Design And Implementation Of Bluetooth Secure Link Manager

With the widely application of bluetooth technology, researchers pay more and moreattention to the problem of its security. Analyzing and summing up the security threatens anddeficiencies, the security of bluetooth is improved with hardware and firmware in this paper, thelayered hierarchy of security service and the overall structure of bluetooth link manager aredesigned, which specify the security mechanisms need to add or improve, and the functionassignment and implementation form of functional module offering security service. Then,combining with bluetooth specification and characteristic of link layer, self-governing linkmanager and security enhanced scheme are designed. Finally, the prototype system of bluetoothsecure link manager is implemented.Aiming at the security deficiencies of bluetooth simple pairing protocol, a public keyexchange phase based on LUC key agreement protocol is designed, and combining with thebluetooth address and clock of the master, the security of authentication stage1is enhanced. Asecurity improved simple pairing protocol is got sequentially, which can not only resistimpersonation, replay attack and man in the middle attack, but also need little cost andconvenient for user.In order to resolve the security vulnerabilities of the bluetooth unit key, a security enhancedscheme is designed according to requirement. In the scheme, the bluetooth unit key is changedalong with the communication of the master according to a designed updating algorithm.Analysis results demonstrate that the scheme can protect the unit key against attack and do notincrease the memory cost, computing complexity and updating time.Aiming at the bluetooth DOS attack, channel quality scheme based on bit error and notavailable rate is designed to detect the DOS attack out the piconet, device characteristics schemebased on state transition is designed to detect the DOS attack in the piconet, and the defensemechanism to the attack is firmware realized using the self-defining LMP protocol data unit. Andthe system efficiency is increased effectively.According to the work above, prototype system of bluetooth secure link manager isimplemented based on baseband controller,, and the function of link and security managementare tested. The test results demonstrate that the system can establish connection and transmit datanormally, and realize the secure pairing, management of unit key and defense against DOS attack,which achieve the desired goals. The researches of the paper are beneficial to independence andcontrollability of bluetooth secure application, and offer a new means to widen the applied rangeof bluetooth technology.