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Okta PHP Quickstart

Now that your users can sign in, let's add authentication to your server.

Redirecting to Authorization Endpoint

First you need to generate a URL to the authorization endpoint for the Authorization Server and redirect the user.

Note: https://{yourOktaDomain} is different from your admin URL. Don’t include -admin in the value.
When copying your Okta domain from the developer console, you can find the correct value in upper right corner of the dashboard.

<?php

$query = http_build_query([
    'client_id' => '{{CLIENT_ID}}',
    'response_type' => 'code',
    'response_mode' => 'query',
    'scope' => 'openid profile',
    'redirect_uri' => 'http://localhost/login_callback.php',
    'state' => $state,
    'nonce' => $nonce
]);

header('Location: ' . 'https://{yourOktaDomain}/oauth2/default/v1/authorize?'.$query);

The nonce should be a generated string such as UUID, and the state can be any string representing state of the application.

Exchange Auth Code

After a successful login from the redirect, a code will be present in the request object.

This code should be placed in the file specified for your redirect_uri from the previous step.

<?php

if(array_key_exists('state', $_REQUEST) && $_REQUEST['state'] !== $state) {
    throw new \Exception('State does not match.');
}

if(array_key_exists('code', $_REQUEST)) {
    $exchange = exchangeCode($_REQUEST['code']);
}

function exchangeCode($code) {
    $authHeaderSecret = base64_encode( '{CLIENT_ID}:{CLIENT_SECRET}' );
    $query = http_build_query([
        'grant_type' => 'authorization_code',
        'code' => $code,
        'redirect_uri' => 'http://localhost/login_callback.php'
    ]);
    $headers = [
        'Authorization: Basic ' . $authHeaderSecret,
        'Accept: application/json',
        'Content-Type: application/x-www-form-urlencoded',
        'Connection: close',
        'Content-Length: 0'
    ];
    $url = 'https://{yourOktaDomain}/oauth2/default/v1/token?' . $query;
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
    curl_setopt($ch, CURLOPT_POST, 1);
    $output = curl_exec($ch);
    $httpcode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    if(curl_error($ch)) {
        $httpcode = 500;
    }
    curl_close($ch);
    return json_decode($output);
}

The result of this will provide you with an access token for that user.

$jwt = $exchange->access_token;

This access token is a JWT and should be verified according to the process described in Validate access tokens. This verification can be done easily with the Okta JWT Verifier for PHP.

Handling Errors

If an error is present in the login, an error query parameter will be present.

if(array_key_exists('error', $_REQUEST)) {
    throw new \Exception($_REQUEST['error']);
}