Modern Cryptographic Algorithms and Their Implementations

When the keys for encryption and decryption are the same in a cryptosystem, it is a symmetric cipher. Otherwise, it is a public key/asymmetric cipher. In this chapter, we will detail the designs of three symmetric block ciphers—DES, AES, and PRESENT as well as one public key cipher—RSA. We will also discuss how RSA can be used for digital signatures. Moreover, we will present different techniques for implementing those algorithms.