ADFGX cipher

Use it free in the browser for history-of-crypto lessons, puzzle design, and reversible lab demos, or call the API at $0.002 per successful request when pipelines need reproducible ADFGX transforms without re-implementing fractionation and grid packing yourself.

What the ADFGX cipher is and what this tool returns

The JSON response includes result for the ciphertext or recovered plaintext, mode set to encrypt or decrypt, square_key and key echoing the keywords you supplied, letters_mapped and fractionated_length for the digraph stage, key_length and column_order for the transposition stage, alphabet as the twenty-five-letter fill of the square, labels fixed to ADFGX, cipher fixed to adfgx, and a formula string that restates the two-stage contract for documentation and tests. There is no streaming path and no silent fallback to Vigenère or modern AES: either you supply text plus both keys under the documented rules, or the request fails with invalid_input. If you need only a plain Polybius digit map, only columnar rearrangement, or authenticated modern encryption, use those dedicated endpoints; this landing answers the combined ADFGX workflow that crypto history chapters and CTF warm-ups already describe.

How text, square_key, key, and mode are read and how results stay reproducible

Column order is computed once from the transposition key, and the same heights formula is used on encrypt and decrypt so a round trip always restores the original letters for any message that contains Latin letters under those two keywords. The preferred payload fields are text for the message, square_key for the Polybius keyword, key for the transposition keyword, and optional mode for encrypt or decrypt. Text accepts aliases such as input, value, s, message, plaintext, and ciphertext so forms and SDK clients can reuse existing column names without renaming every call site. Square_key accepts square_keyword, polybius_key, and square; it must contain at least one Latin letter after case folding, otherwise the engine raises invalid_input with a clear empty square_key message. Key accepts transposition_key, keyword, k, password, and passphrase; the entire non-empty string defines the columns, including digits and symbols if you include them, because ordering uses character comparison with Latin letters sorted case-insensitively and stable left-index ties on repeats. An empty transposition key is rejected with invalid_input. Mode defaults to encrypt when omitted and also accepts short aliases such as enc, encode, e for encrypt and dec, decode, d for decrypt; any other string fails validation. Missing text, missing keys, non-string types, letter-free encrypt plaintext, ciphertext with no ADFGX symbols, and odd digraph streams after the transposition undo all raise invalid_input so a blank form does not look like a successful no-op. Pair the free browser run on this page with the priced API when you need the identical ADFGX transform inside an automated pipeline without re-implementing digraph fractionation yourself. Invalid inputs return invalid_input and are not charged, which keeps validation cheap while successful transforms remain a fixed item price of $0.002.

Where ADFGX fits in lessons, puzzles, and test fixtures

On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split — free interactive exploration and a priced, identical API — matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the ciphertext.