An apparatus comprising: a requester configured to request a certificate comprising at least one identifier associated with the apparatus from at least one network node; a first receiver configured to receive the certificate from the at least one network node; and a forwarder configured to forward the certificate to at least one further apparatus; a second receiver configured to receive a further certificate from the further apparatus, the further certificate comprising at least one further identifier associated with the further apparatus; and an authenticated configured to authenticate the further apparatus based on the further certificate.