1. What is Password Entropy?

Password entropy measures the unpredictability of a password based on the character set size and password length. It's expressed in bits and indicates how difficult a password is to crack through brute-force methods.

2. How Does the Calculator Work?

The calculator uses the password entropy equation:

Where:

• \( E \) — Password entropy in bits
• \( R \) — Size of the character set
• \( L \) — Length of the password

Explanation: The equation calculates how many bits of information are needed to represent all possible password combinations.

3. Importance of Password Entropy

Details: Higher entropy passwords are more secure against brute-force attacks. A password with 80+ bits of entropy is generally considered strong for most purposes.

4. Using the Calculator

Tips: Enter the size of your character set (e.g., 26 for lowercase letters only, 62 for alphanumeric) and your password length. Both values must be positive integers.

5. Frequently Asked Questions (FAQ)

Q1: What's a good entropy value for passwords?
A: For most purposes, aim for at least 80 bits of entropy. High-security systems may require 128+ bits.

Q2: How do I determine my character set size?
A: Count all possible characters: lowercase (26), uppercase (26), digits (10), and special characters (typically 30-40).

Q3: Does this account for dictionary attacks?
A: No, entropy only measures resistance to brute-force attacks. Dictionary attacks can crack low-entropy passwords more easily.

Q4: Why use log base 2?
A: Bits are the standard unit for information entropy, and log base 2 gives the number of bits needed to represent the information.

Q5: How does password length affect entropy?
A: Entropy increases linearly with length but exponentially with character set size, making length crucial for security.