A Course in Mathematical Cryptography

6 Some Number Theoretic Algorithms

6.1   Number Theoretic Algorithms for Public Key Cryptography

Number theory plays a prominent role in many areas of cryptography. In the simplest case, to develop a cryptosystem for an N letter alphabet, we consider the letters as integers modulo N. As described in Chapter 5, the integers modulo N form a ring called the modular ring _N and encryption is done using algebraic operations on this ring. The totality of operations within the various modular rings is called modular arithmetic. The encryption algorithms then apply number theoretic functions and use modular arithmetic on these integers. Hence encryption ...