Password Strength Checker

Entropy measures password unpredictability in bits. Higher = stronger. Calculation: bits = log2(possible_combinations). Example: 8 lowercase letters = 37 bits (weak), 16 mixed characters = 95 bits (strong). 60+ bits = resistant to offline attacks, 80+ bits = excellent. Character variety matters: adding numbers/symbols increases entropy exponentially. Use entropy to compare password strength objectively.

Depends on: password length, character variety, attacker resources. Online attacks (slow): 1000 tries/sec - weak passwords cracked in seconds. Offline attacks (fast): 100 billion tries/sec (GPUs) - 8 char password cracked in hours. Quantum computers (future threat). Defense: 16+ character passwords take centuries to crack offline. Use multi-factor authentication (MFA) - even cracked password cannot access account alone.

Yes, but length matters more. Special characters increase entropy slightly. 16 character lowercase > 10 character with symbols. Best: combine both. Use special characters naturally: "Blue$Sky&Morning27" vs "p@ssw0rd" (weak despite symbols). Avoid predictable substitutions (@ for a, 0 for o). Focus on length first, variety second. Passphrases with spaces/punctuation are ideal.

Check using Have I Been Pwned (HIBP) Pwned Passwords database (850M+ breached passwords). HIBP uses k-anonymity - sends only first 5 hash characters, checks locally. Our tool integrates HIBP API. If found: change immediately, enable MFA, check for unauthorized access. Breached passwords are targeted in credential stuffing attacks. Never reuse passwords across accounts.

Yes. Password managers are safer than reusing weak passwords. They generate strong unique passwords, store encrypted (AES-256), sync across devices, auto-fill securely. Recommended: Bitwarden (open-source), 1Password, LastPass, Dashlane. Use strong master password + MFA. Risk: single point of failure if master password compromised. Benefit: eliminates password reuse, phishing-resistant, convenience. Essential security tool.

Common mistakes: using personal info (names, birthdays), dictionary words (password, admin), patterns (123456, qwerty), password reuse across accounts, short passwords (<12 chars), predictable substitutions (p@ssw0rd), writing passwords down insecurely, sharing passwords, no MFA. Attackers exploit these patterns. Solution: password manager + unique passwords + MFA for all accounts. Change default passwords immediately.

Change only when: confirmed breach, suspected compromise, sharing password (stop sharing), weak password needs upgrade. Do not change routinely (causes weaker passwords). NIST (2024) recommends: no mandatory periodic changes, change only after breach, use long unique passwords + MFA. Exception: rotate privileged access credentials (90 days). Focus on breach monitoring, not arbitrary schedules.