1. A method for authenticating messages received at a receiver device, said method comprising: establishing a belief level for senders of messages that are received at the receiver device as to the messages validity; assigning the belief level to a scale where one end of the scale indicates a bona fide sender or message that will be accepted and the other end of the scale indicates a malicious sender or message that will be discarded; selecting an authentication mode based at least in part on the belief level, wherein one authentication mode includes a blind accept mode for a belief level at or around the bona fide end of the scale, a discard mode for a belief level at or around the malicious end of the scale and at least one mode therebetween; and performing an authentication process on the message depending on which mode is selected, wherein the at least one mode between the blind accept mode and the discard mode includes modes for validating a PKI signature, validating a lightweight signature and/or performing a consistency check based on local information, and wherein the PKI signature mode is selected if the belief level is near the malicious end of the scale and the lightweight signature mode is selected if the belief level is near the bona fide end of the scale.