Passphrase Generator: Why 4 Random Words Beat P@$$w0rd

In 2011, a webcomic changed how the security world thinks about passwords.

Randall Munroe's XKCD #936 showed a simple truth: a passphrase like correct horse battery staple has more entropy and is far easier to remember than Tr0ub4dor&3. The math isn't even close.

Fifteen years later, the security community has caught up. NIST recommends long passwords over complex ones. Password managers support passphrases natively. And "make it long" has replaced "make it weird" as the golden rule.

Here's everything you need to know about passphrases — and how to generate one that's both memorable and uncrackable.

What Is a Passphrase?

A passphrase is a password made of multiple random words strung together, usually separated by hyphens or spaces:

• marble-sunset-keyboard-falcon
• correct horse battery staple
• timber.oxygen.candle.rhythm

The security comes from length and randomness, not from symbol substitutions or mixed case. Each additional random word multiplies the number of possible combinations exponentially.

The critical part? The words must be truly random — not a phrase you'd naturally say, not a song lyric, not a quote. "ilovemydogmax" is a passphrase, but it's a terrible one. "anvil-mercury-tundra-lemon" is the goal.

The XKCD Comic That Changed Everything

XKCD #936 compared two password strategies:

Strategy 1: Complex password Tr0ub4dor&3 — 11 characters, mixed case, symbols, numbers. Looks strong. But it's based on a dictionary word with common substitutions, so the actual entropy is about 28 bits. A cracker with a rule-based dictionary attack breaks it fast.

Strategy 2: Four random words correct horse battery staple — 28 characters, all lowercase. Looks simple. But choosing 4 words randomly from a 2,048-word list gives 44 bits of entropy. Much harder to crack, much easier to remember.

The comic's conclusion: "Through 20 years of effort, we've successfully trained everyone to use passwords that are hard for humans to remember, but easy for computers to guess."

That insight still holds.

Entropy: Why Passphrases Win the Math

Entropy measures how unpredictable a password is, expressed in bits. More bits = more secure.

Random Password Entropy

For a random password of length L using a character set of size S:

Entropy = L × log₂(S)

An 10-character password using 95 printable ASCII characters: 10 × 6.57 = 65.7 bits

Passphrase Entropy

For a passphrase of N random words from a wordlist of size W:

Entropy = N × log₂(W)

A 4-word passphrase from a 7,776-word diceware list: 4 × 12.9 = 51.7 bits

A 5-word passphrase: 5 × 12.9 = 64.6 bits

A 6-word passphrase: 6 × 12.9 = 77.5 bits

So a 6-word passphrase from a standard diceware list has more entropy than a 10-character random password — and it's something you can actually remember.

How Long Would It Take to Crack?

The key insight: a 6-word passphrase matches a 12-character random password in security — but one of them you can memorize in minutes, and the other you'll never type correctly.

The Diceware Method Explained

Diceware is the original passphrase generation method, created by Arnold Reinhold in 1995. It uses physical dice to ensure true randomness:

How it works:

1. Roll 5 dice (or one die 5 times) to get a 5-digit number
2. Look up the number in the Diceware word list (7,776 words total)
3. Repeat for each word you want (4-6 words recommended)
4. Combine the words into your passphrase

Example:

• Roll: 4-1-6-5-2 → molecular
• Roll: 2-3-4-5-1 → crash
• Roll: 5-5-1-3-6 → shawl
• Roll: 1-6-4-2-3 → bulky
• Passphrase: molecular-crash-shawl-bulky

The beauty of Diceware is that even if an attacker knows you used the method and knows the exact word list, they still can't crack it without trying all possible combinations. The randomness of the dice selection is what provides the security.

Don't have dice? Our passphrase generator uses a cryptographically secure random number generator to pick words — it's just as random, and faster.

Passphrase vs. Password: When to Use Each

Both have their place. Here's a practical decision guide:

Use a Passphrase When:

• You need to memorize it — your master password for a password manager
• You type it frequently — computer login, phone unlock, disk encryption
• The service allows long passwords — most modern services do
• You want something human-friendly — easier to share verbally if needed

Use a Random Password When:

• A password manager stores it — you'll never type it, so memorability doesn't matter
• The service has a character limit — some sites still cap at 16 or 20 characters
• You need maximum entropy per character — when every character counts
• The field doesn't support spaces — rare, but it happens

The hybrid approach: Use a passphrase as your password manager's master password, and let the manager generate random passwords for everything else. Best of both worlds.

How to Generate a Secure Passphrase

Option 1: Use Our Generator

Visit our passphrase generator — select the number of words, separator style, and whether to include a number for extra entropy. One click, done.

Option 2: Diceware (Physical Dice)

Roll actual dice and use the EFF Diceware word list. This guarantees no software was involved in the randomness, which some people prefer.

Option 3: Manually from a Wordlist

Open a word list, use a random number generator to pick word positions. Not recommended — it's tedious and humans tend to subconsciously avoid "weird" combinations, reducing randomness.

Tips for Better Passphrases:

• Use 5+ words for anything important (email, banking, master password)
• Add a random number or symbol between words for extra entropy: marble-7-sunset-keyboard-falcon
• Use hyphens or periods as separators — easier to type than spaces on mobile
• Don't modify words to make them "better" — that reduces randomness
• Don't reject and re-roll because the combination seems silly — silly is good

Common Passphrase Mistakes to Avoid

Even passphrases can be weak if you break the rules:

• ❌ Using a meaningful phrase: "i love my dog max" — this is a sentence, not a passphrase
• ❌ Picking words yourself: Humans aren't random. You'll gravitate toward associated words
• ❌ Using only 3 words: The minimum for any real security is 4 words, and 5+ is better
• ❌ Using a famous passphrase: Don't use "correct horse battery staple" — it's literally in cracking dictionaries now
• ❌ Reusing your passphrase: Same rules apply — unique per account

FAQ

How many words should a passphrase have?

For most purposes, 4-5 words is sufficient. For your most critical accounts (email, password manager master password, disk encryption), use 6+ words. Each additional word roughly doubles the time to crack.

Are passphrases really more secure than complex passwords?

When generated randomly, a 5-6 word passphrase has comparable or greater entropy than a 10-12 character random password. The advantage is that passphrases are dramatically easier to memorize, which means people actually use strong ones instead of falling back to "Password1!".

Can I add numbers or symbols to my passphrase?

Yes, and it helps. Adding a random digit between words or capitalizing one random letter adds extra entropy. Just don't do it in a predictable way (like always capitalizing the first letter of the first word).

What's the best wordlist to use?

The EFF Diceware wordlists are excellent — they use common, easy-to-spell English words. Our passphrase generator uses a curated list optimized for memorability and typing speed.

Why can't I just pick random words from a dictionary myself?

Because humans are bad at randomness. Studies show that when people "randomly" pick words, they tend toward common words, related concepts, and familiar patterns. True randomness requires a mechanical process — dice or a cryptographic random number generator.