Source code

Revision control

Other Tools

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
/**
* This file is a port of a subset of Chromium's implementation from
* which is Copyright 2018 The Chromium Authors. All rights reserved.
*/
const EXPORTED_SYMBOLS = ["PasswordGenerator"];
const { XPCOMUtils } = ChromeUtils.import(
);
XPCOMUtils.defineLazyGlobalGetters(this, ["crypto"]);
const DEFAULT_PASSWORD_LENGTH = 15;
const MAX_UINT8 = Math.pow(2, 8) - 1;
const MAX_UINT32 = Math.pow(2, 32) - 1;
// Some characters are removed due to visual similarity:
const LOWER_CASE_ALPHA = "abcdefghijkmnpqrstuvwxyz"; // no 'l' or 'o'
const UPPER_CASE_ALPHA = "ABCDEFGHJKLMNPQRSTUVWXYZ"; // no 'I' or 'O'
const DIGITS = "23456789"; // no '1' or '0'
const ALL_CHARACTERS = LOWER_CASE_ALPHA + UPPER_CASE_ALPHA + DIGITS;
const REQUIRED_CHARACTER_CLASSES = [LOWER_CASE_ALPHA, UPPER_CASE_ALPHA, DIGITS];
this.PasswordGenerator = {
/**
* @param {Number} length of the password to generate
* @returns {string} password that was generated
* @throws Error if `length` is invalid
* @copyright 2018 The Chromium Authors. All rights reserved.
*/
generatePassword(length = DEFAULT_PASSWORD_LENGTH) {
if (length < REQUIRED_CHARACTER_CLASSES.length) {
throw new Error("requested password length is too short");
}
if (length > MAX_UINT8) {
throw new Error("requested password length is too long");
}
let password = "";
// Generate one of each required class
for (const charClassString of REQUIRED_CHARACTER_CLASSES) {
password +=
charClassString[this._randomUInt8Index(charClassString.length)];
}
// Now fill the rest of the password with random characters.
while (password.length < length) {
password += ALL_CHARACTERS[this._randomUInt8Index(ALL_CHARACTERS.length)];
}
// So far the password contains the minimally required characters at the
// the beginning. Therefore, we create a random permutation.
password = this._shuffleString(password);
return password;
},
/**
* @param range to generate the number in
* @returns a random number in range [0, range).
* @copyright 2018 The Chromium Authors. All rights reserved.
*/
_randomUInt8Index(range) {
if (range > MAX_UINT8) {
throw new Error("`range` cannot fit into uint8");
}
// We must discard random results above this number, as they would
// make the random generator non-uniform (consider e.g. if
// MAX_UINT64 was 7 and |range| was 5, then a result of 1 would be twice
// as likely as a result of 3 or 4).
const MAX_ACCEPTABLE_VALUE = Math.floor(MAX_UINT8 / range) * range - 1;
const randomValueArr = new Uint8Array(1);
do {
crypto.getRandomValues(randomValueArr);
} while (randomValueArr[0] > MAX_ACCEPTABLE_VALUE);
return randomValueArr[0] % range;
},
/**
* Shuffle the order of characters in a string.
* @param {string} str to shuffle
* @returns {string} shuffled string
*/
_shuffleString(str) {
let arr = Array.from(str);
// Generate all the random numbers that will be needed.
const randomValues = new Uint32Array(arr.length - 1);
crypto.getRandomValues(randomValues);
// Fisher-Yates Shuffle
for (let i = arr.length - 1; i > 0; i--) {
const j = Math.floor((randomValues[i - 1] / MAX_UINT32) * (i + 1));
[arr[i], arr[j]] = [arr[j], arr[i]];
}
return arr.join("");
},
};