Cognitive Radio Networks (CRNs) have come out as an encouraging next-generation network technology that addresses the issues related to dynamic Spectrum Access and enhanced utilization of spectrum in a significant manner. Specifically Trust, Reputation Management models and Cross layer defense mechanism are more and more regarded for CRNs to secure them against the attacks posed by the secondary users. In this Work, a method called, Mean Bid Trust & Multiple Nash Reputation (MBT-MNR) and Optimized Levensthein Cross layer Defense framework methods are proposed to secure the CRN by detecting...