To make our online offering even easier to use, we deploy a ‘single sign-on procedure’. This enables users to log on to our online offering with log-in details from a single sign-on provider, meaning that they do not need to have any additional log-in details as a result. The use of a single sign-on procedure requires users to already have an existing user account with a provider of the procedure in question, such as a social network. To log on with the single sign-on procedure, the user must provide their log-in details for the single sign-on procedure in the log-in window of our online offering, or if the user is already logged in on the provider's website, confirm registration via single sign-on by clicking the appropriate button.  We use ‘user handles’ to carry out authentication. Inter alia, this includes a user ID plus information that the user has used the ID to log on with the procedure provider in question. We only receive this ID for the purposes of authentication, i.e. we are not permitted to process it for any purposes beyond authentication. Whether data beyond this is transferred to us, and if yes, what data, depends on the provider of the procedure in question, the user’s account settings with this provider and any data approvals selected within the framework of authentication. The data we receive from the provider of the procedure in question can vary. However, it usually encompasses an email address and a username. We cannot see the password entered, nor can we store it.  To change or delete connections between user accounts and the single sign-on procedure, the appropriate settings must be changed within the user account with the provider of the procedure in question.  Categories of data subjects: Users of the function in question Data categories: User handles (e.g. username, authentication confirmation) Purposes of processing: Authentication of users Legal bases: Consent (article 6 (1) (a) GDPR)