This page analyzes a text’s letter frequency and is an emulation of Tyler Atkin’s page. One application is decoding a Caesar cipher. A Caesar or “shift” cipher is an encryption technique in which each letter in the unencrypted message is shifted over a certain number of positions. For example, A encodes into B and B into C. The cipher is named after Julius Caesar who reportedly used a shift cipher of three to communicate with his generals.
So how do we break a Caesar cipher? One technique is to analyze its letter frequency. In English, certain letters like E and T occur more frequently than others like Q and Z. By getting the shape of the letter frequency distribution and comparing it to the known relative letter frequencies of the English language, we can sometimes determine if a Caesar cipher was used.