Passphrase generator
Generate memorable Diceware-style passphrases from a built-in list of 1200 short English words, with a configurable word count, separator, case transform and optional number and symbol, plus entropy and crack-time estimates.
Runs in your browserEvery computation happens in your browser — your data never leaves this device.
Options
The built-in word list holds 1200 common 3–6 letter English words; randomness comes from crypto.getRandomValues and words are drawn with rejection sampling so the modulo never biases the choice.
Your passphrase
Press "Generate passphrase" to start.
What this tool does
- Pick a memorable but hard-to-guess passphrase for Wi-Fi, a server or full-disk encryption: five words is roughly 51 bits of entropy, far beyond "birthday + exclamation mark".
- Give every service its own secret — generate a fresh phrase instead of reusing one password everywhere.
- Explain password strength to a colleague: turn on the number and symbol options and compare the entropy and crack times to show why an extra word beats an extra symbol.
- When a passphrase has to be written down or read aloud, use a separator and lowercase so the words stay legible.
Example
Input
3 words, separator -, lowercase, no number or symbol (with a fixed random source the first three words are used)
Output
Entropy = 3 × log2(1200) ≈ 30.69 bits, average guesses ≈ 2^29.69, a three-word phrase such as able-add-age
A real click draws every word at random; this only shows the arithmetic: a 1200 word list gives about 10.23 bits per word.
Frequently asked questions
Why is an extra word better value than an extra symbol?
Each word adds log2(1200) ≈ 10.23 bits, while a symbol adds only log2(13) ≈ 3.7 bits and a two digit number about 6.6 bits. Words are also easier to remember: a six word phrase is simpler to retype than twelve random characters.
Where does the word list come from?
It is a self-authored list of 1200 common 3–6 letter English words embedded in the source, with no external file loaded and no copy of the official 7776 word Diceware list. Words are drawn with rejection sampling, so no value is favoured by the modulo operation.
How are the entropy and crack times calculated?
Entropy is words × log2(word list size), plus log2(100) for the number and log2(13) for the symbol when enabled. Crack time assumes an attacker needs half the keyspace on average, across three scenarios: online (1000 guesses/s), offline slow hash (10k/s) and offline fast hash (10 billion/s).
Does random casing add strength?
Barely, which is why it is not counted as entropy: attackers simply try the case variants. It only makes the word boundaries harder to spot at a glance. Real strength comes from adding words.
Is the passphrase uploaded or logged?
No. The word list lives in the page, randomness comes from crypto.getRandomValues, and nothing is sent anywhere. A refresh clears the result and no history is kept.
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