The Relying Party

The Relying Party (or rp) corresponds to the application that will ask for the user to interact with the authenticator.

The library provides a simple class to handle the rp information: Webauthn\PublicKeyCredentialRpEntity.

<?php

use Webauthn\PublicKeyCredentialRpEntity;

$rpEntity = new PublicKeyCredentialRpEntity(
    'ACME Webauthn Server', // The application name
    'acme.com'              // The application ID = the domain
);

This $rpEntity object will be useful for the next steps.

The ID can be null, the domain or sub-domain of your application.

Even if it is optional, we highly recommend to set the application ID. If absent, the current domain will be used

The scheme, userinfo, port, path, user… are not allowed.

Example: www.sub.domain.com, sub.domain.com, domain.com but not com, www.sub.domain.com:1337, https://domain.com:443, sub.domain.com/index, https://user:[e-mail].

Your application may also have a logo. You can indicate this logo as third argument. Please note that for safety reason this icon is a priori authenticated URL i.e. an image that uses the data scheme.

<?php

use Webauthn\PublicKeyCredentialRpEntity;

$rpEntity = new PublicKeyCredentialRpEntity(
    'ACME Webauthn Server',
    'acme.com',
    'data:image/png;base64,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'
);

The Webauthn specification does not set any limit for the length of the third argument.

The icon may be ignored by browsers, especially if its length is greater than 128 bytes.