Password Entropy Checker
The Password Entropy Checker evaluates the mathematical strength of passwords offline. It calculates the Shannon entropy to estimate how many bits of information the password contains.
Syntax
Arguments
PASSWORD: The password string to evaluate (optional if using interactive mode).
Options
-i, --interactive: Prompt for the password securely (prevents the password from appearing in shell history).--help: Show this message and exit.
Usage Examples
Quick check
Secure interactive check (Recommended)
Understanding Entropy
Entropy is measured in bits. It represents the number of guesses required to crack a password in a worst-case brute-force scenario ($2^E$ guesses).
| Entropy | Strength |
|---|---|
| < 40 bits | Very Weak |
| 40-60 bits | Weak |
| 60-80 bits | Moderate |
| 80-100 bits | Strong |
| > 100 bits | Very Strong |
Technical Details
This tool uses the formula $E = L \times \log_2(R)$, where: - $L$ is the length of the password. - $R$ is the size of the character pool (charset) used in the password.
It automatically detects the charset size based on the presence of lowercase, uppercase, digits, and special characters.
[!IMPORTANT] This tool runs entirely offline. Your password is never sent to any server or API.