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 5.6.0+
- OpenSSL extension (openssl)
MySQL 5.5.3+ or MariaDB 5.5.23+

Installation

Include the library via Composer:
```
$ composer require delight-im/auth
```

Include the Composer autoloader:

require __DIR__ . '/vendor/autoload.php';

Set up a database and create the required tables:
- MySQL

Usage

Creating a new instance
Registration (sign up)
Login (sign in)
Email verification
Keeping the user logged in
Password reset ("forgot password")
Changing the current user's password
Logout
Accessing user information
Administration (managing users)
- Creating new users
Utilities
- Creating a random string
- Creating a UUID v4 as per RFC 4122
Reading and writing session data

Creating a new instance

// $db = new PDO('mysql:dbname=my-database;host=localhost;charset=utf8mb4', 'my-username', 'my-password');
// or
// $db = new \Delight\Db\PdoDsn('mysql:dbname=my-database;host=localhost;charset=utf8mb4', 'my-username', 'my-password');

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

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

If you do enforce HTTPS on your site, pass true as the second parameter to the constructor. This is optional and the default is false.

Only in the very rare case that you need access to your cookies from JavaScript, pass true as the third argument to the constructor. This is optional and the default is false. There is almost always a better solution than enabling this, however.

If your web server is behind a proxy server and $_SERVER['REMOTE_ADDR'] only contains the proxy's IP address, you must pass the user's real IP address to the constructor in the fourth argument. The default is null.

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
}

The username in the third parameter is optional. You can pass null there if you don't want to manage usernames.

If you want to enforce unique usernames, on the other hand, simply call registerWithUniqueUsername instead of register, and be prepared to catch the DuplicateUsernameException.

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 Auth#register. The new user will be active immediately, then.

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

    // 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
}

If you want to sign in with usernames on the other hand, either in addition to the login via email address or as a replacement, that's possible as well. Simply call the method loginWithUsername instead of method login. Then, instead of catching InvalidEmailException, make sure to catch both UnknownUsernameException and AmbiguousUsernameException. You may also want to read the notes about the uniqueness of usernames in the section that explains how to sign up new users.

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
}

Keeping the user logged in

The third parameter to the Auth#login method controls whether the login is persistent with a long-lived cookie. With such a persistent login, users may stay authenticated for a long time, even when the browser session has already been closed and the session cookies have expired. Typically, you'll want to keep the user logged in for weeks or months with this feature, which is known as "remember me" or "keep me logged in". Many users will find this more convenient, but it may be less secure if they leave their devices unattended.

if ($_POST['remember'] == 1) {
    // keep logged in for one year
    $rememberDuration = (int) (60 * 60 * 24 * 365.25);
}
else {
    // do not keep logged in after session ends
    $rememberDuration = null;
}

// ...

$auth->login($_POST['email'], $_POST['password'], $rememberDuration);

// ...

Without the persistent login, which is the default behavior, a user will only stay logged in until they close their browser, or as long as configured via session.cookie_lifetime and session.gc_maxlifetime in PHP.

Omit the third parameter or set it to null to disable the feature. Otherwise, you may ask the user whether they want to enable "remember me". This is usually done with a checkbox in your user interface. Use the input from that checkbox to decide between null and a pre-defined duration in seconds here, e.g. 60 * 60 * 24 * 365.25 for one year.

Password reset ("forgot password")

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

    // request has been generated
}
catch (\Delight\Auth\InvalidEmailException $e) {
    // invalid email address
}
catch (\Delight\Auth\EmailNotVerifiedException $e) {
    // email not verified
}
catch (\Delight\Auth\TooManyRequestsException $e) {
    // too many requests
}

You should build an URL with the selector and token and send it to the user, e.g.:

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

As the next step, users will click on the link that they received. Extract the selector and token from the URL.

If the selector/token pair is valid, let the user choose a new password:

if ($auth->canResetPassword($_POST['selector'], $_POST['token'])) {
    // put the selector into a `hidden` field (or keep it in the URL)
    // put the token into a `hidden` field (or keep it in the URL)

    // ask the user for their new password
}

Now when you have the new password for the user (and still have the other two pieces of information), you can reset the password:

try {
    $auth->resetPassword($_POST['selector'], $_POST['token'], $_POST['password']);

    // password has been reset
}
catch (\Delight\Auth\InvalidSelectorTokenPairException $e) {
    // invalid token
}
catch (\Delight\Auth\TokenExpiredException $e) {
    // token expired
}
catch (\Delight\Auth\InvalidPasswordException $e) {
    // invalid password
}
catch (\Delight\Auth\TooManyRequestsException $e) {
    // too many requests
}

Changing 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

Accessing user information

if ($auth->isLoggedIn()) {
    // user is signed in
}
else {
    // user is *not* signed in yet
}

A shorthand/alias for this method is $auth->check().

