Fractionation / Columnar transposition

ADFGVX cipher encoder and decoder

Encode or decode letters and digits with a keyed 6 by 6 square and an exact columnar transposition.

01 / Workspace

Set the two keys

Mode

The selected direction is always used. The tool never guesses keys or mode.

0 / 128

ASCII letters and digits only. Unique symbols are kept in first-seen order, then unused A-Z and 0-9 are appended.

0 / 64

Required ASCII letters only. Repeated letters are allowed and ranked left to right when their letters match.

0 / 12,000 code points

Enter ASCII letters and digits. Space, tab, CR, and LF are removed; letters are uppercased. All other characters are rejected.

Keyboard: press Ctrl+Enter or Command+Enter in a text or key field to run the selected mode.

Ready to encode.

02 / Key preview

Square and column order

Keyed Polybius square

Rows and columns use A, D, F, G, V, X
A D F G V X

Empty square key: row-major A-Z, then 0-9.

Column read order

Enter a valid transposition key to show its stable alphabetical order.

03 / Result

Encoded ciphertext

No result yet

This intermediate stream shows the row and column coordinate for each normalized plaintext symbol.

Copy returns the final result only, without labels or the intermediate coordinate stream.

04 / Convention

Exact ADFGVX convention

  1. Build the square. Uppercase and stably deduplicate the optional ASCII alphanumeric square key. Append unused ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789, then fill the 6 by 6 square row by row.
  2. Fractionate. Read each normalized plaintext symbol as its row label followed by its column label. Both axes use ADFGVX in that exact order.
  3. Transpose. Write the coordinate stream in rows under the transposition key. Read columns in alphabetical key order. Equal key letters keep their original left-to-right order. No padding is added.
  4. Decode ragged columns. Determine each original column length from the ciphertext length. Earlier original columns own the extra cells in an incomplete last row, even when sorted key letters are repeated.

Deterministic known-answer check

Square key
Empty
Transposition key
GERMAN
Plaintext
ATTACKAT1200
Fractionated
AAGDGDAAAFDVAAGDVGVVVFVF
Ciphertext
GDVVAAAVAAAVDFDFDVGFGAGV

Normalization, limits, and security

  • Encode accepts ASCII A-Z, a-z, and 0-9. It uppercases letters and removes only ASCII space, tab, carriage return, and line feed. Punctuation, accents, emoji, combining marks, and other scripts are rejected, not silently discarded.
  • Decode removes those same four whitespace characters and otherwise accepts only uppercase A, D, F, G, V, and X. Lowercase ciphertext, invalid symbols, and odd coordinate-stream lengths are rejected in full.
  • Raw input is limited to 12,000 Unicode code points. Normalized plaintext is limited to 5,000 symbols and normalized ciphertext to 10,000 symbols. The square key is limited to 128 characters and the transposition key to 64 letters.
  • The preview is bounded to 36 square cells, six row headers, and at most 64 column-order entries. Results are created only after complete validation.
  • Processing stays in this page and adds no network requests or persistent storage. Copying occurs only when you choose Copy result.
  • ADFGVX is a historical classical cipher and is unsuitable for passwords, personal records, or any other sensitive information.