Diceware · runs with no network

Offline Passphrase Bench

Every word and character pool below is editable. Randomness comes from the browser's cryptographic generator with rejection sampling, so no value is more likely than any other.

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0bits of entropy –
–average guess time at 100 billion tries/second
    Word list — 0 words, 0 bits each

    One word per line or separated by spaces. Duplicates and non-letters are dropped when the list is read. Entropy recalculates from whatever is actually in this box.

    How to use it offline. Save this page as a single .html file and open it from disk. It loads no fonts, scripts, or data from anywhere, and nothing you generate leaves the page. Settings are kept in this browser's local storage; passphrases never are.

    On the numbers. Entropy assumes an attacker knows exactly how the passphrase was built and only has to guess the random choices — the right assumption to make. Average guess time is half the search space at 1011 guesses per second, roughly a well-funded offline attack on a fast hash. A well-run service rate-limits to a few guesses per second, which makes 60 bits plenty; use 80+ for anything that protects a vault or a key.

    The default list is the EFF long wordlist (7,776 words, 12.92 bits each), chosen for words that are easy to type and hard to mistype. Four hyphenated entries were spelled without hyphens so separators stay unambiguous.

    Black Sheep Systems.

    Built in-house as internal tooling and released as-is. No warranty, no support commitment, and no data of any kind leaves this page.

    Massachusetts · Est. 2026