Tiny password entropy calculator
For the jQuery plugin, click here
What is entropy and why should I care?
Entropy is a measure of disorder. In the context of passwords, it's a measure of how many different password combinations there are using a certain set of rules. The more combinations an attacker has to check, the longer it will take them to crack your password by brute force.
Entropy is expressed in bits - this is the logarithm (base 2) of the number of combinations. As such, an 80-bit password isn't twice as strong as a 40-bit password, it's 240 (about a trillion) times stronger.
A lot of password meters still use basic criteria such as minimum length, number and symbol requirements etc. This is inadequate and results in weak, forgettable passwords. Entropy is a much more reliable measure of password strength.
What is Entropizer?
Entropizer is a simple, super-lightweight (~1kb minified) library that calculates password entropy. It's easy to set up and customize, and comes with several preset character classes. You can also define custom character classes (e.g. for localization).
// Use default character classes: lowercase, uppercase, numeric, split symbols (common and uncommon)var entropizer = ;// ~57 bits of entropyvar entropy = entropizer;
Preset character classes are found under
Specify the classes to use:
// Using namesvar entropizer =classes: 'lowercase' 'uppercase' 'numeric';// Using the character class objectsvar entropizer =classes:EntropizerclasseslowercaseEntropizerclassesuppercaseEntropizerclassesnumeric;// Custom character classesvar entropizer =classes:regex: /[a-m]/ size: 13 // Using regex and a class sizecharacters: 'nopqrstuvwxyz' // Using characters (implicit size);
You can mix and match these different ways of defining character classes.
Read the source, it's tiny!