bit-entropy

Canonical URL:
https://alexstevovich.com/a/bit-entropy-nodejs

Software URL:
https://midnightcitylights.com/software/bit-entropy-nodejs

A utility to calculate the bit-level entropy of a string or identifier space based on its cardinality (number of unique symbols) and length.

This utility is based on information theory and provides a quick way to calculate the amount of information (in bits) that can be encoded using a string of a given length over a finite character set.

Installation

npm install bit-entropy

Example

import { bitEntropy } from 'bit-entropy';

console.log(bitEntropy(2, 8)); // 8 bits (e.g., binary byte)
console.log(bitEntropy(16, 32)); // 128 bits (e.g., UUID v4)
console.log(bitEntropy(62, 10)); // ~59.5 bits (Base62 string of length 10)

API

bitEntropy(cardinality, length)

Calculates the entropy in bits of a string or ID space.

Parameters:

• cardinality (number): The number of unique symbols in the character set (e.g., 62 for Base62).
• length (number): The length of the string or identifier.

Returns:

• number: The total entropy in bits.

Notes

• Cardinality refers to the number of unique symbols available (e.g., 62 for Base62 encoding).
• Length refers to the length of the string or identifier.
• This utility is based on the formula: entropy = length * log2(cardinality).

License

Licensed under the Apache License 2.0.