File: uploady/vendor/robthree/twofactorauth/docs/qr-codes.md

layout: post title: QR Codes

An alternative way of communicating the secret to the user is through the use of QR Codes which most if not all authenticator mobile apps can scan.

This can avoid accidental typing errors and also pre-set some text values within the users app.

You can display the QR Code as a base64 encoded image using the instance as follows, supplying the users name or other public identifier as the first argument

<p>Scan the following image with your app:</p>
<img src="<?php echo $tfa->getQRCodeImageAsDataUri('Bob Ross', $secret); ?>">

You can also specify a size as a third argument which is 200 by default.

Note: by default, the QR code returned by the instance is generated from a third party across the internet. If the third party is encountering problems or is not available from where you have hosted your code, your user will likely experience a delay in seeing the QR code, if it even loads at all. This can be overcome with offline providers configured when you create the instance.

Online Providers

QRServerProvider (default)

ImageChartsQRCodeProvider

QRicketProvider

Offline Providers

EndroidQrCodeProvider and EndroidQrCodeWithLogoProvider

BaconQRCodeProvider

Note: offline providers may have additional PHP requirements in order to function, you should study what is required before trying to make use of them.

Custom Provider

If you wish to make your own QR Code provider to reference another service or library, it must implement the IQRCodeProvider interface.

It is recommended to use similar constructor arguments as the included providers to avoid big shifts when trying different providers.

Using a specific provider

If you do not want to use the default QR code provider, you can specify the one you want to use when you create your instance.

use RobThree\Auth\TwoFactorAuth;

$qrCodeProvider = new YourChosenProvider();

$tfa = new TwoFactorAuth(
	null,
	6,
	30,
	'sha1',
	$qrCodeProvider
);

As you create a new instance of your provider, you can supply any extra configuration there.