Transposition ciphers encrypts by switching the order of the letters to conceal the message being sent.
This is completely opposite to how simple substitution ciphers like Caesar cipher works (Switching the letters that make up the message).
- Read: Complete list of cipher.
To put it simply, letters in transposition ciphers are just moved around. You reorder the letters of your plaintext using a given key.
In this guide I will be discussing the following:
- Transposition ciphers examples and how to solve them.
- Advantages of transposition ciphers and evaluation of how secure they are.
1) Transposition ciphers examples and how to solve them
Here are seven transposition ciphers.
Rail fence cipher
Rail fence is a transposition cipher in which plaintext is written downwards on successive rails of an imaginary fence, then moving up when you get to the bottom.
The message is read off in rows.
Here is an example of rail fence cipher:
Plaintext: Hello world.
Ciphertext: Horel ollwd
Here is an online interactive rail fence tool to encode and decode simple messages.
Route cipher is a transposition cipher where the key is the route to follow when you are reading the ciphertext from the block created with the plaintext.
Often the plaintext is written in a grid, and then read off following the route chosen.
Here is an example of route cipher:
Plaintext: We are discovered. Free at once.
Ciphertext: EJX CTE DEC DAE WRI ORF EON ALE VSE
In columnar transposition, plaintext is written out in rows and then the ciphertext is read off in columns.
Is a form of route cipher in which the route is to read down each column in order.
Here is an example of columnar transposition cipher:
Plaintext: Message from Mary Stuart kill the queen.
Ciphertext: NMOAE ARIER UHSAK EFTTE MRQ
Here is a columnar transposition encoder/decoder that you can use to learn how this cipher works.
Double transposition (double columnar transposition) cipher is a columnar transposition followed by another columnar transposition.
Here is an example of double transposition cipher:
Here is a double transposition cipher encoder/decoder to learn how this cipher encrypts and decrypts messages.
Grilles form a kind transposition cipher with a slight aspect of stenography which consists of pieces of cardboards with holes cut into them in a specific pattern.
Here is an example of grilles:
Scytale is a transposition cipher device that was used by the Ancient Greeks and Spartans. It has a polygonal rod or cylinder, with a piece of parchment wrapped around.
A message is written along the faces of the rod and when the parchment is removed from the Scytale, it leaves a scrambled up message down the strip.
To decode a message, simply wrap it around a rod of the same size and shape as the original, to show the original message.
Here is an example of Scytale:
Myszkowski transposition cipher is a variant of columnar transposition that deals with recurring letters in the keyword. It was proposed by Émile Victor Théodore Myszkowski in 1902.
Usually the plaintext is written down in rows under the keyword. In case of repeated letters in the keyword, give all the same letters the same number.
You then read across columns which have the same number in the keyword.
Here is an example of Myszkowski transposition cipher:
Plaintext: The tomato is a plant in the nightshade family.
“At the top of the grid, the keyword is written, to show how many columns there needs to be in the grid. Beneath this are the numbers giving the alphabetical order of the letters of the keyword”.
Ciphertext: TINES AXEOA HTFXH MTALI TIHAE IYXTO ASPTN NGHDM LX
2) Advantages of transposition ciphers and evaluation of how secure they are
The advantage of transposition ciphers is that they are less prone to frequency analysis attacks, since the symbols of each character are not changed but only their positions.
This means that if you have letter “a” 10 times in your plaintext, you will also have letter “a” 10 times in the ciphertext.
- Read: Playfair Cipher.
Transposition ciphers are no longer secure for sending messages since there are techniques of breaking them and their methodology is easy to decode.
What aspect of transposition ciphers was unclear to you?
Let me know by leaving a comment below.