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index.js
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index.js
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// Copyright 2015-2017 Parity Technologies (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
const dictionary = require('./res/wordlist.json')
function isDefined (str) {
return str !== 'undefined'
}
// Adapted from https://github.com/tonyg/js-scrypt
// js-scrypt is written by Tony Garnock-Jones tonygarnockjones@gmail.com and is licensed under the 2-clause BSD license:
function secureRandomBytes (count) {
if (!isDefined(typeof Uint8Array)) {
return null
}
const bs = new Uint8Array(count)
const self = isDefined(typeof window) ? window : isDefined(typeof global) ? global : this
if (isDefined(typeof self.crypto)) {
if (isDefined(typeof self.crypto.getRandomValues)) {
self.crypto.getRandomValues(bs)
return bs
}
}
if (isDefined(typeof self.msCrypto)) {
if (isDefined(typeof self.msCrypto.getRandomValues)) {
self.msCrypto.getRandomValues(bs)
return bs
}
}
return null
}
function randomBytes (length) {
const random = secureRandomBytes(length)
if (random) {
return random
}
// Fallback if secure randomness is not available
const buf = isDefined(typeof Buffer) ? Buffer.alloc(length) : Array(length)
for (let i = 0; i < length; i++) {
buf[i] = Math.random() * 255
}
return buf
}
function randomNumber (max) {
// Use 24 bits to avoid the integer becoming signed via bitshifts
const rand = randomBytes(3)
const integer = (rand[0] << 16) | (rand[1] << 8) | rand[2]
// floor to integer value via bitor 0
return ((integer / 0xFFFFFF) * max) | 0
}
function randomWord () {
// TODO mh: use better entropy
const index = randomNumber(dictionary.length)
return dictionary[index]
}
function randomPhrase (length) {
const words = []
while (length--) {
words.push(randomWord())
}
return words.join(' ')
}
let dictionaryLookup = null
function verifyPhrase (phrase, expectedLength) {
if (!dictionaryLookup) {
dictionaryLookup = {}
dictionary.forEach(word => {
dictionaryLookup[word] = true
})
}
const words = phrase.split(/\s+/)
const wrongWord = words.find(word => !dictionaryLookup[word])
if (wrongWord) {
throw new Error(`Word is not in the dictionary: ${wrongWord}.`)
}
if (words.length < expectedLength) {
throw new Error(`Phrase is too short: ${words.length}.`)
}
return true
}
module.exports = {
randomBytes,
randomNumber,
randomWord,
randomPhrase,
verifyPhrase
}