Method for ue-to-ue relay reselection security and privacy

A relay wireless transmit receive unit (WTRU) comprising:

• processor circuitry;
• and
• a transceiver operatively coupled to the processor circuitry and configured to:
• establish a unicast connection between a first WTRU and a second WTRU;
• send, to the second WTRU, a link modification request (LMR) message received from the first WTRU, the LMR message including a request for a coordinated release of the unicast connection between the first WTRU and the second WTRU;
• send, to the first WTRU, a link modification accept (LMA) message received from the second WTRU, the LMA message including an acceptance of the coordinated release of the unicast connection between the first WTRU and the second WTRU;
• send, to the second WTRU, a link release request message received from the first WTRU, the link release request message including one or more new most significant bytes (MSBs) of a new Key NR ProSe identifier (KNRP ID);
• and
• send, to the first WTRU, a link release response message received from the second WTRU, the link release response message including one or more new least significant bytes (LSBs) of the new KNRP ID, wherein the new KNRP ID is formed by combining the one or more new MSBs and the one or more new LSBs.