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Security and Communication Networks
Volume 2017, Article ID 7367518, 13 pages
Research Article

Two-Phase Image Encryption Scheme Based on FFCT and Fractals

Department of Engineering Mathematics, Faculty of Engineering, Alexandria 21544, Egypt

Correspondence should be addressed to Mervat Mikhail; moc.liamg@08liahkim.tavrem

Received 19 July 2016; Revised 21 October 2016; Accepted 20 November 2016; Published 22 January 2017

Academic Editor: Anna Cinzia Squicciarini

Copyright © 2017 Mervat Mikhail et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This paper blends the ideas from recent researches into a simple, yet efficient image encryption scheme for colored images. It is based on the finite field cosine transform (FFCT) and symmetric-key cryptography. The FFCT is used to scramble the image yielding an image with a uniform histogram. The FFCT has been chosen as it works with integers modulo and hence avoids numerical inaccuracies inherent to other transforms. Fractals are used as a source of randomness to generate a one-time-pad keystream to be employed in enciphering step. The fractal images are scanned in zigzag manner to ensure decorrelation of adjacent pixels values in order to guarantee a strong key. The performance of the proposed algorithm is evaluated using standard statistical analysis techniques. Moreover, sensitivity analysis techniques such as resistance to differential attacks measures, mean square error, and one bit change in system key have been investigated. Furthermore, security of the proposed scheme against classical cryptographic attacks has been analyzed. The obtained results show great potential of the proposed scheme and competitiveness with other schemes in literature. Additionally, the algorithm lends itself to parallel processing adding to its computational efficiency.