A network includes a server and a number of clients, which will in operation of the network require authentication by the server. The server distributes authentication information to other clients when a session is initialized. When the server needs to authenticate a client, it hands out a server request to the client which asks client for authentication information which it must obtain from other clients. The client to be authenticated then sends these requests to the clients specified in the authentication request to obtain the authentication information from those clients. Once the client to be authenticated has received the relevant authentication information from the other clients it returns it to the server and is authenticated or not accordingly.