How to Generate a Password That's Actually Secure

Most advice about "strong passwords" focuses on the wrong variable. Length, not complexity, is what actually determines how hard a password is to guess, and the difference isn't small.

What entropy actually measures

A password's strength is usually described in terms of entropy: roughly, how many attempts an attacker would need to guess it, expressed as a power of two. Every character position that could be any of, say, 26 lowercase letters contributes about 4.7 bits of entropy. A position that could be any of 94 possible characters (upper, lower, digits, symbols) contributes about 6.6 bits.

That's a real difference per character, but it's dwarfed by what adding more characters does, since entropy adds up per position:

• An 8-character password using all 94 characters: roughly 52 bits of entropy.
• A 16-character password using only lowercase letters: roughly 75 bits of entropy.

The second one is meaningfully stronger despite using a far smaller character set, purely because it's twice as long. This is why "use a passphrase of several random words" has become common security advice: four or five random dictionary words strung together easily clears 60-70 bits of entropy while staying easy to actually type and remember, something a P@ssw0rd!23-style password rarely achieves once you account for how predictable those substitutions are.

Password Generator generates randomness using the browser's own cryptographic RNG (the Web Crypto API), not a simple pseudo-random function, and lets you pick length and which character sets to include. Given the entropy math above, the single highest-leverage setting is length: push it up before worrying about which symbol sets are checked.

Why human-made passwords underperform their apparent complexity

A password like Tr0ub4dor&3 looks complex, but password-cracking tools don't guess character-by-character at random, they guess in order of likelihood, and that specific style of substitution (o to 0, a to 4, adding a symbol and digit at the end) is common enough to be one of the first patterns tried. The same is true of using a real word with the first letter capitalized, or a birth year appended.

A generator sidesteps this entirely by not following any pattern a human would recognize or default to. Every character is chosen independently, which means there's no shortcut for a cracking tool to exploit beyond trying every combination, exactly what the entropy calculation above assumes.

Where a hash fits in (and where it doesn't)

A hash is a different thing from a password, and confusing the two is a common source of misunderstanding. A hash is a one-way transformation: feed it any input and it produces a fixed-length fingerprint, but there's no way to run it backward to recover the original input. This is exactly why services store a hash of your password instead of the password itself, so that even if their database leaks, what leaks is the hash, not something an attacker can directly log in with.

Hash Generator computes SHA-1, SHA-256, SHA-384, and SHA-512 hashes of text or a file using the browser's built-in Web Crypto API. It's useful for verifying a file wasn't corrupted or tampered with (comparing its hash against a published one), or for generating a fingerprint of some text, but it isn't a password manager or a way to "encrypt" a password for later retrieval. A hash can't be decrypted back into the original text by design.

Where a UUID fits in (and why it's not a secret)

A UUID (universally unique identifier) is also easy to lump in with passwords and hashes, since all three are strings of random-looking characters. But a UUID isn't secret and isn't meant to be. It exists purely to be a unique label, for a database row, a session, a file, anything that needs an identifier unlikely to collide with any other identifier ever generated. UUID Generator generates random v4 UUIDs, which get their uniqueness from having enough random bits that a collision is astronomically unlikely, not from being kept secret. It's completely fine for a UUID to appear in a URL or a log file; the same is never true of a password.

Practical takeaways

• Favor length over complexity. A longer password with a smaller character set often beats a shorter one with every symbol type enabled.
• Use a generator, not a pattern. Predictable substitutions (o→0, a→@) are exactly what cracking tools check first.
• Don't reuse passwords across sites. Even a strong password only protects you until one site it's used on gets breached; a password manager makes generating and storing a unique one per site painless.
• Know the difference between a password, a hash, and a UUID. Only one of the three is a secret you need to protect.

The short version

A password's strength comes overwhelmingly from its length, not from cramming in symbols, and a randomly generated password beats a human-invented one because it has no exploitable pattern. Hashes and UUIDs are useful, related tools, but neither is a substitute for an actual password: a hash verifies without storing the secret, and a UUID was never a secret to begin with.