Scrambling the message
Transposition ciphers, also called permutation ciphers, rely on rearranging the order of the characters. Despite the letters being permuted throughout the text, the actual content of the message itself is preserved. This is the opposite of substitution ciphers, which keep each character in its right place but change the content of the message. The simplest way to think of transposition ciphers is as anagrams; though the key differences are that the result of a cipher is unintelligible while anagrams usually result in another intelligible word and that ciphers need for a key. Additionally, transposition methods can vary greatly in complexity, giving them a wide range of practical uses.
An ancient example of transpositional ciphers are scytale ciphers. With these, the sender and receiver have identical cylinders. A strip of parchment is wrapped diagonally around one of them, leaving no gaps, before the message is written on it. The security comes from the fact trying to wrap the parchment around an object of any other dimensions would result in gibberish. Another historical example of transposition ciphers was the ADFGVX cipher, used by Germany during World War I. It was sent through Morse code and combined transposition with a Polybius square. The name comes from the possible letters that appear in the encoded message, chosen because they're very different from each other in Morse to reduce the chance of operator error. Click below to hear the six letters used in the ADFGVX cipher.