The invention relates to a computer-implemented method for user authentication using a cryptographically secured register. An authentication request for authenticating the user is received. The user is authenticated using a root identity of the user. A successful authentication requires receiving a credential assigned to a root identifier of the root identity of the user. An authentication context of the requested authentication is identified. One of the one or more delegated identities assigned to the root identity of the user and assigned to the identified authentication context is identified. In response to a successful authentication of the user, an authentication token is issued confirming the successful user authentication and identifying the successfully authenticated user by the delegated identifier of the identified delegated identity.