Apparatus and method for managing security keys in wireless communication system

A method performed by a user equipment (UE) in a wireless communication system, wherein the wireless communication system is configured to operate in dual connectivity (DC) mode and further comprises a master cell group (MCG) controlled by a master node (MN) and a secondary cell group (SCG) controlled by a secondary node (SN), the method comprising:

• receiving, from the SN, a first message informing that a security key refresh is to be performed;
• and
• transmitting, to the SN, a second message indicating that a security key has been refreshed,
• wherein the security key for the SN is generated based on a counter value of the SN and a security key for the MN,
• wherein, at initialization, the MN provides an initial security key, and
• wherein the refreshed security key is generated by deriving the refreshed security key from a current security key.

A secondary node (SN) controlling a secondary cell group (SCG) in a wireless communication system, wherein the wireless communication system is configured to operate in dual connectivity (DC) mode and further comprises a master cell group (MCG) controlled by a master node (MN), the secondary node comprising:

• a transceiver;
• and
• at least one processor operably coupled to the transceiver,
• wherein the at least one processor is configured to:
• transmit, to a user equipment (UE), a first message informing that a security key refresh is to be performed, and
• receive, from the UE, a second message indicating that a security key has been refreshed, and
• wherein the security key for the SN is generated based on a counter value of the SN and a security key for the MN,
• wherein, at initialization, the MN provides an initial security key, and
• wherein the refreshed security key is generated by deriving the refreshed security key from a current security key.