6G security 6G wireless communications AVISPA BAN logic CNN DV-Hop Internet of Things LPWAN MDA Rice channels RoR model WirelessHART aggregator-based grouping amplify-and-forward relay authentication biometric bitslice cipher blockchain chi-square code abiding communication system security convolutional neural network counterfeit detection covert channel cube attack cybersecurity device fingerprinting digital twin dilated CNN distance vector hop