Analyzing the Secure Simple Pairing in Bluetooth v4.0

This paper analyzes the security of Bluetooth v4.0’s Secure Simple Pairing (SSP) protocol, for both the Bluetooth Basic Rate/Enhanced Data Rate (BR/EDR) and Bluetooth Low Energy (LE) operational modes. Bluetooth v4.0 is the latest version of a wireless communication standard for low-speed and low-range data transfer among devices in a human’s PAN. It allows increased network mobility among devices such as headsets, PDAs, wireless keyboards and mice. A pairing process is initiated when two devices desire to communicate, and this pairing needs to correctly authenticate devices so that a secret link key is established for secure communication. What is interesting is that device authentication relies on humans to communicate verification information between devices via a human-aided out-of-band channel. Bluetooth v4.0’s SSP protocol is designed to offer security against passive eavesdropping and man-in-the-middle (MitM) attacks. We conduct the first known detailed analysis of SSP for all its MitM-secure models. We highlight some issues related to exchange of public keys and use of the passkey in its models and discuss how to treat them properly.