ProtemKey

Passphrase · password · PIN

Keys you can trust.

Random words and characters picked by your browser's cryptographic generator, with the strength computed exactly from the settings and explained in plain numbers. Nothing you generate or type is stored or sent.

  • Runs entirely in your browser
  • One tap to copy
  • Tested in public: see the results
A key whose teeth rise like an entropy bar chart, in front of a grid of random bits and a padlock
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Why it is strong

77.5 bitsVery strong
  • 6 words, each one of 7,77677.5 bits

7,776⁶ ≈ 2.2 × 10²³ equally likely passphrases.

Online, rate-limitedabout 1017 years100 guesses per hour
Offline, slow hash350 billion years10,000 guesses per second
Offline, fast hash35 thousand years100 billion guesses per second

Average time to guess (half of all possibilities). The rates are illustrative assumptions, not measurements.

How strong is strong?

A secret chosen at random has an exact strength: the number of equally likely possibilities, counted in bits. Every extra bit doubles the work for anyone guessing. Here is what that means at three illustrative attack rates.

Average time to guess (half of all possibilities) for secrets chosen uniformly at random. Rates are illustrative assumptions; human-chosen passwords fall far faster than their length suggests.
SecretBitsOnline, 100/hourSlow hash, 104/sFast hash, 1011/s
4-digit PIN13.32.1 daysless than a secondless than a second
6-digit PIN19.9208 days50 secondsless than a second
8 random lowercase letters37.6119 thousand years121 days1 second
8 random printable characters52.43.5 billion years9.7 thousand years8.5 hours
12 random letters and digits71.5about 1015 years5.1 billion years511 years
3 random EFF words38.8268 thousand years272 days2.4 seconds
4 random EFF words51.72.1 billion years5.8 thousand years5.1 hours
5 random EFF words64.616 trillion years45 million years4.5 years
6 random EFF words77.5about 1017 years350 billion years35 thousand years
7 random EFF words90.5about 1020 yearsabout 1015 years272 million years
16 random printable characters104.9about 1025 yearsabout 1019 years5.9 trillion years
20 random printable characters131.1about 1033 yearsabout 1027 yearsabout 1020 years

Try your own numbers in the crack-time calculator

Tools

Passphrase generatorRandom words from the EFF list Password generatorRandom characters, exact entropy PIN generatorRandom digits, obvious PINs avoided Strength checkerAn estimate that shows its working Crack-time calculatorWhat bits mean in guesses and time The EFF wordlistAll 7,776 words, with a dice lookup

Already have a password?

The strength checker estimates how quickly a typed password would fall, and shows its working: common-list matches, dictionary words, keyboard walks, dates and repeats, each with its cost in bits. It runs in your browser and never sends what you type.

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Guides

Calm, sourced explanations of how passwords, passphrases and their alternatives work.

Making strong secrets

Making strong secretsHow passphrases workA passphrase is several words chosen at random from a known list. Its strength comes from the size of the list and the number of words, not from the words being secret.5 min read Making strong secretsPassword entropy, explained in bitsEntropy counts how many equally likely secrets a method could have produced, in powers of two. It is exact for random generators and only a rough guess for anything a person picked.4 min read Making strong secretsWhy length beats complexityEach added character multiplies the search space; each added character class only widens it a little. NIST's 2025 guidance sets a 15-character minimum and bans composition rules.4 min read

How passwords are attacked

How passwords are attackedHow data breaches expose passwordsA leaked database is not automatically a list of passwords. How the site stored them decides how much work an attacker faces.5 min read How passwords are attackedPassword hashing explained: salts and cost factorsPassword hashing turns a password into a stored value that is cheap to check once and expensive to check billions of times. Salts and cost factors are how.5 min read How passwords are attackedHow long does it take to crack a password?A crack time is just the size of the search divided by the guess rate. The hard parts are knowing the rate and knowing the real size of the search.5 min read

Beyond the password

Beyond the passwordHow password managers workA vendor-neutral look inside password managers: the encrypted vault, the master password, autofill by domain, sync, and what can still go wrong.6 min read Beyond the passwordTwo-factor authentication explainedThe factors, the common second-factor methods side by side, and why a code you type can be relayed by a phishing page while a security key cannot.5 min read Beyond the passwordHow authenticator apps make 6-digit codesStep by step through TOTP (RFC 6238) and HOTP (RFC 4226): the shared secret, the 30-second counter, the HMAC, the truncation, and an official test vector.5 min read

Under the hood

Under the hoodHow password generators workInside a password generator: why it must use the browser's CSPRNG and not Math.random, how it picks characters fairly, and how settings turn into bits.5 min read Under the hoodModulo bias and rejection sampling, worked throughA small arithmetic trap in password generators, worked through with real numbers: where the bias comes from, how big it is, and how to remove it.5 min read Under the hoodCharacter sets, look-alikes and Unicode in passwordsThe character sets behind password strength figures, the real cost of leaving out confusable characters, and why accented letters can break a login.5 min read

All 30 guides