PC5 Unicast RRC Signaling With Split Security Key Derivation

The security key derivation is segmented into two distinct processes: one for user plane (U-plane) communication and another for control plane (C-plane) communication. This segmentation allows each plane to have dedicated security keys derived from appropriate inputs, ensuring that security requirements specific to each communication type are met while enabling direct PC5 interface communication.

Security keys are derived and established before actual RRC signaling communication occurs over the PC5 interface. The WTRU derives security keys from security information exchanged during the connection setup phase, ensuring that integrity protection and encryption mechanisms are already in place before sensitive communication begins, thus preventing security vulnerabilities.

Different security key derivation methods are applied locally to different communication planes based on their specific security requirements. The user plane uses security keys derived from PC5 interface security information, while the control plane uses keys derived from RRC layer security information. This localized approach ensures each plane receives appropriate security protection without imposing unnecessary complexity on the other plane.

The security key derivation process changes parameters based on the communication plane type. For U-plane, keys are derived from PC5 security context including security capability information and nonces exchanged directly between WTRUs. For C-plane, keys are derived from RRC security context. This parameter adaptation allows comprehensive security coverage while managing complexity through context-aware key derivation.