README

PHP implementation of OpenID Connect using symfony/contracts

Install

Via Composer

$ composer require digitalcz/openid-connect

Usage

Initialization

Using the OIDC discovery endpoint

use DigitalCz\OpenIDConnect\OidcFactory;
use Symfony\Component\HttpClient\HttpClient;

$httpClient = HttpClient::create();

$oidc = OidcFactory::create(
    httpClient: $httpClient,
    issuer: 'https://auth.example.com',
    clientId: 'my-client-id',
    clientSecret: 'my-client-secret',
    redirectUri: 'https://myapp.example.com/callback',
);

use DigitalCz\OpenIDConnect\OidcFactory;
use DigitalCz\OpenIDConnect\Config\IssuerMetadata;
use Symfony\Component\HttpClient\HttpClient;

$httpClient = HttpClient::create();

$issuerMetadata = new IssuerMetadata([
    'authorization_endpoint' => 'https://auth.example.com/authorize',
    'token_endpoint' => 'https://auth.example.com/token',
    'jwks_uri' => 'https://auth.example.com/.well-known/jwks.json',
    'issuer' => 'https://auth.example.com',
]);

$oidc = OidcFactory::create(
    httpClient: $httpClient,
    issuer: $issuerMetadata,
    clientId: 'my-client-id',
    clientSecret: 'my-client-secret',
    redirectUri: 'https://myapp.example.com/callback',
);

Configuration Options

The OidcFactory::create() method accepts the following configuration options:

Authentication Methods

• client_secret_post - Send client credentials in POST body
• client_secret_basic - Send client credentials in Authorization header
• client_secret_jwt - Use JWT signed with client secret
• private_key_jwt - Use JWT signed with private key
• none - No client authentication (public clients)

Authorization Code flow

Step 1 - Redirect the user to authorization endpoint

$authorizationCode = $oidc->authorizationCode();

// createAuthorizationUrl() auto-generates cryptographically random state, nonce, and PKCE
// code_verifier. Retrieve them from the result and persist in session before redirecting.
$result = $authorizationCode->createAuthorizationUrl();

// IMPORTANT: Store security parameters in session before redirecting.
// - state: must be verified on callback to prevent CSRF attacks
// - nonce: must be passed to fetchTokens() to validate the ID token
// - codeVerifier: must be passed to fetchTokens() when PKCE is enabled (default)
session_start();
$_SESSION['oauth_state'] = $result->state();
$_SESSION['oauth_nonce'] = $result->nonce();
$_SESSION['oauth_code_verifier'] = $result->codeVerifier();

// Redirect user to $result->url()

Step 2 - Handle the callback and exchange code for tokens

session_start();

// IMPORTANT: Always validate the state parameter before proceeding.
// A missing or mismatched state indicates a potential CSRF attack.
if (
    empty($_GET['state'])
    || !isset($_SESSION['oauth_state'])
    || !hash_equals($_SESSION['oauth_state'], $_GET['state'])
) {
    throw new RuntimeException('Invalid state parameter - possible CSRF attack.');
}

$code = $_GET['code'];

$tokens = $authorizationCode->fetchTokens(
    code: $code,
    nonce: $_SESSION['oauth_nonce'],
    codeVerifier: $_SESSION['oauth_code_verifier'],
);

// Clear one-time security parameters from session
unset($_SESSION['oauth_state'], $_SESSION['oauth_nonce'], $_SESSION['oauth_code_verifier']);

echo "Access Token: " . $tokens->accessToken() . PHP_EOL;
echo "ID Token: " . $tokens->idToken() . PHP_EOL;
echo "Refresh Token: " . $tokens->refreshToken() . PHP_EOL;

Client Credentials flow

$clientCredentials = $oidc->clientCredentials();
$tokens = $clientCredentials->fetchTokens();

echo "Access Token: " . $tokens->accessToken() . PHP_EOL;

Device Authorization flow

Implements the OAuth 2.0 Device Authorization Grant (RFC 8628) for browserless and input-constrained devices. Requires the provider to expose a device_authorization_endpoint.

Step 1 - Request a device and user code

$device = $oidc->deviceAuthorization();

$response = $device->requestDeviceAuthorization();

// Show these to the user, who completes authorization on another device.
echo "Go to: " . $response->verificationUri() . PHP_EOL;
echo "Enter code: " . $response->userCode() . PHP_EOL;

// verificationUriComplete() embeds the code so the user can skip typing it (e.g. as a QR code).
if ($response->verificationUriComplete() !== null) {
    echo "Or open: " . $response->verificationUriComplete() . PHP_EOL;
}

Step 2 - Poll for tokens

pollForTokens() blocks until the user completes (or denies) authorization, honoring the server's polling interval and backing off automatically on slow_down:

use DigitalCz\OpenIDConnect\Exception\DeviceAuthorizationDeniedException;
use DigitalCz\OpenIDConnect\Exception\DeviceAuthorizationExpiredException;

try {
    $tokens = $device->pollForTokens($response);
    echo "Access Token: " . $tokens->accessToken() . PHP_EOL;
} catch (DeviceAuthorizationDeniedException $e) {
    echo "User denied the request." . PHP_EOL;
} catch (DeviceAuthorizationExpiredException $e) {
    echo "Device code expired - restart the flow." . PHP_EOL;
}

If you need to drive the polling loop yourself, call fetchTokens() for a single attempt. It throws a typed exception per RFC 8628 error code: DeviceAuthorizationPendingException, SlowDownException, DeviceAuthorizationExpiredException, DeviceAuthorizationDeniedException, or the base DeviceAuthorizationException for any other error.

