Substitution Cipher

Introduction We will now tackle another encryption method called affine cipher. If by reading the word affine made you think of affine functions, you are already on the right track! This method uses an affine function to encrypt messages. Differently from the shift cipher that uses only addition, the affine cipher uses also multiplication, which makes our encryption more complex. If we recall how an affine function looks like, it takes an input $x$, multiply by a coefficient, $a$, and adds to a constant, $b$. ...

Introduction In this post we will cover the shift cipher. Although it’s not the first known cryptographic method, it’s one that is very well documented and a great entry point to cryptography. This method makes use of modular arithmetic, so we will be able to put to use the knowledge we have so far. If you are not familiarized with modular arithmetic, I strongly recommend reading the post Introduction to Modular Arithmetic before proceeding. ...