CODEX Maker

Generate custom codebooks for use with the CODEX codebook cipher app. Configure word count, homophone density, character sets, and more, then export as JSON or TSV for import into the app.

Code Format

Codebook seed / keyword Use a long, unique seed (prime length recommended). Leave blank for a strong 37-character default.

Group length

Code characters

a–z A–Z 0–9

Vocabulary

Word count (approx.)

Phrases

Include AWL

Homophones

Letters, words, spaces, punctuation

Digrams & trigrams

Higher = more homophones per token, weighted by English frequency. At 1x, common letters like “e” already get 12 codes while “z” gets 1.

Null Codes

Number of null code groups

Null codes are dummy code groups that the encoder can insert at random positions. They disrupt frequency analysis by adding noise. The decoder recognizes and silently strips them. More null codes means more variety in the inserted dummies.

Additive Pad (companion key, optional)

An additive pad is a separate one-time-use key that goes alongside the codebook. When the CODEX App is set to Additive superencipherment, it adds the pad character-by-character to every code character (mod 62), making the result statistically indistinguishable from a one-time pad. For the most realistic re-enactment, generate both a codebook and a long companion pad here, share both with your recipient, and use one chunk of the pad per message.

Pad length (random base-62 characters)

One-time use: never reuse a pad for another message. If you do, an attacker can XOR the two ciphertexts together to cancel the pad and recover information about both plaintexts (the “depth” attack that broke real one-time-pad systems in WWII). Generate a fresh pad — or take a fresh chunk of a long pad — for every message.

Custom Word List (optional)

Upload word file (one word per line)

Custom list mode

Add to default Replace default

Capacity:

loading word list…

Export for import into the CODEX app

– Tokens

– Codes

– Phrases

– Words

– Trigrams

– Digrams

– Letters

– Special

Security Guidance

How long will this codebook resist cryptanalysis? That depends on how many homophones you use and how much ciphertext you produce before changing the codebook. More homophones require an attacker to collect more ciphertext before frequency analysis, bigram context, or distributional clustering can break the code. See the CODEX Decryptor for a live demonstration of these attacks.

Codebook Viewer

Phrases

Words

Trigrams

Digrams

Letters

Special

Disclaimer: these pages are educational demos provided as-is, with no warranty of any kind. The author is not responsible for any consequences arising from their use.

Send comments and bug reports to chris@chrisspackman.com.

Version 0.4 — Last updated: 2026-05-25

This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.