# Breaking caesar ciphers ![centre-aligned Caesar wheel](caesarwheel1.gif) --- # Brute force How many keys to try? ## Basic idea ``` for each key: decipher with this key how close is it to English? remember the best key ``` What steps do we know how to do? --- # How close is it to English? What does English look like? * We need a model of English. How do we define "closeness"?