Methods for authenticating peer mobile network nodes for establishing a secure peer-to-peer communications context in an ad-hoc network are presented. The methods include accessing wireless infrastructure network entities at low bandwidth and for a short time duration to obtain cryptographic information regarding a peer mobile network node for the purpose of establishing secure peer-to-peer communications therewith ad-hoc network. Having received cryptographic information regarding a peer mobile network node, the method further includes challenging the peer network node with a challenge phrase derived from the cryptographic information received, receiving a response, and establishing a secure communications context to the peer mobile network node based on the validity of the received response. Advantages are derived from addressing security threats encountered in provisioning ad-hoc networking, by leveraging wireless infrastructure network security architecture, exemplary deployed in UMTS/GSM infrastructure networks, enabling seamless mobile network node authentication through the existing UMTS and/or GSM authentication infrastructure, while pervasively communicating with peer mobile network nodes in an ad-hoc network.