On the Affine Ciphers in Cryptography

Abstract

Before letter frequency analysis and the formation of the black chambers, the basic monoalphabetic substitution ciphers were practically unbreakable and sufficient for common use. But as encryption became used more widely, the need to break these cryptosystems became inevitable. With the development of letter frequency analysis and advancement of black chambers, each message encrypted with a type of monoalphabetic substitution was easily broken. As soon as a commonly used monoalphabetic substitution cipher was broken, the word spread and that particular cryptosystem was useless. The affine cipher is simply a special case of the more general monoalphabetic substitution cipher. In this paper, we study the affine cipher and generalized affine cipher.