Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances using UHF radio waves in the ISM bands, from 2.402 GHz to 2.48 GHz, and building personal area networks (PANs). In the most widely used mode, transmission power is limited to 2.5 milliwatts, giving it a very short range of up to 10 meters (30 feet).
The Bluetooth SIG oversees development of the specification, manages the qualification program, and protects the trademarks.
As of 2009 , Bluetooth integrated circuit chips ship approximately 920 million units annually. [6] By 2017, there were 3.6 billion Bluetooth devices shipping annually and the shipments were expected to continue increasing at about 12% a year. The name was inspired by a conversation with Sven Mattisson who related Scandinavian history through tales from Frans G. Bengtsson’s The Long Ships, a historical novel about Vikings and the 10th-century Danish king Harald Bluetooth.
Kardach was later quoted as saying, “King Harald Bluetooth…was famous for uniting Scandinavia just as we intended to unite the PC and cellular industries with a short-range wireless link.” Bluetooth was only intended as a placeholder until marketing could come up with something really cool. The development of the “short-link” radio technology, later named Bluetooth, was initiated in 1989 by Nils Rydbeck, CTO at Ericsson Mobile in Lund, Sweden.
Nils Rydbeck tasked Tord Wingren with specifying and Dutchman Jaap Haartsen and Sven Mattisson with developing. The conclusion was that power consumption on cellphone technology at that time was too high to allow viable integration into a notebook and still achieve adequate battery life.
It was a hands-free mobile headset that earned the “Best of show Technology Award” at COMDEX. The first Bluetooth mobile phone was the Ericsson T36 but it was the revised T39 model that actually made it to store shelves in 2001.
Bluetooth’s early incorporation into consumer electronics products continued at Vosi Technologies in Costa Mesa, California, USA, initially overseen by founding members Bejan Amini and Tom Davidson. Vosi Technologies had been created by real estate developer Ivano Stegmenga, with United States Patent 608507, for communication between a cellular phone and a vehicle’s audio system. Due to ongoing negotiations for an intended licensing agreement with Motorola beginning in the late 1990s, Vosi could not publicly disclose the intention, integration and initial development of other enabled devices which were to be the first “Smart Home” internet connected devices. Vosi needed a means for the system to communicate without a wired connection from the vehicle to the other devices in the network.
Bluetooth was chosen, since WiFi was not yet readily available or supported in the public market. Through the negotiations with Motorola, Vosi introduced and disclosed its intent to integrate Bluetooth in its devices.
In the early 2000s a legal battle ensued between Vosi and Motorola, which indefinitely suspended release of the devices. [23] This is in the globally unlicensed (but not unregulated) industrial, scientific and medical (ISM) 2.4 GHz short-range radio frequency band.
Since the introduction of Bluetooth 2.0+EDR, π/4-DQPSK (differential quadrature phase-shift keying) and 8-DPSK modulation may also be used between compatible devices. The term Enhanced Data Rate (EDR) is used to describe π/4-DPSK (EDR2) and 8-DPSK (EDR3) schemes, each giving 2 and 3 Mbit/s respectively. In 2019, Apple published an extension called HDR which supports data rates of 4 (HDR4) and 8 (HDR8) Mbit/s using π/4-DQPSK modulation on 4MHz channels with forward error correction (FEC) [1]. All devices within a given piconet use the clock provided by the master as the base for packet exchange.
The above excludes Bluetooth Low Energy, introduced in the 4.0 specification, which uses the same spectrum but somewhat differently. At any given time, data can be transferred between the master and one other device (except for the little-used broadcast mode). (m) (mW) (dBm) 1 100 20 ~100 1.5 10 10 ~20 2 2.5 4 ~10 3 1 0 ~1 4 0.5 −3 ~0.5 Source:BT 5 Vol 6 Part A Sect 3,Bluetooth Technology Website
Bluetooth is a standard wire-replacement communications protocol primarily designed for low power consumption, with a short range based on low-cost transceiver microchips in each device. [26] Because the devices use a radio (broadcast) communications system, they do not have to be in visual line of sight of each other; however, a quasi optical wireless path must be viable. Most Bluetooth applications are for indoor conditions, where attenuation of walls and signal fading due to signal reflections make the range far lower than specified line-of-sight ranges of the Bluetooth products. Adherence to profiles saves the time for transmitting the parameters anew before the bi-directional link becomes effective. There are a wide range of Bluetooth profiles that describe many different types of applications or use cases for devices.
