Medical Image Encryption: An Application for Improved Padding Based GGH Encryption Algorithm.

Massoud Sokouti,Babak Sokouti,Ali Zakerolhosseini

doi:10.2174/1874431101610010011

Abstract

Medical images are regarded as important and sensitive data in the medical informatics systems. For transferring medical images over an insecure network, developing a secure encryption algorithm is necessary. Among the three main properties of security services (i.e., confidentiality, integrity, and availability), the confidentiality is the most essential feature for exchanging medical images among physicians. The Goldreich Goldwasser Halevi (GGH) algorithm can be a good choice for encrypting medical images as both the algorithm and sensitive data are represented by numeric matrices. Additionally, the GGH algorithm does not increase the size of the image and hence, its complexity will remain as simple as O(n2). However, one of the disadvantages of using the GGH algorithm is the Chosen Cipher Text attack. In our strategy, this shortcoming of GGH algorithm has been taken in to consideration and has been improved by applying the padding (i.e., snail tour XORing), before the GGH encryption process. For evaluating their performances, three measurement criteria are considered including (i) Number of Pixels Change Rate (NPCR), (ii) Unified Average Changing Intensity (UACI), and (iii) Avalanche effect. The results on three different sizes of images showed that padding GGH approach has improved UACI, NPCR, and Avalanche by almost 100%, 35%, and 45%, respectively, in comparison to the standard GGH algorithm. Also, the outcomes will make the padding GGH resist against the cipher text, the chosen cipher text, and the statistical attacks. Furthermore, increasing the avalanche effect of more than 50% is a promising achievement in comparison to the increased complexities of the proposed method in terms of encryption and decryption processes.

Highlights

Image encryption is one of the important fields of cryptography and one of the best known algorithms used in this realm is the DES (Data Encryption Standard) algorithm which requires less time while considering the computational costs [1, 2]
The results showed that the avalanche effect value of standard Goldreich Goldwasser Halevi (GGH) algorithm is almost 10% which is far from the literature standards
GGH is a simple public key crypto system which is based on the closest vector problem (CVP)

Summary

Introduction

Image encryption is one of the important fields of cryptography and one of the best known algorithms used in this realm is the DES (Data Encryption Standard) algorithm which requires less time while considering the computational costs [1, 2]. A digital image can be considered as a two dimensional matrix or a square array of numbers. The elements of this array are called pixels. It is meant to apply a symmetric or asymmetric encryption algorithm on an input image to be converted into a cipher image using either symmetric or asymmetric keys [3, 4]. Symmetric ciphers only use one key for encryption and decryption processes while asymmetric ciphers use two different key pairs (i.e., public and private keys) [5]

Methods

Results

Conclusion