What is a passphrase?
A passphrase is a secret made of several ordinary words — for example
trombone-cactus-velvet-hijack — instead of a short string of mixed
characters. When the words are picked at random by a computer, a passphrase is just as
hard to guess as a strong password of the same entropy, but far easier for a
person to remember and type. This is the
Diceware method,
using the word lists published by the Electronic Frontier Foundation.
How this generator works
- Each word is an independent, uniform random draw from the list you choose.
- Randomness comes from
crypto.getRandomValues, your browser's cryptographically secure generator — neverMath.random. - Indexes are chosen with rejection sampling, so there is no modulo bias.
- The tool never removes repeated words and never regenerates a result for "looking random" — either would quietly reduce the real strength.
- Everything runs locally. The word lists load once; nothing you generate leaves your device.
How many words should I use?
Entropy is words × log₂(list size). With the EFF large list:
| Words | Entropy | Verdict |
|---|---|---|
| 4 | ~51.7 bits | Only where guesses are rate-limited |
| 5 | ~64.6 bits | Good for everyday accounts |
| 6 | ~77.5 bits | Recommended — master passwords, important accounts |
| 7 | ~90.5 bits | High-value secrets, encryption keys |
| 8+ | ~103+ bits | Overkill for almost everyone |
Six words is the sweet spot. Never go below four.
Making it memorable
Memorability comes from three things, none of which weaken the passphrase:
- The list. The EFF large list was built for recall — no words under three letters, no confusable pairs, common vocabulary, unique three-letter prefixes.
- The right length. Six words is enough to be strong and short enough to learn.
- Your mnemonic. Spend ten seconds inventing a vivid, absurd mental image
that links the words in order. For
trombone-cactus-velvet-hijack: a cactus in a velvet suit playing the trombone during a hijacking. The randomness is untouched; the story is yours.
Do not hand-pick "words that go together" or reroll until the phrase reads like a sentence — that shrinks the search space an attacker has to cover.
Frequently asked questions
Is a Diceware passphrase secure?
Yes. A six-word EFF passphrase is about 77 bits of entropy, which resists offline brute-force for centuries. Security depends only on the words being uniformly random.
Passphrase or password?
At equal entropy they are equally strong; the passphrase is easier to memorise and type. Use the password generator where a length limit rules a passphrase out.
Should I still use a password manager?
Yes. Use a memorable passphrase for the few secrets you must type — your device login, your password manager's master password, disk encryption — and let the manager generate random passwords for everything else.
Related reading: What is a passphrase and why use it · Strong password generator.