information-entropy

Calculate the required length or the entropy of a password. Inspired by the following Wikipedia article on password strength.

The result of these calculations assumes that the password generator uses a truly random selection process, where each symbol is randomly drawn from the set.

usage

const { calculateEntropy, calculateLength } = require(`information-entropy`)

const symbolSets = {
  hexadecimalNumerals: 16,
  asciiPrintableCharacters: 95,
  custom: [ `a`, `b`, 2 ]
}

const passwordLength = 24
calculateEntropy(symbolSet.hexadecimalNumerals, passwordLength)
// 96

const entropy = 128
calculateLength(symbolSet.asciiPrintableCharacters, entropy)
// 20
calculateLength(customSymbolSet, entropy)
// 81

api

calculateEntropy(symbolSet, passwordLength)

Returns the entropy in bits.

symbolSet and passwordLength can be anything with a .length property or a number denoting a length.

calculateLength(symbolSet, bitsOfEntropy)

Returns the required number of random selections from the set.

symbolSet can be anything with a .length property or a number denoting a size. bitsOfEntropy must be a number.