Transposition ciphers change the position of the units that make up a message so that the message contents remain the same, though the order is jumbled so that it appears unintelligible. Generally, transposition ciphers offer little security and can easily be broken by even an amateur crypanalysist (ie: you.) Transposition ciphers take on many appearances and vary widely in security. A rare few rearrange the words of a message while the majority jumbles the letters (which at least provides a bit more security.)

The following encipherment was created using a very simple transposition cipher in which the order of the letters of each word are reversed.

plaintext: a witty saying proves nothing - Voltaire
ciphertext: a yttiw gniyas sevorp gnihton

As you can see, this transposition provides almost no security and the message can be read with little difficulty. The fatal mistake of this transposition is that it keeps the word divisions of the plaintext intact and does not perform a transposition on the entire message. In the example below, the entire plaintext was grouped together and then reversed.

plaintext (original): a witty saying proves nothing
plaintext (modified): awittysayingprovesnothing
ciphertext: gnihtonsevorpgniyasyttiwa

Although this does not make it anywhere near secure (perhaps even less so), it allows us to create more of a challenge. If one were to take another simple step and split the enciphered text into regular groups of five, the word divisions would be slightly less obvious. And since the number of letters used does not divide evently, this also gives us the opportunity to add in three nulls at the end ('zod') to further confuse (a null is simple a character placed in the message to confuse or take or space, or both).

plaintext (original): a witty saying proves nothing
plaintext (modified): awittysayingprovesnothing
ciphertext (original): gnihtonsevorpgniyasyttiwa
ciphertext (grouped): gnih tons evor pgni yasy ttiw azod

NOTE: Grouping text into regular blocks also increased the reliability of accurate transfer. Most enciphered messages were sent using morse code during the golden age of radio and breaking the messages into standard groups of five allowed easier transmission and reception.

Most transposition ciphers employ complex routines to rearrange the letters of the entire message (not just each word separately). In the following pages we will explain how to perform two of the more popular transposition ciphers for rearranging letters, and also how to crack them.

Now that you know a bit about the concepts of transposition ciphers, let's see those concepts in action with a geometric (or route) transposition system...