Password Generator

Password generation is one of the few security tasks where the tool matters as much as the intent. A long, random, unique password defeats essentially every credential attack that does not involve phishing or a breached database — and both of those are better solved by a password manager and two-factor authentication than by a cleverer password.

Where the randomness comes from

Math.random() in JavaScript is a pseudorandom number generator seeded from the system clock. It is fast, it passes casual statistical tests, and it is completely unsuitable for security: an attacker who observes enough output can recover the internal state and predict everything that follows.

crypto.getRandomValues() draws from the operating system's entropy pool — the same source used for TLS session keys and SSH key generation. It is not predictable, not reproducible and not observable from another origin. This tool uses it exclusively, and applies rejection sampling so that the modulo bias introduced by mapping random bytes onto a character set is eliminated rather than merely reduced.

Entropy, in numbers

bits = length × log2(poolSize)

The pattern worth noticing: moving from 12 to 16 characters gains more than adding every symbol on the keyboard to a 12-character password. Length is the dominant lever.

How passwords actually get attacked

Offline cracking. An attacker obtains a hash dump and tries candidates at billions per second on a GPU. This is where entropy matters most, and where short passwords fail catastrophically — a fast hash like MD5 or SHA-1 lets an 8-character mixed password fall in hours.

Credential stuffing. An attacker replays username-and-password pairs leaked from other breaches. Entropy is irrelevant; uniqueness is everything. This is why reusing a strong password is worse than using a mediocre unique one.

Phishing. The password is handed over voluntarily. Neither length nor complexity helps. A hardware security key or a passkey does.

Database compromise with correct hashing. If the service uses bcrypt, scrypt or Argon2 with proper parameters, offline cracking is expensive even for moderate passwords. If it uses SHA-256, a 40-character password may still fall.

Passphrases

The diceware approach picks N words at random from a numbered wordlist. With the standard 7776-word list, each word contributes log2(7776) ≈ 12.9 bits:

• 4 words ≈ 52 bits — too weak for anything important
• 5 words ≈ 65 bits — acceptable for low-value accounts
• 6 words ≈ 78 bits — good
• 7 words ≈ 90 bits — excellent, and still typeable

Word order matters, and so does randomness: choosing six words yourself produces dramatically less entropy than six words drawn by dice, because human word choice is highly predictable.

Practical advice

Generate unique passwords everywhere and store them in a password manager. Make the manager's own master key a long passphrase you can remember and never wrote down. Enable a second factor — preferably a passkey or hardware key, not SMS — on any account where losing access would hurt. Then stop thinking about passwords, which is the point of the exercise.