Editing ADFGVX cipher (section)

== ADFGVX ==
In June 1918, an additional letter, {{code|V}}, was added to the cipher. That expanded the grid to 6 × 6, allowing 36 characters to be used. That allowed the full alphabet (instead of combining {{code|I}} and {{code|J}}) and the [[numerical digit|digit]]s from {{code|0}} to {{code|9}}. This mainly had the effect of considerably shortening messages containing many numbers.

The cipher is based on the 6 letters ADFGVX. In the following example the alphabet is coded with the Dutch codeword '{{lang|nl|nachtbommenwerper}}'. This results in the alphabet: NACHTBOMEWRPDFGIJKLQSUVXYZ. Digits are inserted after the first occurrences of the letters A (1), B (2) to J (0). This creates the table below with the letters ADFGVX as column headings and row identifiers:

{| class="wikitable"
|-
!  !! A !! D !! F !! G !! V !! X
|-
! A 
| N || A || 1 || C || 3 || H
|-
! D 
| 8 || T || B || 2 || O || M
|-
! F 
| E || 5 || W || R || P || D
|-
! G 
| 4 || F || 6 || G || 7 || I
|-
! V 
| 9 || J || 0 || K || L || Q
|-
! X 
| S || U || V || X || Y || Z
|}

The text 'attack at 1200am' translates to this:
{| class="wikitable"
|-
! A !! T !! T !! A !! C !! K !! A !! T !! 1 !! 2 !! 0 !! 0 !! A !! M
|-
| AD || DD || DD || AD || AG || VG || AD || DD || AF || DG || VF || VF || AD || DX
|}

Then, a new table is created with a key as a heading; the following example uses 'PRIVACY' as a key, but usually much longer keys or even phrases were used.
{|
|-
! P !! R !! I !! V !! A !! C !! Y
|-
| A || D || D || D || D || D || A
|-
| D || A || G || V || G || A || D
|-
| D || D || A || F || D || G || V 
|-
| F || V || F || A || D || D || X
|}

The columns are sorted alphabetically, based on the keyword, and the table changes to this:
{|
|-
! A !! C !! I !! P !! R !! V !! Y
|-
| D || D || D || A || D || D || A
|-
| G || A || G || D || A || V || D
|-
| D || G || A || D || D || F || V 
|-
| D || D || F || F || V || A || X
|}

Then, appending the columns to each other results in this ciphertext:
<br />
'''DGDD DAGD DGAF ADDF DADV DVFA ADVX'''

With the keyword, the columns can be reconstructed and placed in the correct order. When using the original table containing the secret alphabet, the text can be deciphered.

This cipher might be modified by transposing the rows as well as the columns, creating a harder but improved cipher.