AKMA Session Security for Fine-Grained AF Communication Protection

The patent segments the key negotiation process into two distinct phases: first negotiating a base key at AF identifier granularity, then negotiating service-specific keys at finer granularity for different service requirements. This segmentation allows the system to maintain the simplicity of coarse-grained key management while enabling fine-grained security protection when needed, resolving the contradiction between adaptability and complexity.

The patent introduces dynamic key negotiation capability that can adapt to different service requirements. The system dynamically selects whether to use the base key or negotiate additional service-specific keys based on the security requirements of each service, making the key management system flexible and adaptable without being overly complex for all scenarios.

The patent performs preliminary key negotiation at the AF identifier level before specific service communication occurs. This base key is established in advance and can be reused across multiple services, reducing the need for repeated key negotiations and minimizing the complexity increase while ensuring security protection is available when needed.

The patent implements partial key negotiation by only negotiating service-specific keys when actually needed for particular services, rather than pre-negotiating all possible service keys. This approach provides end-to-end security protection where required while avoiding the complexity of managing keys for all potential services, applying the principle of doing just enough rather than everything.