Password Strength Analyzer & Checker

Password entropy measures the randomness of a password in bits. It is calculated as log2(pool_size ^ length), where pool_size is the number of possible characters. Higher entropy means more possible combinations an attacker must try. A password with 40 bits of entropy has about 1 trillion combinations, while 80 bits has over a sextillion — making brute force impractical.

Attackers maintain lists of the most commonly used passwords and their l33t speak variations. P@ssw0rd appears in virtually every password dictionary, so it would be cracked in seconds regardless of its character diversity. Pattern-based attacks check known substitutions (@ for a, 0 for o, 3 for e) before brute force.

For passwords protected by modern slow hashing algorithms like bcrypt, 12-16 characters with mixed character types provides strong protection. For systems using fast hashes like MD5 or SHA-1, longer passwords (16-20+) are needed. Passphrases of 4-5 random words (20-30 characters) offer both security and memorability.

A keyboard walk is a password created by pressing adjacent keys in sequence, like qwerty, asdfgh, or zxcvbn. These patterns feel random to users but are well-known to attackers. Password cracking tools include keyboard walk dictionaries that test these patterns early in an attack, making them far weaker than their length suggests.