MTC key management for sending key from network to UE

A method of a User Equipment (UE), in a mobile communication system including a first network node, a second network node, and a third network node, the first network node communicatively coupled between the UE and the second network node, the method comprising:

• sending, to the first network node, a first message including capability information;
• receiving a second message, from the first network node, wherein the first network node receives, from the third network node, a third message including key information related to derivation of a first key, derives the first key based on the key information, and sends a fourth message including the first key to the second network node that derives a confidentiality key and an integrity key from the first key;
• deriving the confidentiality key and the integrity key from the first key based on the receipt of the second message;
• and
• encrypting and decrypting messages between the UE and the second network node using the confidentiality key.

A first network node in a mobile communication system including a User Equipment (UE), a second network node, and a third network node, the first network node communicatively coupled between the UE and the second network node, the first 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, from the UE, a first message including capability information,
• send a second message to the UE,
• receive, from the third network node, a third message including key information related to derivation of a first key,
• derive the first key based on the key information, and
• send a fourth message including the first key to the second network node, wherein the second network node derives a confidentiality key and an integrity key from the first key and performs secure communication with the UE using the confidentiality key and the integrity key.

A method of a first network node in a mobile communication system including a User Equipment (UE), a second network node, and a third network node, the first network node communicatively coupled between the UE and the second network node, the method comprising:

• receiving, from the UE, a first message including capability information;
• sending a second message to the UE;
• receiving, from the third network node, a third message including key information related to derivation of a first key;
• deriving the first key based on the key information;
• and
• sending a fourth message including the first key to the second network node, wherein the second network node derives a confidentiality key and an integrity key from the first key and performs secure communication with the UE using the confidentiality key and the integrity key.