Password Strength Checker

Password strength is measured in bits of entropy — the logarithm (base 2) of the total number of possible passwords given its character set and length. A password using 26 lowercase letters and 10 digits (36 possible characters) with length 12 has log2(36^12) ≈ 62 bits of entropy.

General thresholds: under 28 bits is trivially crackable, 28-35 bits is weak, 36-59 is fair, 60-127 is strong, and 128+ bits is considered beyond brute-force reach with current technology. But entropy alone isn't everything — patterns like dictionary words, keyboard sequences (qwerty), and repeated characters drastically reduce effective strength.

This tool goes beyond simple entropy calculation. It checks for common passwords (the "password123" problem), sequential patterns, character repetition, and character set diversity. The estimated crack time assumes an offline attack at 10 billion guesses per second — representative of a GPU-accelerated hash cracking setup.