In this chapter, we focus on symmetric encryption. We begin by identifying two different types of symmetric encryption algorithm, namely, stream and block ciphers. We discuss the basic idea behind a stream cipher and consider their properties and applications. We then introduce block ciphers. We focus on two extremely important and influential block cipher algorithms, the Data Encryption Standard and the Advanced Encryption Standard, discussing the history of their development as well as their basic design. We then introduce the modes of operation of a block cipher, explaining why different modes have been proposed. We examine in detail four of the most well-established modes of operation and their core properties, as well as classifying other modes of operation.
Cloud Computing Security Model with Combination of Data Encryption Standard Algorithm (DES) and Least Significant Bit (LSB)
