Method and apparatus for performing integrity verification in wireless communication system

A user equipment (UE) configured to operate in a wireless communication system, the UE comprising:

• a transceiver;
• at least one processor;
• and
• at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising:
• receiving, through the transceiver, a data unit from a network;
• performing integrity verification using the data unit;
• and
• when the integrity verification fails, reporting information about an integrity verification failure to the network through the transceiver,
• wherein the information about the integrity verification failure comprises (i) a radio bearer identity associated with the integrity verification failure, and (ii) at least one Packet Data Convergence Protocol (PDCP) COUNT value associated with the radio bearer identity.