CPC H04L 9/0861 (2013.01) [H04L 9/0833 (2013.01); H04L 63/205 (2013.01); H04W 12/02 (2013.01); H04W 12/033 (2021.01); H04L 63/162 (2013.01); H04L 69/22 (2013.01); H04L 2209/80 (2013.01); H04W 12/04 (2013.01)] | 17 Claims |
1. A method of transmitting data in a device to device communication system, the method comprising:
determining whether a security feature is applied to a packet data convergence protocol (PDCP) service data unit (SDU);
configuring a PDCP protocol data unit (PDU) based on the determination; and
transmitting the PDCP PDU to a receiving user equipment (UE),
wherein a PDCP header of the PDCP PDU includes an SDU type, a PDCP sequence number (SN), and a first key identification (ID),
wherein, in case that the security feature is applied to the PDCP SDU, the first key ID is set to a value for identifying a first key, the first key being used to generate an encryption key for securing the PDCP SDU and being generated based on a second key identified by a second key ID, and
wherein, in case that the security feature is not applied to the PDCP SDU, the first key ID is set to a zero value.
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