Double Transposition Cipher Decoder and Encoder

The double columnar 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.
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You must enter the encryption key.
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You must enter the encryption key.
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Auto Solve Options


Instructions

You can decode (decrypt) or encode (encrypt) your message with your key. If you don't have any key, you can try to auto solve (break) your cipher.

Settings
  • Language: The language determines the letters and statistics used for decoding, encoding and auto solving.
  • Min/Max Key Length: This is the search range for keys when auto solving a cipher.
  • Max Results: This is the maximum number of results you will get from auto solving.
  • Spacing Mode: This is about the spaces (word breaks) in the text. In most cases it should be set to Automatic. In case a specific letter (for instance X) is used as word separator, set it to Substitute.

Not seeing the correct result? Try Auto Solve or use the Cipher Identifier Tool.


Auto Solve results

Score Key Text

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


Grid

Enter the key and click decode or encode to show.

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:

ehtmh awftm asowr aseoe hthnt ennsh auret tduia lesnh wtgen aehms ioenh rfoet tlwla tepei sihld gtehe lhhub wtora wsewo r