Rf characteristic used to validate genuineness and counter a relay attack

A method of operating an authorization verifier device, the method comprising:

• receiving credential information included in a received RF signal;
• determining an RF fingerprint of the received RF signal, wherein the RF fingerprint includes one or more RF signal parameters determined for the received RF signal;
• authenticating the credential information and the RF fingerprint;
• and
• initiating access to a physical access portal in response to authentication of the credential information and the RF fingerprint.

A verifier device for an access control system, the device comprising:

• physical layer circuitry configured to transmit and receive radio frequency (RF) electrical signals;
• processing circuitry operatively coupled to the physical layer circuitry and including at least one hardware processor;
• and
• a memory storing instructions that cause the at least one hardware processor to perform operations including:
• receiving, by the verifier device, a message including credential information sent via a communication interface of a credential device;
• determining interface characterization data characterizing operation of the communication interface of the credential device, wherein the characterization data includes one or more communication parameters determined using the received message;
• authenticating the credential information and the interface characterization data;
• and
• initiating access to a physical access portal in response to authentication of the credential information and the interface characterization data.