Resource Server (Token Validation)

use DigitalCz\OpenIDConnect\ResourceServer\JwtAccessToken;
use DigitalCz\OpenIDConnect\ResourceServer\OpaqueAccessToken;
use DigitalCz\OpenIDConnect\Util\JWT;

$resourceServer = $oidc->resourceServer();

$accessToken = new JwtAccessToken($jwt);
$validatedToken = $resourceServer->introspect($accessToken);

echo "Token is valid for subject: " . $validatedToken->sub() . PHP_EOL;
echo "Token expires at: " . date('Y-m-d H:i:s', $validatedToken->exp()) . PHP_EOL;

To follow RFC 9068 and require JWT access tokens to be explicitly typed (rejecting, for example, an ID token presented as an access token), set accessTokenType:

$oidc = OidcFactory::create(
    httpClient: $httpClient,
    issuer: 'https://issuer.example.com',
    clientId: 'my-client',
    accessTokenType: 'at+jwt',
);

When set, the typ header must be present and equal to the expected value; both at+jwt and application/at+jwt are accepted. It is disabled by default because not all authorization servers emit the typ header.

Audience validation

By default the resource server's JWT access-token validator accepts only tokens whose aud claim matches the clientId (opaque tokens are unaffected — they're validated via introspection, which only checks active). Use resourceServerAudience to decouple the accepted audience from the client id — for example when the resource server has several identities of its own, or when it must accept tokens minted for other first-party services:

// Accept a token whose "aud" matches any of the listed audiences.
$oidc = OidcFactory::create(
    httpClient: $httpClient,
    issuer: 'https://issuer.example.com',
    clientId: 'my-client',
    resourceServerAudience: ['service-a', 'service-b'],
);

// Disable the audience check entirely (the "aud" value is no longer verified against anything;
// its presence is still required by the default mandatory-claims set).
$oidc = OidcFactory::create(
    httpClient: $httpClient,
    issuer: 'https://issuer.example.com',
    clientId: 'my-client',
    resourceServerAudience: null,
);

Passing a list verifies that the token's aud (a single value or an array) intersects the configured audiences — this is the standard model for a resource server with multiple identities (RFC 9068 §4).

Passing null turns the audience check off. This is a deliberate deviation from RFC 9068, which requires rejecting a token whose aud does not identify the resource server. It exists for closed first-party token propagation across services sharing one issuer; the standards-correct alternative is Token Exchange (RFC 8693). The presence of the aud claim itself is still governed by the validator's mandatory-claims set. Leaving resourceServerAudience unset keeps the default (aud must equal clientId).

When wiring JwtAccessTokenValidator manually, the same string|list<string>|null values apply to its $audience argument. For fully custom validation you can inject a replacement set of claim checkers via $claimCheckers, which then supersedes the default issuer/audience/expiry/issued-at/not-before checkers.

Back-Channel Logout

Implements OpenID Connect Back-Channel Logout 1.0. The OP sends a server-to-server POST with a logout_token to your registered back-channel logout endpoint. Pass that token to the handler — it verifies the signature against the issuer JWKS and validates the logout-token claims (iss, aud, iat, events, no nonce, and sub and/or sid).

use DigitalCz\OpenIDConnect\Exception\InvalidTokenException;

$handler = $oidc->backChannelLogout();

try {
    // $_POST['logout_token'] is the form-encoded parameter sent by the OP
    $logoutToken = $handler->handleLogoutRequest($_POST['logout_token']);
} catch (InvalidTokenException $e) {
    http_response_code(400);
    return;
}

// Terminate the matching session(s). Use sid (this session) and/or sub (all of the user's sessions).
$sid = $logoutToken->sid(); // ?string
$sub = $logoutToken->sub(); // ?string

http_response_code(200);

Two responsibilities the spec leaves to the application are intentionally left to you:

• Replay protection — verify the jti (exposed via $logoutToken->jti()) has not been seen recently before acting on the token.
• Session termination — map sid/sub to your session store and destroy the relevant session(s).

If the client is registered with backchannelLogoutSessionRequired: true, logout tokens without a sid claim are rejected.

See examples for more complete examples

Testing

$ composer csfix    # fix codestyle
$ composer checks   # run all checks 

# or separately
$ composer tests    # run phpunit
$ composer phpstan  # run phpstan
$ composer cs       # run codesniffer

Contributing

Please see CONTRIBUTING for details.

Security

If you discover any security related issues, please email devs@digital.cz instead of using the issue tracker.

Credits

• Digital Solutions s.r.o.
• All Contributors

License

The MIT License (MIT). Please see License File for more information.