Security establishment method, terminal device, and network device

A terminal device in which a subscriber identity module used to recognize a subscriber can be mounted, the terminal device comprising:

• a first key generating unit that generates a first temporary key by using a pair of keys consisting of an encryption key and an integrity key generated based on secret information stored in the subscriber identity module;
• a second key generating unit that generates, by using the first temporary key, a second temporary key mapped with a security anchor function of a roaming destination network of the terminal device;
• and
• a third key generating unit that:
• inputs, into a Key Derivation Function (KDF), the second temporary key and a subscription permanent identifier (SUPI) used to recognize the subscriber in the serving network;
• and
• generates a third temporary key mapped with access and mobility administration function of the roaming destination network, by using at least:
• the second temporary key;
• the SUPI;
• and
• information of capabilities or a feature set of the security anchor function of the roaming destination.

A network device capable of performing communication with a terminal device in which a subscriber identity module used to recognize a subscriber can be mounted, the network device comprising:

• a first key generating unit that generates a first temporary key by using a pair of keys consisting of an encryption key and an integrity key generated based on secret information stored in the subscriber identity module;
• a second key generating unit that generates, by using the first temporary key, a second temporary key mapped with a security anchor function of a roaming destination network of the terminal device;
• and
• a third key generating unit that:
• inputs, into a Key Derivation Function (KDF), the second temporary key and a subscription permanent identifier (SUPI) used to recognize the subscriber in the serving network;
• and
• generates a third temporary key mapped with access and mobility administration function of the roaming destination network, by using at least:
• the second temporary key;
• the SUPI;
• and
• information of capabilities or a feature set of the security anchor function of the roaming destination.