ADFGVX Cipher Encoder Decoder
Encrypt letters and digits into ADFGVX cipher text or decrypt an ADFGVX message back to readable text.
Use a keyworded 6x6 square and a columnar transposition key to explore this expanded World War I cipher.
- ADFGVX is a fractionating cipher built from substitution plus transposition.
- Its 6x6 square supports the alphabet and digits 0 through 9.
- Use one keyword for the square and another for column order.
- It is historical and educational, not secure modern encryption.
The ADFGVX cipher is a fractionating cipher that starts with a keyed Polybius square. Each plaintext letter or digit becomes a two-letter coordinate using the labels A, D, F, G, V, and X.
A columnar transposition cipher is a cipher that writes text across rows under a keyword, then reads columns in sorted keyword order. In ADFGVX, this second step scrambles the coordinate stream after substitution, making it harder to read direct symbol patterns.
The historical ADFGVX cipher expanded the earlier ADFGX system by adding the coordinate letter V and using a 36-cell square. This tool follows the common A-Z plus 0-9 version for practical encoding and decoding.
Plain text
ATTACK AT 1200
Square keyword: CIPHER | Transposition key: CARGO
Digits fit directly into the 6x6 square before the coordinate stream is transposed.
Plain text
MEET AT GATE 7
Square keyword: RADIO | Transposition key: TRAIN
Changing either keyword changes both the substitution table and the final column order.
ADFGVX was introduced by the German Army in 1918 as an expansion of the ADFGX cipher. The coordinate letters were selected because A, D, F, G, V, and X are distinct enough in Morse code to reduce telegraph copying errors.
ADFGVX is historically important because it combines substitution, fractionation, and transposition in a hand-operable system. The 6x6 square made number-heavy military traffic easier to encode than with the older 5x5 ADFGX variant.
Today, ADFGVX is best used for classroom cryptography, puzzle design, escape-room clues, CTF warmups, and demonstrations of how layered classical ciphers can still be attacked with enough ciphertext and context.
6x6 Square
ADFGVX keeps A through Z and 0 through 9 in one keyed grid, so J does not need to merge with I.
Two Keys
The square keyword controls substitution while the transposition key controls the final column permutation.
Educational Use
Use it for historical learning, classroom exercises, CTF warmups, and puzzle construction.