Designing a new encryption then compression system for grayscale images utilizing entropy encryption

Abstract

In the digital era, images and video sequences have dramatically increased newlinebecause of the rapid growth of the Internet and the widespread utilization of multimedia systems. The advancement in technology facilitates a faster way of transmitting data; however, the channel used for communication is an untrusted medium. The proposed research focus on the secure newlinetransmission of grayscale images over a social networking site (SNS) provider called the untrusted channel. Rigorous research has been conducted on the secure transmission of images and proposed different models, namely Compression-then-Encryption (CtE) Systems and newlineEncryption-then-Compression (EtC) Systems. In EtC, the encrypted information is transmitted over the channel. However, the channel is newlinecompressing the information to reduce the overall traffic. Due to the compression performed by the channel, the decryption process may fail on the receiver side. Constructing an efficient EtC model, as good as the standard compression algorithms, will address the gap in research. Four objectives were formulated, and schemes were proposed for each objective to address the problem. Two schemes were developed to address the first objective, eliminating noise incurred during transmission through the channel. The first scheme eliminates the noise using a two-pass hybrid mean and median filter. In the second scheme, a supervised curve fitting a linear regression model with a mean filter is applied. To secure the transmission of images over the untrusted channel, the objectives two and three address the scrambling and encryption of images. A hybrid of improved Arnold transforms and ElGamal encryption is experimented with in the first scheme to address scrambling and encryption. In this initially, a Block-wise scrambling is applied to the image, followed by pixels-wise newlinescrambling within the block followed by Arnolds transform. The outcome is given to ElGamal encryption.