RSA-Public Key Cryptosystems Based on Quadratic Equations in Finite Field
The importance of Public Key Cryptosystems (PKCs) in the cryptography field is well known. They represent a great revolution in this field. The PKCs depend mainly on mathematical problems, like factorization problem, and a trapdoor one-way function problem. Rivest, Shamir, and Adleman (RSA) PKC systems are based on factorization mathematical problems. There are many types of RSA cryptosystems. Rabin's Cryptosystem is considered one example of this type, which is based on using the square order (quadratic equation) in encryption function. Many cryptosystems (since 1978) were implemented under such a mathematical approach. This chapter provides an illustration of the variants of RSA-Public Key Cryptosystems based on quadratic equations in Finite Field, describing their key generation, encryption, and decryption processes. In addition, the chapter illustrates a proposed general formula for the equation describing these different types and a proposed generalization for the Chinese Remainder Theorem.