Cryptanalyzing an image encryption algorithm based on scrambling and Veginere cipher
This work addresses security vulnerabilities in multimedia encryption for researchers and practitioners, but it is incremental as it builds on prior cryptanalysis.
The paper tackles the problem of cryptanalyzing an image encryption algorithm based on scrambling and Veginere cipher by improving a chosen-plaintext attack to reduce the number of required plaintexts to an optimal level and introducing an efficient known-plaintext attack, with verification through mathematical analysis and simulations.
Recently, an image encryption algorithm based on scrambling and Vegin`ere cipher has been proposed. However, it was soon cryptanalyzed by Zhang et al. using a combination of chosen-plaintext attack and differential attack. This paper briefly reviews the two attack methods proposed by Zhang et al. and outlines the mathematical interpretations of them. Based on their work, we present an improved chosen-plaintext attack to further reduce the number of chosen-plaintexts required, which is proved to be optimal. Moreover, it is found that an elaborately designed known-plaintex attack can efficiently compromise the image cipher under study. This finding is verified by both mathematical analysis and numerical simulations. The cryptanalyzing techniques described in this paper may provide some insights for designing secure and efficient multimedia ciphers.