Bluetooth, a proprietary open wireless technology, is a universal radio interface in the 2.45 Ghz frequency band that facilitates data connection and communication over short distances between portable electronic devices.  Invented by Ericsson Mobile Communication in 1994, Bluetooth technology can simultaneously communicate with up to seven other units per piconet, and each unit can be linked to several piconets (two or more Bluetooth units that have a common channel are referred to as a piconet). 
Bluetooth can operate over a short distance, is low power, and supports peer-to-peer communication, including both data and voice services, across different types of handheld and mobile devices.  Such wireless technology that can replace cables is suitable for a variety of mobile device connection applications, including connecting a mobile cellular phone to the Public Switched Telephone Network (PSTN), or connecting a mobile cellular phone to a notebook PC or a headset. 
To carry data communication necessary for audio, there are two different types of links used between two or more communicating devices: the Synchronous Connection Oriented (SCO) links used for voice communication, and the Asynchronous Connectionless (ACL) links used for data communication. ACL data packets consist of a 72-bit access code, a 54-bit packet header, and a 16-bit CRC code. A DH5 packet carries the largest data payload, which is up to 339 bytes, or 2,712 bits of data. 
The Bluetooth security layer consists of the following four key elements: a Bluetooth device address, an authentication key type, an encryption key type, and a random number.  The security layer of Bluetooth, which includes user and device authentication, data encryption, and key management and generation mechanisms, is one of the baseband layers, such that the upper layers have control over. 
Articles have pointed out potential vulnerabilities in the Bluetooth standard. Jakobsson and Wetzel have identified vulnerabilities such that an adversary can determine exchanges between two devices, allowing for eavesdropping.  In addition to eavesdropping and impersonation vulnerabilities, susceptibility to revealing graphical location of victim devices and issues with the cipher can also arise. 
Nonetheless, Bluetooth wireless technology has numerous advantages that has led to its widespread adoption, including an open publicly-available specification that is also royalty-free, its wireless capability that allows devices to communicate over a single air-interface cable-free, its ability to support both voice and data, and its ability to use an unregulated frequency band that is available anywhere in the world. 
© Danielle Rasooly. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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