eff-diceware-passphrase

Generate a cryptographically random password from EFF's improved Diceware word list

In July 2016, EFF release a more user friendly Diceware list in the article Deep Dive: EFF's New Wordlists for Random Passphrases.

A Diceware list is a dictionary of 6^5 == 7776 words, making it possible to use 5 normal dice as a source of entropy. Since the dictionary is fixed, it is possible to reason about how much entropy each new word (token) contributes to the passphrase; lg(6^5) ≈ 12.9 bits.

However in this module we use the CSRNG builtin to sample n words from the dictionary, and securely shuffle them. The sampling is without replacement as to not confuse the user in case of repeated words. This lowers the entropy by a negligible amount.

Usage

var generatePassphrase = require('eff-diceware-passphrase')

generatePassphrase(8) // List of 8 words
generatePassphrase.entropy(100) // List of words with at least 100 bits of entropy

You can also get the JSON encoded dictionary directly:

var dictionary = require('eff-diceware-passphrase/wordlist.json')

Bundle size considerations

Be aware that the JSON encoded Diceware list is just over 25kb gzipped. Making a minimal Browserify bundle with optimisations will yield a bundle of 34.6kb.

$ browserify -g uglifyify -g unassertify example.js | uglifyjs -cm | gzip - | wc -c
34593

API

generatePassphrase(count)

Generate a list of count words, randomly shuffled and without replacement.

const arr = generatePassphrase.words

Sorted array of all words in the Diceware list

const arr = generatePassphrase.entropy(minimum)

Convenience function for generating a password with at least mimimum bits of entropy.

const i = generatePassphrase.indexOf(word)

Like Array.prototype.indexOf. Returns the index in generatePassphrase.words or -1 if not found.

const bool = generatePassphrase.includes(word)

Like Array.prototype.includes. Returns true if part of generatePassphrase.words or false if not found.

const i = generatePassphrase.indexOfPrefix(prefix)

Returns the index of the first occurrence of the prefix, or the end of the wordlist if no prefixes match. Can be used to slice the list for eg. autocomplete

Install

npm install eff-diceware-passphrase

License

ISC