Embodiments of the present disclosure relate to methods and devices for an authentication of an identity of a user. In example embodiments, the client device reads a digital tag associated with a service to be accessed, the digital tag being encoded with an identifier associated with a service provider that provides the service. The client device then decodes the digital tag to obtain the identifier. Further, the client device determines an authentication proxy associated with the service provider, and sends, to the associated authentication proxy, the identifier and a first request for an authentication of an identity of a user associated with the client device. In this way, the security of the authentication of the identity of the user may be significantly improved.