption technique has been proposed which we name H-S-X (Hill-Shift-XOR) encryption. The scheme is relatively slow but quite reliable technique where cryptanalysis is quite difficult. It also injects more diffusion and confusion which are the two important attributes of a powerful encryption technique. A comparative study of the proposed encryption scheme and the existing Hill cipher scheme is made. The output encrypted images reveal that the proposed technique is quite reliable and robust.
[1]
Lester S. Hill.
Cryptography in An Algebraic Alphabet
,
1929
.
[2]
Lester S. Hill.
Concerning Certain Linear Transformation Apparatus of Cryptography
,
1931
.
[3]
William Stallings,et al.
Cryptography and Network Security: Principles and Practice
,
1998
.
[4]
G. R. Blakley.
Twenty years of cryptography in the open literature
,
1999,
Proceedings of the 1999 IEEE Symposium on Security and Privacy (Cat. No.99CB36344).
[5]
Shujun Li,et al.
On the security of an image encryption method
,
2002,
Proceedings. International Conference on Image Processing.
[6]
Christof Paar,et al.
An instruction-level distributed processor for symmetric-key cryptography
,
2005,
IEEE Transactions on Parallel and Distributed Systems.
[7]
Jeffrey Overbey,et al.
ON THE KEYSPACE OF THE HILL CIPHER
,
2005,
Cryptologia.
[8]
M.I. Aziz,et al.
Introduction to Cryptography
,
2002,
2005 International Conference on Microelectronics.
[9]
Mohammed Amin,et al.
How to repair the Hill cipher
,
2006
.
[10]
A. Vinaya Babu,et al.
A Large Block Cipher Using Modular Arithmetic Inverse of a Key Matrix and Mixing of the Key Matrix and the Plaintext
,
2006
.
[11]
Saroj Kumar Panigrahy,et al.
Novel Methods of Generating Self-Invertible Matrix for Hill Cipher Algorithm
,
2007
.
[12]
Guanrong Chen,et al.
Cryptanalysis of an image encryption scheme based on the Hill cipher
,
2007,
ArXiv.
[13]
Ganapati Panda,et al.
Invertible, Involutory and Permutation Matrix Generation Methods for Hill Cipher System
,
2009,
2009 International Conference on Advanced Computer Control.
[14]
Autar Kaw,et al.
Introduction to Matrix Algebra
,
2008,
Modern Ophthalmic Optics.