Dice Entropy Check

An offline fairness test for dice used to generate Bitcoin seeds. Built for 16-sided binary dice (faces 0000–1111), and also works for 2, 4, 6, 8, 10, 12 and 20-sided dice.

Record your test rolls by tapping faces (or typing hex digits), and the page runs a chi-square goodness-of-fit test, a per-bit balance test, and flags faces that show up far more or less often than expected. Runs can be saved in your browser and exported as CSV or JSON.

Test rolls only. Never enter the rolls you'll use for a real seed, here or in any other tool.

Use it

• Online / install as an app: open https://dice.cypherhive.com, then on iPhone tap Share → Add to Home Screen, or on Android / desktop Chrome / Edge choose Install app. After the first visit it works with no connection.
• Fully offline: download dice-entropy-check.html from the latest release and open it in any browser. It's a single self-contained file.

Don't trust, verify

1. Read it. All of the logic is in index.html (identical to the release's dice-entropy-check.html): plain HTML, CSS and JavaScript with no dependencies, no build step, and no external resources. sw.js is a ~50-line service worker that only caches this app's own files for offline use.

2. Network access is blocked. The page's Content-Security-Policy starts with default-src 'none', so the browser refuses fetch, XHR, WebSocket, beacons, fonts and form posts. The only same-site files it may load are its own icon, manifest and sw.js. Confirm the code never assigns to location or calls window.open.

3. Test it offline. Turn on airplane mode and open it. Everything works.

4. Check the hash against SHA256SUMS and the author's signed Nostr announcement:

   shasum -a 256 --ignore-missing -c SHA256SUMS         # macOS / Linux
   certutil -hashfile dice-entropy-check.html SHA256     # Windows

5. Check the math. Export your rolls as CSV and re-run the test elsewhere, e.g. scipy.stats.chisquare(counts) in Python. The p-values match SciPy to machine precision.

Signed announcement

Each release's hash is also published in a Nostr note signed by the author's key, so a copy of this repo or website that's been tampered with can be caught even if GitHub or the domain were compromised.

v1.0.0 — signed note on Nostr

1c4942b43136a238b161c8216ae1ea7aae0faea7c6c061ba9eba800166f6f78c  dice-entropy-check.html

How to check it:

1. Hash your copy of the file (commands above) and confirm it matches the hash in the note.
2. Open the note in any Nostr client. Clients verify the note's Schnorr signature automatically, so the text can't have been altered since it was signed. To check it yourself, fetch the raw event JSON and verify its signature with a command-line Nostr tool such as nak.
3. Confirm the note's author is the real @ChuckinBitcoin key: it's the same npub that posts as @ChuckinBitcoin on Nostr and is linked from the author's other profiles. Watch out for look-alike accounts.

A matching signature shows the file is the one the author published. It does not by itself prove the code is safe; that's what reading it (step 1 above) is for.

Files

File	Purpose
index.html	The whole app
sw.js	Offline cache for the installable version
manifest.webmanifest	App name and icons for installing
icons/	App icons
SHA256SUMS	Hashes of every file
CNAME	Custom domain for GitHub Pages

Host your own copy

Upload the folder to any static web host (it can live in a subfolder such as /dice/). HTTPS is required for the install-as-app feature; the page itself works anywhere.

When you change any file, bump VERSION in sw.js so installed copies pick up the update, then regenerate the hashes:

cp index.html dice-entropy-check.html
shasum -a 256 index.html dice-entropy-check.html sw.js manifest.webmanifest icons/* > SHA256SUMS
rm dice-entropy-check.html

Credits

Built by @ChuckinBitcoin (Nostr & X). Statistics based on the original chi-square fair-die spreadsheet by @ineedanewgame.

License

MIT. See LICENSE.