ADFGX cipher decoder and encoder

The ADFGX cipher was used by the German Army during World War I. It was invented by Lieutenant Fritz Nebel and is a fractionating transposition cipher which combines a Polybius square with a columnar transposition. The name comes from the five possible letters used: A, D, F, G and X. These particular letters were chosen because they are very different from each other in Morse code, which reduced the risk of telegraphy operator errors. Later, the letter V was added to the ADFGX cipher so it could represent more characters and became known as the ADFGVX cipher.

ADFGX cipher tool

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Polybius square


                    
Transposition grid

                    

                


            

        


        
Features

        
    
            
  • The ADFGX cipher is a combination of a Polybius square and a columnar transposition cipher.
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  • It is simple enough to be possible to carry out by hand.
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  • It can encrypt 25 characters. Because the alphabet has 26 letters, one letter has to be replaced by another (for example replacing j by i).
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  • During World War I, the Germans believed the cipher was unbreakable. It was however broken by a French cryptanalyst in 1918. As a direct result, the French army discovered where the Germans were planning to attack.
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Sample text

        
DXXADDDDADDAADFFAGGFXDXXFFAXGGAXFDADGDFFGXAAFF

        
The ciphertext above represents "LET THE GREAT PLOT COMMENCE" encrypted using the keys POLYBIUS and SQUARE.

    






    

        

            See also: Code-Breaking overview
                 | Adfgvx cipher
                 | Affine cipher
                 | Atbash cipher
                 | Baconian cipher
                 | Beaufort cipher
                 | Bifid cipher
                 | Caesar cipher
                 | Columnar transposition
                 | Cryptogram
                 | Double transposition
                 | Enigma machine
                 | Four-square cipher
                 | Gronsfeld cipher
                 | Keyed caesar cipher
                 | One-time pad
                 | Pigpen cipher
                 | Playfair cipher
                 | Rail fence cipher
                 | Rot13
                 | Route transposition
                 | Trifid cipher
                 | Variant beaufort cipher
                 | Vigenere cipher