This category of applications is sometimes called wireless local area networks (WLAN). Bluetooth serves well in simple applications where two devices need to connect with a minimal configuration like a button press, as in headsets and speakers.
Bluetooth exists in numerous products such as telephones, speakers, tablets, media players, robotics systems, laptops, and console gaming equipment as well as some high definition headsets, modems, hearing aids[47] and even watches. [48] Given the variety of devices which use the Bluetooth, coupled with the contemporary deprecation of headphone jacks by Apple, Google, and other companies, and the lack of regulation by the FCC, the technology is prone to interference.
While some desktop computers and most recent laptops come with a built-in Bluetooth radio, others require an external adapter, typically in the form of a small USB “dongle.” For Microsoft platforms, Windows XP Service Pack 2 and SP3 releases work natively with Bluetooth v1.1, v2.0 and v2.0+EDR. [53] Previous versions required users to install their Bluetooth adapter’s own drivers, which were not directly supported by Microsoft. [53] It is generally recommended to install the latest vendor driver and its associated stack to be able to use the Bluetooth device at its fullest extent.
The BlueZ stack is included with most Linux kernels and was originally developed by Qualcomm. [56] Fluoride, earlier known as Bluedroid is included in Android OS and was originally developed by Broadcom.
[63] A netgraph-based implementation from FreeBSD has also been available in the tree, possibly disabled until 2014-11-15, and may require more work. [67] It was established by Ericsson, IBM, Intel, Nokia and Toshiba, and later joined by many other companies.
Core Specification Addendum (CSA), release cycle can be as tight as a few times per year
Extended Synchronous Connections (eSCO), which improve voice quality of audio links by allowing retransmissions of corrupted packets, and may optionally increase audio latency to provide better concurrent data transfer. [71] EDR uses a combination of GFSK and phase-shift keying modulation (PSK) with two variants, π/4-DQPSK and 8-DPSK. [73] EDR can provide a lower power consumption through a reduced duty cycle.
Aside from EDR, the v2.0 specification contains other minor improvements, and products may claim compliance to “Bluetooth v2.0” without supporting the higher data rate. Version 2.1 allows various other improvements, including extended inquiry response (EIR), which provides more information during the inquiry procedure to allow better filtering of devices before connection; and sniff subrating, which reduces the power consumption in low-power mode. The Bluetooth radio is still used for device discovery, initial connection and profile configuration.
This means that Bluetooth uses proven low power connection models when the system is idle, and the faster radio when it must send large quantities of data.
It is intended for use by applications that require low latency between user action and reconnection/transmission of data. Enhanced power control removes the ambiguities by specifying the behavior that is expected. The feature also adds closed loop power control, meaning RSSI filtering can start as the response is received. WiMedia has transferred all current and future specifications, including work on future high-speed and power-optimized implementations, to the Bluetooth Special Interest Group (SIG), Wireless USB Promoter Group and the USB Implementers Forum.
After successful completion of the technology transfer, marketing, and related administrative items, the WiMedia Alliance ceased operations. A small, but significant, number of former WiMedia members had not and would not sign up to the necessary agreements for the IP transfer. As of 2009, the Bluetooth SIG was in the process of evaluating other options for its longer term roadmap. Chip designs allow for two types of implementation, dual-mode, single-mode and enhanced past versions.
In terms of lengthening the battery life of Bluetooth devices, BLE represents a significant progression. Cost-reduced single-mode chips, which enable highly integrated and compact devices, feature a lightweight Link Layer providing ultra-low power idle mode operation, simple device discovery, and reliable point-to-multipoint data transfer with advanced power-save and secure encrypted connections at the lowest possible cost. General improvements in version 4.0 include the changes necessary to facilitate BLE modes, as well the Generic Attribute Profile (GATT) and Security Manager (SM) services with AES Encryption.
Core Specification Addendum 2 was unveiled in December 2011; it contains improvements to the audio Host Controller Interface and to the High Speed (802.11) Protocol Adaptation Layer.
The update incorporates Bluetooth Core Specification Addenda (CSA 1, 2, 3 & 4) and adds new features that improve consumer usability. Notice that some features were already available in a Core Specification Addendum (CSA) before the release of v4.1.
Older Bluetooth hardware may receive 4.2 features such as Data Packet Length Extension and improved privacy via firmware updates. Sony was the first to announce Bluetooth 5.0 support with its Xperia XZ Premium in Feb 2017 during the Mobile World Congress 2017.
