Method, apparatus, and computer program for setting encryption key in wireless communication system, and recording medium for same

A first device in a wireless communication system, the first device comprising:

• a transceiver for performing signal transmission and reception with second device;
• and
• a processor for controlling the transceiver and the first device;
• wherein the processor is configured to:
• send, by a first host to a first controller via a first host controller interface (HCI), an HCI set minimum encryption key size command including a parameter specifying a minimum encryption key size;
• and
• receive, by the first host from the first controller via the first HCI, an HCI encryption change event including a first parameter indicating that an encryption change has occurred,
• wherein the HCI encryption change event includes a second parameter specifying a size of a key used for an encryption, and the first controller does not negotiate a key size smaller than the minimum encryption key size,
• wherein the HCI encryption change event further includes a third parameter of an identifier for a connection between a first device and a second device,
• wherein the HCI encryption change event occurs on the first device to notify the first host when encryption has changed for the connection existing between the first device and the second device, and
• wherein, based on the first host specifying the minimum encryption key size that the first controller does not support, the first controller returns error information to the first host;
• wherein the HCl encryption change event further includes a fourth parameter on whether link level encryption is enabled or disabled;
• wherein the link level encryption is enabled, with either E0 (Encryption 0) or AES-CCM (Advanced Encryption Standard-Cipher block Chaining-Message authentication code).