SECURITY ENHANCEMENT OF AN IMAGE ENCRYPTION SCHEME BASED ON CHAOTICALLY COUPLED CHAOTIC MAPS
Date
2018-11
Authors
THAPA, SAROJ
Journal Title
Journal ISSN
Volume Title
Publisher
Pulchowk Campus
Abstract
This research aims to enhance the security of image encryption scheme using the
application of chaos theory. Due to some intrinsic features of the images, such as bulk
data capacity and high correlation among pixels, the traditional encryption techniques
such as AES, DES, RSA, etc. are not suitable for image cryptography. So chaos based
image cryptography is introduced to overcome these drawbacks associated with
traditional encryption techniques. This image encryption scheme encompasses
confusion and diffusion stages. During confusion stage, three levels of shuffling using
different chaotic maps are used. In the first level, cubic map is used and Arnold cat
map in the second level followed by tent map. Finally the shuffled image is diffused
using Henon map to produce the ciphered image for transmission. Sensitivity analysis
is performed with respect to key to its security against brute-force attacks. The
average entropy value of 7.97 provides vigorous upon entropy attack. The Number of
Pixel Change Ratio (NPCR) of above 99% obtained from the diffusion stage signify
the use of multiple chaotic maps. The image cryptosystem has 2128
different combinations of the secret keys. The maximum correlation values in vertical,
horizontal and diagonal directions of encrypted images are 0.0826, 0.0772 and 0.0721
respectively and structured similarity index measurement of not more than 0.0152
between original image and encrypted image validates the robustness of this
algorithm.
Description
This research aims to enhance the security of image encryption scheme using the
application of chaos theory. Due to some intrinsic features of the images, such as bulk
data capacity and high correlation among pixels, the traditional encryption techniques
such as AES, DES, RSA, etc. are not suitable for image cryptography.
Keywords
Chaos Theory, Tent map, Cubic map, Arnold cat map