Performance analysis of diverse techniques to improve the confidentiality of image Cryptosystems

Abstract

Development in technology has led to the improvisation of various tools in communication which has made transfer of information easier. Exchange of digital data between the communicating parties in a protected and controlled environment is the need of the day. With the advancement in the connectivity among various digital entities, the access to outside world has increased to a larger extent. Measures to avoid disclosure of information by any unauthorized users before enduring any loss of information should be taken care of. Confidentiality, integrity and authentication are the three important security features needed to be addressed in the secured transmission of data. Encryption offers an appropriate solution to achieve these security features. In this regard, an attempt to explore the possibilities of combining various encryption techniques for secured transmission of images has been done in this work. This thesis provides a structured and comprehensive study of various encryption techniques to offer confidentiality, authentication and integrity in transmission of images. A cipher scheme using two bit and four bit pixel expansion to divide the image into meaningless shares is done using two out of two visual cryptography. The bit planes obtained by binary bit plane decomposition are further diffused to uncorrelate the pixel values. These shares are encrypted using the symmetric cipher RC6 to provide confidentiality. The quality of the decrypted image is analyzed using image quality parameters such as Peak Signal to Noise Ratio, Mean Squared Error, Correlation Coefficient and Structural Similarity Index Measure. The resistance of the cryptosystem against the statistical attacks is analyzed using histogram analysis and correlation of adjacent pixels. A security system using electronic code book block modes using DNA cryptography wherein the image is diffused through the asymmetric encryption scheme RSA is compared with the same scheme without using block modes. The performance of the encryption scheme is also a