A method for exchanging messages containing reliable information between nodes in an ad hoc network, such as a vehicle ad hoc network. The method includes the steps of providing a public key for a PKI encrypted certificate authority signature to all nodes known to transmit reliable information. Each node transmits a signal containing node identification information and the PKI encrypted certificate authority signature associated with that node. Each node also receives like signals from other nodes and then decrypts the certificate authority signatures from the received signals by using the certificate authority public key to ascertain the authenticity of the received certificate authority signatures and the reliability of the received message. Thereafter, the nodes receive and accept messages with a TESLA encrypted signature only with nodes identified to have authentic certificate authority signatures until the occurrence of a subsequent predefined event, such as a new node in the network or the elapse of a predetermined time period.