The Caesar cipher seems very weak. But looking at a ciphertext, it is hard to know where to start – this hardly seems to be English at all. Perhaps we should start with the Caesar cipher itself, assu...The Caesar cipher seems very weak. But looking at a ciphertext, it is hard to know where to start – this hardly seems to be English at all. Perhaps we should start with the Caesar cipher itself, assuming (anachronistically) that Caesar was following Kerckhoff’s Principle, or that (more chronistically) spies had determined the cryptosystem but not the key.