Investigations on text and image data for secure digital communication

Abstract

newline Multimedia formats such as text, images, audio and video are currently being stored and distributed on a wide range of networks and devices. When an unauthorized user gains access to the system, it is quite easy to copy and redistribute such information. Cryptography has therefore become a necessity to protect the content against unauthorized access. The requirements of encryption techniques vary widely for different forms of data; the demands of image encryption methods are challenging than those of text encryption owing to the intrinsic characteristics of bulk data and elevated redundancy. Not only the encryption techniques need to be secure and fast, the cipher also needs to be as easy to handle, store and transmit as the data newlineGenerally in image encryption algorithms, pixel values are substituted and/or scrambled to reduce the correlation among them when external keys are used. Although it has been shown in studies that scrambling and substitution operation are not sufficient to achieve a secure cipherIt is also important to focus on secure text data communication as it is the most common and basic form of communication. The Double Reflecting Data Perbutation (DRDP) method and hashing are used in the suggested system to provide text data security. The proposed system uses message digest providing integrity with the added advantage of authentication, as only the sender and receiver know the Shared Secret Key (SSK). Thus message digest not only handles integrity but also achieves authentication. Eventhough the cryptographic algorithms are suitable for text encryption it may not be appropriate for other multimedia data such as image data due to their high redundancy and large volume. Highly personal and sensitive image data is handled in fields such as medical and military, it is therefore vital to secure these image data before transmission or distribution. This has led to the need for new and better techniques of image encryption. newline newline