Abstract: Authentication in an ad-hoc network is established between a first device (for example a service-requesting device) and a second device (for example a service-providing device) using a third device (a peer device). An authentication request is transmitted from the first device to the second device. The second device transmits a query message to at least one third device (i.e. peer device). If the peer device has previously been authenticated with the first device, the peer device sends an authentication credential, for example an authentication key, to the first and second devices. Upon receiving the authentication credential, the first device sends the authentication credential to the second device. The second device then compares the authentication credential received from the first device with the authentication credential received from the third device, and authenticates the first device with the second device if the authentication credentials match.