SWRU271I October 2010 – January 2020 CC2540 , CC2540T , CC2541 , CC2541-Q1 , CC2640R2F
This section describes Bluetooth Low Energy security methods. For more information, see Device Information Service (Bluetooth Specification), Version 1.0 (24-May-2011).
When connected, the devices can go through a process called pairing. When paired, keys are established that encrypt and can authenticate the link. Either device may require a passkey to complete the pairing process. This process is called man in the middle (MITM) protection. You could create this passcode with a value such as 000000. Alternatively, the passcode can be a predetermined randomly-generated value displayed on the device. After the correct passkey is displayed and entered, the devices exchange security keys to encrypt and authenticate the link. The input and output capabilities of the devices in the pairing request must match to make authentication is possible.
In many cases, the same central and peripheral devices often connect and disconnect from each other. Bluetooth Low Energy has a security feature that lets the devices exchange a long-term set of security keys when pairing. With this long-term set of security keys, re-pairing is unnecessary when reconnecting in the future. This feature is called bonding and it lets the devices store the security keys and quickly reestablish encryption and authentication after reconnecting without going through the pairing process.