2  Caesar cipher

What is the airspeed velocity of an unladen swallow?

Password:

2.1 Introduction

The Caesar cipher is the most basic type of encryption that we will look at. It is extraordinarily simple to use: each character of the alphabet is simply mapped to another character a fixed number of alphabet away.

For example, using a shift of 2, A would be turned into C, B into D, and so on, all the way until the end where X is turned into Z, Y back into A, and Z into B.

You can try out the Caesar cipher with this simple form here:

Encrypt
Decrypt
Shift: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

2.2 Breaking a Caesar cipher

Since there are only 25 useful possibilities for encoding, it is almost trivial to break a Caesar cipher. You can perform a brute-force attack, which means trying each possibility until you find one that gives the correct text. For example, use the playground above to figure out this hidden message:

OPKKLUTLZZHNL