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Password Strength Analyzer
The ultimate tool for digital identity protection. Test your credentials against billions of known leaks, calculate precise entropy bits, and audit for NIST 2025 compliance.
Password Strength Analyzer
Analyze entropy, crack time, and security score locally.
Strength: Enter PasswordScore: 0/4
What is Password Strength Analyzer?
The **Password Strength Analyzer** is an enterprise-grade security tool designed for developers, sysadmins, and security-conscious users. Unlike basic checkers that simply count characters, this tool uses the **zxcvbn** engine (Dropbox) and **NIST Special Publication 800-63B** guidelines to evaluate true defensive strength. It detects patterns susceptible to dictionary attacks, estimates brute-force costs, and educates on the mathematics of entropy.
How to Use Password Strength Analyzer
1
**Enter Credential**: Type your password into the client-side secure input. Data *never* leaves your browser.
2
**Audit Entropy**: Review the 'Bits of Entropy' score. NIST recommends 80+ bits for user-generated secrets.
3
**Check Compliance**: Verify if your password meets modern 2025 standards (Length > Complexity).
4
**Analyze Vectors**: See estimated crack times for Online Throttled vs. Offline GPU Hashcat attacks.
Key Features
**NIST 2025 Compliant**: Evaluates passwords based on length and ban-lists rather than outdated complexity rules.
**Entropy Calculator**: Uses $E = L \times \log_2(R)$ to determine the exact theoretical hardness.
**Attack Simulation**: Estimates time-to-crack against specific hardware (e.g., RTX 4090 clusters).
**Pattern Detection**: Identifies 'Keyboard Walks' (qwerty), repeats, and leetspeak substitutions.
**Offline Security**: Zero-knowledge architecture. Works without an internet connection.
About Password Strength Analyzer
The Mathematics of Entropy
Password strength is scientifically measured in **Entropy Bits**. This quantifies the "randomness" or "surprise" a password contains. The formula is:
E = L × log₂(R)
- L (Length):Number of characters. This is the exponent, making it the most critical factor.
- R (Range):Pool of unique characters (e.g., 26 for lowercase, 94 for all ASCII).
Example: A 12-character lowercase password ($12 \times 4.7 \approx 56$ bits) is weaker than a 20-character lowercase passphrase ($20 \times 4.7 \approx 94$ bits), even without special symbols.
NIST Guidelines 2025 (SP 800-63B)
The National Institute of Standards and Technology (NIST) has overhauled password advice. The old advice ("change it every 90 days", "must use special chars") is now considered **harmful**.
Length Over Complexity
Humans are bad at random characters (we pick `P@ssw0rd!`). Length is mathematically superior. NIST recommends 8-64 characters.
No Mandatory Rotation
Forcing users to change passwords leads to `Pass1`, `Pass2`, `Pass3`. Only change passwords if compromised.
Full Unicode Support
Passwords should allow spaces and emojis (e.g., "correct horse battery staple 🐴").
Understanding Attack Vectors
Brute Force
Attacking by trying every combination (`aaaa`, `aaab`). Defeated by **High Entropy**.
Defense: Long passwords (16+ chars).
Rainbow Tables
Pre-computed tables of hashes for common passwords. Defeated by **Salting** (server-side) and **Uniqueness** (client-side).
Defense: Never reuse passwords.
Time to Crack Estimation
| Type | Length | Entropy | Crack Time (RTX 4090) |
|---|---|---|---|
| Numerical | 8 chars | ~26 bits | Instant |
| Lower + Upper | 8 chars | ~45 bits | 3 minutes |
| Complex | 12 chars | ~72 bits | 300 years |
| Passphrase | 20 chars | ~100 bits | 100 Trillion Years |
Frequently Asked Questions
Why doesn't NIST recommend special characters anymore?
Because users follow predictable patterns (e.g., 'Password123!'). It forces 'complexity' but not 'randomness'. Length is a much stronger mathematical defense against brute force than a limited set of special characters.
What is 80 bits of entropy?
It's the industry threshold for a 'Strong' password. 80 bits means there are $2^{80}$ possible combinations. Even with a supercomputer making trillions of guesses per second, it would take centuries to crack.
Is this tool safe? Does it send data?
Yes. This tool is **Client-Side Only**. The code runs in your browser's JavaScript engine. No data is sent over the network. You can disconnect your internet and the tool will still work perfectly.
What is a Dictionary Attack?
Instead of trying random characters (brute force), attackers try words from a dictionary (e.g., 'password', 'monkey', 'football'). Since humans often use real words, this method is extremely fast.
Should I use a Password Manager?
Absolutely. NIST strongly recommends them. They allow you to use unique, 20+ character random passwords for every site without needing to memorize them.