chillerlan/php-authenticator

A generator for counter based (RFC 4226) and time based (RFC 6238) authentication codes. (a.k.a. Yet Another Google Authenticator Implementation!), _(*1)

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Documentation

Requirements

PHP 7.2+
- 64bit

Installation

requires composer, _(*3)

composer.json (note: replace dev-master with a version boundary), _(*4)

{
    "require": {
        "php": "^7.2",
        "chillerlan/php-authenticator": "dev-master"
    }
}

Manual installation

Download the desired version of the package from master or release and extract the contents to your project folder. After that: - run composer install to install the required dependencies and generate /vendor/autoload.php. - if you use a custom autoloader, point the namespace chillerlan\Authenticator to the folder src of the package, _(*5)

Profit!, _(*6)

Usage

Create a secret

The secret is usually being created once during the activation process in a user control panel. So all you need to do there is to display it to the user in a convenient way - as a text string and QR code for example - and save it somewhere with the user data., _(*7)

use chillerlan\Authenticator\{Authenticator, AuthenticatorOptions};

$options       = new AuthenticatorOptions;
$authenticator = new Authenticator($options);

// create a secret (stored somewhere in a *safe* place on the server. safe... hahaha)
$options->secret_length = 32;
$authenticator->setOptions($options);
$secret = $authenticator->createSecret();

// you can also specify the length of the secret key, which overrides the options setting
$secret = $authenticator->createSecret(20);

// set an existing secret
$authenticator->setSecret($secret);

// via the constructor:
$authenticator = new Authenticator($options, $secret);

A secret created with Authenticator::createSecret() will also be stored internally, so that you don't need to provide the one you just created on follow-up operations for the same secret., _(*8)

Verify a one time code

Now during the login process - after the user has successfully entered their credentials - you would ask them for a one time code to check it against the secret from your user database., _(*9)

// verify the code
if($authenticator->verify($code)){
    // that's it - 2FA has never been easier! :D
}

time based (TOTP)

Verify adjacent codes, _(*10)

// try the first adjacent
$authenticator->verify($code, time() - $options->period); // -> true

// try the second adjacent, default is 1
$authenticator->verify($code, time() + 2 * $options->period); // -> false

// allow 2 adjacent codes
$authenticator->verify($code, time() + 2 * $options->period, 2); // -> true

Create a code for a UNIX timestamp, _(*11)

// let's assume your server's timezone is an hour off and beyond your control
$timeslice = $authenticator->timeslice(time() - 3600);

// current code
$code = $authenticator->code($timeslice);

// adjacent codes
$prev = $authenticator->code($timeslice - 1);
$next = $authenticator->code($timeslice + 1);

counter based (HOTP)

// switch mode to HOTP
$options->mode = 'hotp';
$authenticator->setOptions($options);

// user sends code #42, equivalent to
$code = $authenticator->code(42); // -> 123456

// verify [123456, 42]
$authenticator->verify($code, $counterValueFromUserDatabase) // -> true

URI creation

In order to display a QR code for a mobile authenticator you'll need an otpauth:// URI, which can be created using the following method. - $label should be something that identifies the account to which the secret belongs - $issuer is the name of your website or company for example, so that the user is able to identify multiple accounts., _(*12)

$uri = $authenticator->getUri($label, $issuer);

// -> otpauth://totp/my%20label?secret=NKSOQG7UKKID4IXW&issuer=chillerlan.net&digits=6&algorithm=SHA1&period=30

API

`Authenticator`

method	return	description
`__construct(SettingsContainerInterface $options = null, string $secret = null)`	-
`setOptions(SettingsContainerInterface $options)`	`Authenticator`	called internally by `__construct()`
`setSecret(string $secret)`	`Authenticator`	called internally by `__construct()`
`getSecret()`	string
`createSecret(int $length = null)`	string	`$length` overrides `AuthenticatorOptions` setting
`timeslice(int $timestamp = null)`	int
`code(int $data = null)`	string	`$data` may be a UNIX timestamp (TOTP) or a counter value (HOTP)
`verify(string $code, int $data = null)`	bool	see `Authenticator::code()`, `$data` will override the current counter value in HOTP mode
`getUri(string $label, string $issuer, int $hotpCounter = null)`	string

`AuthenticatorOptions` properties

property	type	default	allowed	description
`$digits`	int	6	6 or 8	auth code length
`$period`	int	30	15 - 60	validation period (seconds)
`$secret_length`	int	20	>= 16	length of the secret phrase (bytes, unencoded binary)
`$algorithm`	string	`SHA1`	`SHA1`, `SHA256` or `SHA512`	HMAC hash algorithm
`$mode`	string	`totp`	`totp` or `hotp`	Authenticator mode: time- or counter based, respectively
`$adjacent`	int	1	>= 0	number of allowed adjacent codes