There are tons of websites with weak authentication systems. Don't build such a site.
Re-implementing a new authentication system for every PHP project is not a good idea.
Building your own authentication classes piece by piece, and copying it to every project, is not recommended, either.
A secure authentication system with an easy-to-use API should be thoroughly designed and planned.
Peer-review for your critical infrastructure is a must.

Requirements

PHP 5.5.0+
- PDO
- OpenSSL

Installation

Set up the PHP library
- Install via Composer (recommended)
  
  $ composer require delight-im/auth
  
  Include the Composer autoloader:
  
  require __DIR__.'/vendor/autoload.php';
- or
- Install manually
  - Copy the contents of the src directory to a subfolder of your project
  - Include the files in your code via require or require_once
Set up a database and create the required tables
- MySQL

Usage

Create a new instance

// $db = new PDO('mysql:dbname=database;host=localhost;charset=utf8', 'username', 'password');
// $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

$auth = new Delight\Auth\Auth($db);

If you have an open PDO connection already, just re-use it.

try {
    $userId = $auth->register($_POST['email'], $_POST['password'], $_POST['username'], function ($selector, $token) {
        // send `$selector` and `$token` to the user (e.g. via email)
    });

    // we have signed up a new user with the ID `$userId`
}
catch (Delight\Auth\InvalidEmailException $e) {
    // invalid email address
}
catch (Delight\Auth\InvalidPasswordException $e) {
    // invalid password
}
catch (Delight\Auth\UserAlreadyExistsException $e) {
    // user already exists
}
catch (Delight\Auth\TooManyRequestsException $e) {
    // too many requests
}

For email verification, you should build an URL with the selector and token and send it to the user, e.g.:

$url = 'https://www.example.com/verify_email?selector='.urlencode($selector).'&token='.urlencode($token);

If you don't want to perform email verification, just omit the last parameter to register(...). The new user will be active immediately, then.

try {
    $auth->login($_POST['email'], $_POST['password'], ($_POST['remember'] == 1));

    // user is logged in
}
catch (Delight\Auth\InvalidEmailException $e) {
    // wrong email address
}
catch (Delight\Auth\InvalidPasswordException $e) {
    // wrong password
}
catch (Delight\Auth\EmailNotVerifiedException $e) {
    // email not verified
}
catch (Delight\Auth\TooManyRequestsException $e) {
    // too many requests
}

Perform email verification

Extract the selector and token from the URL that the user clicked on in the verification email.

try {
    $auth->confirmEmail($_GET['selector'], $_GET['token']);

    // email address has been verified
}
catch (Delight\Auth\InvalidSelectorTokenPairException $e) {
    // invalid token
}
catch (Delight\Auth\TokenExpiredException $e) {
    // token expired
}
catch (Delight\Auth\TooManyRequestsException $e) {
    // too many requests
}

Change the current user's password

If a user is currently logged in, they may change their password.

try {
    $auth->changePassword($_POST['oldPassword'], $_POST['newPassword']);

    // password has been changed
}
catch (Delight\Auth\NotLoggedInException $e) {
    // not logged in
}
catch (Delight\Auth\InvalidPasswordException $e) {
    // invalid password(s)
}

Logout

$auth->logout();

// user has been signed out

Features

registration
- secure password storage using the bcrypt algorithm
- email verification through message with confirmation link
- assurance of unique email addresses
- customizable password requirements and enforcement
- optional usernames with customizable restrictions
login
- keeping the user logged in for a long time via secure long-lived token ("remember me")
account management
- change password
- tracking the time of sign up and last login
- check if user has been logged in via "remember me" cookie
logout
- full and reliable destruction of session
session management
- protection against session fixation attacks
throttling
- per IP address
- per account
enhanced HTTP security
- prevents clickjacking
- prevent content sniffing (MIME sniffing)
- disables caching of potentially sensitive data

Exceptions

This library throws two types of exceptions to indicate problems:

AuthException and its subclasses are thrown whenever a method does not complete successfully. You should always catch these exceptions as they carry the normal error responses that you must react to.
AuthError and its subclasses are thrown whenever there is an internal problem or the library has not been installed correctly. You should not catch these exceptions.

General advice

Both serving the authentication pages (e.g. login and registration) and submitting the data entered by the user should only be done over TLS (HTTPS).
You should enforce a minimum length for passwords, e.g. 10 characters, but no maximum length. Moreover, you should not restrict the set of allowed characters.
Whenever a user was remembered ("remember me") and did not log in by entering their password, you should require re-authentication for critical features.
Encourage users to use passphrases, i.e. combinations of words or even full sentences, instead of single passwords.
Do not prevent users' password managers from working correctly. Thus please use the standard form fields only and do not prevent copy and paste.
Before executing sensitive account operations (e.g. changing a user's email address, deleting a user's account), you should always require re-authentication, i.e. require the user to sign in once more.
You should not offer an online password reset feature ("forgot password") for high-security applications.
For high-security applications, you should not use email addresses as identifiers. Instead, choose identifiers that are specific to the application and secret, e.g. an internal customer number.

Contributing

All contributions are welcome! If you wish to contribute, please create an issue first so that your feature, problem or question can be discussed.

License

Copyright 2015 delight.im <info@delight.im>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

  http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

README.md

Auth

Why do I need this?