Method, apparatus and system for authentication on peer-to-peer file sharing network

A method of authenticating a first peer-to-peer ("P2P") file sharing ("FS") application, and related apparatus, are disclosed. In at least some embodiments, the method includes (a) providing an identifier from a second P2P FS application to a second authenticated application associated therewith, and (b) transmitting the identifier from the second authenticated application for receipt by a first authenticated application and subsequently by the first P2P FS application with which the first authenticated application is associated. The method further includes (c) receiving the identifier at the second P2P FS application subsequent to the transmitting of the identifier in (b), and (d) authenticating the first P2P FS application if the identifier received in (c) corresponds to that provided in (a). The authenticated applications can be, in at least some embodiments, instant messaging applications. The method can be employed in conjunction with various computerized devices including, for example, cellular telephones and personal computers.