Authentication device, network device, communication system, authentication method, and non-transitory computer readable medium

A network device comprising:

• at least one memory storing instructions, and
• at least one processor configured to execute the instructions to:
• in registration processing of a UE, acquire authentication information generated based on a master key generated by use of a pseudo random function supported by a UE indicated in UE KDF capabilities included in a registration request message transmitted from the UE;
• store the authentication information;
• and
• in re-registration processing of the UE, send the stored authentication information in response to a message requesting authentication information.

An authentication method comprising:

• receiving a registration request message including user equipment (UE) key derivation function (KDF) capabilities indicating a pseudo random function supported by the UE transmitted from the UE;
• acquiring the UE KDF capabilities;
• selecting a pseudo random function used for generation of a master key related to the UE by use of the UE KDF capabilities;
• and
• generating a master key related to the UE by use of the selected pseudo random function.