Introduction
In xkcd 936, Randall Munroe pointed out that "correct horse battery staple" is easier to remember than "Tr0ub4dor&3" and has more entropy. That comic changed how security engineers think about passwords. The insight: humans remember words, not random characters. A passphrase of 4-6 common words provides 51-77 bits of entropy while being genuinely memorable. Our Passphrase Generator uses the EFF large wordlist (7,776 words) with crypto.getRandomValues to produce Diceware-style passphrases that are both strong and easy to type.
What this tool does
- Generates passphrases from the EFF large wordlist (7,776 words) using cryptographic randomness.
- Configurable word count from 2 to 10 words with live entropy display.
- Choose separator: hyphen, space, underscore, dot, or none.
- Optionally capitalize each word for readability.
- Optionally append a random number to one word for systems that require digits.
How this tool works
The generator picks each word by drawing a random 32-bit integer from crypto.getRandomValues and mapping it to the EFF wordlist via modulo. The EFF wordlist was published in 2016 as a replacement for the original Diceware list (created by Arnold Reinhold in 1995). The EFF list was designed to be memorable, unambiguous, and free of offensive words. Each word contributes log2(7776) = ~12.9 bits of entropy. A 4-word passphrase has ~52 bits; a 6-word passphrase has ~77 bits. The separator and capitalization do not affect entropy but may affect system compatibility.
How Diceware passphrases work
Diceware was invented by Arnold Reinhold in 1995. The original method uses physical dice: you roll five six-sided dice to get a number from 11111 to 66666, then look up the corresponding word in a wordlist. Five dice rolls produce 6^5 = 7,776 possible words, which is why the standard Diceware wordlist has exactly 7,776 entries.
The EFF replaced the physical dice with a computer CSPRNG, but the math is the same. Each word selected uniformly at random from the 7,776-word list contributes:
log2(7776) = 12.925 bits
| Words | Entropy | Equivalent random password | |---|---|---| | 4 | ~52 bits | 8-char alphanumeric | | 5 | ~65 bits | 10-char alphanumeric | | 6 | ~77 bits | 12-char alphanumeric | | 7 | ~90 bits | 14-char alphanumeric |
The advantage over random passwords is memorability. "staple-horse-correct-battery" is easy to visualize and type. "K7mR9xVp" is not. The disadvantage is length: a 4-word passphrase is 20-30 characters, which some systems reject due to length limits.
NIST SP 800-63B explicitly endorses passphrases: "Users should be encouraged to make their passwords as long as they want, using any characters they like (including spaces), which can result in very long and memorable passphrases."
How to use this tool
- Set the word count. Four words is the minimum for decent security; six is recommended for high-value accounts.
- Choose a separator. Hyphens are common, but some systems require no separators.
- Toggle capitalization and number insertion based on your target system's requirements.
- Read the entropy estimate to verify the strength matches your needs.
- Click Generate New Passphrase and copy the result. Store it in a password manager.
Real-world examples
Password manager master password
A user sets up Bitwarden and needs a master password they can memorize. They generate a 6-word passphrase: "Velvet-Ocean-Prism-Tundra-Wisdom-Cactus7". At ~77 bits of entropy, it is computationally infeasible to brute-force, yet they can memorize it by visualizing the four objects. They write it down on paper stored in a safe as a backup.
WiFi network password
A network admin sets a WPA3 password for an office WiFi network. They generate a 4-word passphrase with spaces: "crystal meadow lantern whisper". It is easy to read aloud to visitors and type into phones. At ~52 bits, it exceeds WPA3's minimum security requirements for a passphrase that is also shared verbally.
Disk encryption passphrase
A journalist encrypts their laptop with LUKS. They need a passphrase that is strong enough to resist offline brute-force if the laptop is seized, but memorable enough to type daily. They choose 7 words with hyphens: "summit-river-beacon-harbor-quartz-ember-falcon". At ~90 bits, it would take billions of years to crack with current hardware.
Comparison with similar methods
| Method | Complexity | Typical use |
|---|---|---|
| Diceware passphrase (EFF list) | Low | Memorable high-entropy passwords for daily use |
| Random character password | Low | Maximum entropy per character, stored in a manager |
| Human-chosen passphrase | Low | Convenient but prone to word selection bias |
Limitations or considerations
Passphrases are longer than character-based passwords, which some systems reject. If a service caps password length at 20 characters, a 4-word passphrase with hyphens may exceed the limit. The EFF wordlist uses only English words; non-English speakers may find them harder to memorize. The entropy estimate assumes uniform random selection, which holds true only because the generator uses crypto.getRandomValues. Do not pick words yourself; humans introduce bias that reduces effective entropy.
Frequently asked questions
How many words should I use?
Four words (~52 bits) is the minimum for most accounts. Use six words (~77 bits) for high-value targets like password manager master passwords or disk encryption.
Are passphrases better than random passwords?
They are easier to memorize for the same entropy. For passwords stored in a manager, random passwords are more compact. For passwords you must memorize, passphrases win.
What is the EFF wordlist?
A list of 7,776 words published by the Electronic Frontier Foundation in 2016 as a modern replacement for the original Diceware list. It avoids obscure, offensive, and ambiguous words.
Can attackers guess passphrases with dictionary attacks?
No, because the search space is 7776^n where n is the word count. A 4-word passphrase has 3.6 x 10^15 combinations. Dictionary attacks work against human-chosen words, not random selection.
Should I add a number or symbol?
Only if the target system requires it. A random number appended to one word adds ~3.3 bits, which is marginal. Adding more words is more effective.
Conclusion
Passphrases solve the real password problem: memorability without sacrificing security. Generate one with 6+ words for your password manager master password or disk encryption key. For service passwords you store in a manager, use the Password Generator instead. Check your passphrase strength with the Password Strength Checker.