MTC key management for key derivation at both UE and network

A method of a User Equipment (UE) in a mobile communication system including a Mobility Management Entity (MME), a network server, a network node that differs from the MME, and a Home Subscriber Server (HSS), the method comprising:

• performing first communication with the network node by receiving a first message including first security information from the network node, when the network node receives a second message from the network server and derives a first key, a second key, and a third key based on second security information received from the HSS;
• deriving a fourth key same as the first key, a fifth key same as the second key, and a sixth key same as the third key with the network node based on the first security information;
• protecting the first communication using first confidential protection based on the fifth key and first integrity protection based on the sixth key;
• performing second communication with the network server using the first communication;
• and
• protecting the second communication using second confidential protection and second integrity protection.

A network node in a mobile communication system including a User Equipment (UE), a Mobility Management Entity (MME) that differs from the network node, a network server, and a Home Subscriber Server (HSS), the network node comprising:

• at least one processor;
• and
• at least one memory coupled to the at least one processor, the at least one memory storing instructions that when executed by the at least one processor cause the at least one processor to:
• receive a second message from the network server,
• receive second security information from the HSS,
• derive a first key, a second key and a third key based on the second security information,
• perform first communication with the UE by sending a first message including first security information to the UE, the UE deriving a fourth key same as the first key, a fifth key same as the second key, and a sixth key same as the third key with the network node based on the first security information, and
• protect the first communication using first confidential protection based on the fifth key and first integrity protection based on the sixth key,
• wherein the UE performs second communication with the network server using the first communication and protects the second communication using second confidential protection and second integrity protection.

A method of a network node in a mobile communication system including a User Equipment (UE), a Mobility Management Entity (MME) that differs from the network node, a network server, and a Home Subscriber Server (HSS), the method comprising:

• receiving a second message from the network server;
• receiving second security information from the HSS;
• deriving a first key, a second key and a third key based on the second security information;
• performing first communication with the UE by sending a first message including first security information to the UE, the UE deriving a fourth key same as the first key, a fifth key same as the second key, and a sixth key same as the third key with the network node based on the first security information;
• and
• protecting the first communication using first confidential protection based on the fifth key and first integrity protection based on the sixth key,
• wherein the UE performs second communication with the network server using the first communication and protects the second communication using second confidential protection and second integrity protection.