User ID

$id = $auth->getUserId();

If the user is not currently signed in, this returns null.

A shorthand/alias for this method is $auth->id().

Email address

$email = $auth->getEmail();

If the user is not currently signed in, this returns null.

Display name

$email = $auth->getUsername();

Remember that usernames are optional and there is only a username if you supplied it during registration.

If the user is not currently signed in, this returns null.

Checking whether the user was "remembered"

if ($auth->isRemembered()) {
    // user did not sign in but was logged in through their long-lived cookie
}
else {
    // user signed in manually
}

If the user is not currently signed in, this returns null.

IP address

$ip = $auth->getIpAddress();

Additional user information

In order to preserve this library's suitability for all purposes as well as its full re-usability, it doesn't come with additional bundled columns for user information. But you don't have to do without additional user information, of course:

Here's how to use this library with your own tables for custom user information in a maintainable and re-usable way:

Add any number of custom database tables where you store custom user information, e.g. a table named profiles.
Whenever you call the register method (which returns the new user's ID), add your own logic afterwards that fills your custom database tables.

If you need the custom user information only rarely, you may just retrieve it as needed. If you need it more frequently, however, you'd probably want to have it in your session data. The following method is how you can load and access your data in a reliable way:

function getUserInfo(\Delight\Auth\Auth $auth) {
    if (!$auth->isLoggedIn()) {
        return null;
    }

    if (!isset($_SESSION['_internal_user_info'])) {
        // TODO: load your custom user information and assign it to the session variable below
        // $_SESSION['_internal_user_info'] = ...
    }

    return $_SESSION['_internal_user_info'];
}

Administration (managing users)

The administrative interface is available via $auth->admin(). You can call various method on this interface, as documented below.

Warning: Do not forget to implement secure access control before exposing access to this interface. For example, you may provide access to this interface to logged in users with the administrator role only, or use the interface in private scripts only.

Creating new users

try {
    $userId = $auth->admin()->createUser($_POST['email'], $_POST['password'], $_POST['username']);

    // 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
}

The username in the third parameter is optional. You can pass null there if you don't want to manage usernames.

If you want to enforce unique usernames, on the other hand, simply call createUserWithUniqueUsername instead of createUser, and be prepared to catch the DuplicateUsernameException.

Utilities

Creating a random string

$length = 24;
$randomStr = \Delight\Auth\Auth::createRandomString($length);

Creating a UUID v4 as per RFC 4122

$uuid = \Delight\Auth\Auth::createUuid();

Reading and writing session data

For detailed information on how to read and write session data conveniently, please refer to the documentation of the session library, which is included by default.

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 (beyond expiration of browser session) 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 hijacking via cross-site scripting (XSS)
  - do not permit script-based access to cookies
  - restrict cookies to HTTPS to prevent session hijacking via non-secure HTTP
- protection against session fixation attacks
- protection against cross-site request forgery (CSRF)
  - works automatically (i.e. no need for CSRF tokens everywhere)
  - do not use HTTP GET requests for "dangerous" operations
throttling
- per IP address
- per account
enhanced HTTP security
- prevents clickjacking
- prevent content sniffing (MIME sniffing)
- disables caching of potentially sensitive data
miscellaneous
- ready for both IPv4 and IPv6
- works behind proxy servers as well
- privacy-friendly (e.g. does not save readable IP addresses)

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

Serve all pages over HTTPS only, i.e. using SSL/TLS for every single request.
You should enforce a minimum length for passwords, e.g. 10 characters, but never any maximum length, at least not anywhere below 100 characters. Moreover, you should not restrict the set of allowed characters.
Whenever a user was remembered through the "remember me" feature enabled or disabled during sign in, which means that they did not log in by typing 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, 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 verify their login credentials 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

This project is licensed under the terms of the MIT License.

README.md

Auth

Why do I need this?

Requirements

Installation

Usage

Creating a new instance

Registration (sign up)

Login (sign in)

Email verification

Keeping the user logged in

Password reset ("forgot password")

Changing the current user's password

Logout

Accessing user information

Login state

User ID

Email address

Display name

Checking whether the user was "remembered"

IP address

Additional user information

Administration (managing users)

Creating new users

Utilities

Creating a random string

Creating a UUID v4 as per RFC 4122

Reading and writing session data

Features

Exceptions

General advice

Contributing

License