Double Columnar Transposition Cipher Decoder and Encoder

The double transposition cipher is considered one of the most secure ciphers that can be performed by hand. It is equivalent to using two columnar transposition ciphers, with same or different keys. During World War I and II, it was used by various agents and military forces.

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Double Transposition Cipher Tool

You must enter the message.

Knowing the encryption key

Not knowing the key


Need to customize the output? Click the Options button.


Key Text

Still not seeing the correct result? Then try experimenting with the Auto Decrypt options or use the Cipher Identifier Tool.


Options

Text processing


Grid


        

Features

  • The double transposition cipher is an example of transposition cipher.
  • Until the VIC cipher, the double transposition cipher was considered as the most complicated cipher that an agent could operate reliably by hand.
  • It can encrypt any characters, including spaces and punctuation, but security is increased if spacing and punctuation is removed.
  • The message does not always fill up the whole transposition grid. The remaining of the transposition grid can then optionally be filled with a padding character, or left blank.
  • If the same key is used for encrypting multiple messages of the same length, they can be compared and attacked using a method called "multiple anagramming", finding solutions to both.

Sample Double Columnar Transposition Cipher Text

Code-breaking is not only fun, but also a very good exercise for your brain and cognitive skills. Why don’t you try breaking this example cipher:

mnhol eaiut lciwa tareb bmpfo nnorf edtfe sgeso cefag ditto iobog hmeym bocoe netlc naecy ohanr ssitt toeee ohdfi getno tnhge eiaai tommi tuwvr hosik gdsel onnlh peeee regau tmsay goo