The increase in transmissions could be important for Internet of Things devices, where many nodes connect throughout a whole house. Minor Enhancements batch 1: HCI support for debug keys in LE Secure Connections Sleep clock accuracy update mechanism ADI field in scan response data Interaction between QoS and Flow Specification Block Host channel classification for secondary advertising Allow the SID to appear in scan response reports Specify the behavior when rules are violated BT LE Audio was announced in January 2020 at CES by the Bluetooth SIG. The hardware that makes up the Bluetooth device is made up of, logically, two parts; which may or may not be physically separate.
A radio device, responsible for modulating and transmitting the signal; and a digital controller. The Link Controller is responsible for the processing of the baseband and the management of ARQ and physical layer FEC protocols.
In addition, it handles the transfer functions (both asynchronous and synchronous), audio coding (e.g. SBC (codec)) and data encryption. To do this, the CPU runs software called Link Manager that has the function of communicating with other devices through the LMP protocol.
In addition, devices that communicate with Bluetooth almost universally can use these protocols: HCI and RFCOMM. One of the most important HCI tasks that must be performed is the automatic discovery of other Bluetooth devices that are within the coverage radius.
Only L2CAP channels configured in ERTM or SM may be operated over AMP logical links. Radio Frequency Communications (RFCOMM) is a cable replacement protocol used for generating a virtual serial data stream.
RFCOMM provides a simple, reliable, data stream to the user, similar to TCP. It is used directly by many telephony related profiles as a carrier for AT commands, as well as being a transport layer for OBEX over Bluetooth. Many Bluetooth applications use RFCOMM because of its widespread support and publicly available API on most operating systems. Its main purpose is the transmission of IP packets in the Personal Area Networking Profile.
In addition, packets with CRC will be retransmitted until acknowledged by automatic repeat request (ARQ). Technical information (for example: device features, manufacturer, Bluetooth specification used, clock offset) Most cellular phones and laptops show only the Bluetooth names and special programs are required to get additional information about remote devices.
At the same time, it is useful for Bluetooth devices to be able to establish a connection without user intervention (for example, as soon as in range). The pairing process is triggered either by a specific request from a user to generate a bond (for example, the user explicitly requests to “Add a Bluetooth device”), or it is triggered automatically when connecting to a service where (for the first time) the identity of a device is required for security purposes. During pairing, the two devices establish a relationship by creating a shared secret known as a link key.
Secure Simple Pairing uses a form of public-key cryptography, and some types can help protect against man in the middle, or MITM attacks. This method is typically used by headsets with minimal IO capabilities, and is more secure than the fixed PIN mechanism this limited set of devices uses for legacy pairing. This method provides MITM protection, assuming the user confirms on both devices and actually performs the comparison properly. Pairing is completed using the Bluetooth radio, but requires information from the OOB mechanism. Secure Simple Pairing uses a form of public-key cryptography, and some types can help protect against man in the middle, or MITM attacks. Using OOB with NFC enables pairing when devices simply get close, rather than requiring a lengthy discovery process.
Link keys may be stored on the device file system, not on the Bluetooth chip itself. Bluetooth implements confidentiality, authentication and key derivation with custom algorithms based on the SAFER+ block cipher. Those keys, used for subsequent encryption of data sent via the air interface, rely on the Bluetooth PIN, which has been entered into one or both devices. In September 2008, the National Institute of Standards and Technology (NIST) published a Guide to Bluetooth Security as a reference for organizations.
Users and organizations must evaluate their acceptable level of risk and incorporate security into the lifecycle of Bluetooth devices. In 2001, Jakobsson and Wetzel from Bell Laboratories discovered flaws in the Bluetooth pairing protocol and also pointed to vulnerabilities in the encryption scheme.
Digital Ltd. discovered that serious flaws in some poor implementations of Bluetooth security may lead to disclosure of personal data. [124] In a subsequent experiment, Martin Herfurt from the trifinite.group was able to do a field-trial at the CeBIT fairgrounds, showing the importance of the problem to the world. [125] In 2004 the first purported virus using Bluetooth to spread itself among mobile phones appeared on the Symbian OS. [126] The virus was first described by Kaspersky Lab and requires users to confirm the installation of unknown software before it can propagate.
Thus, it should be regarded as a potential (but not real) security threat to Bluetooth technology or Symbian OS since the virus has never spread outside of this system. [127] This poses a potential security threat because it enables attackers to access vulnerable Bluetooth devices from a distance beyond expectation.
The worm is self-installing and begins once the mobile user approves the transfer of the file (Velasco.sis) from another device. In April 2005, Cambridge University security researchers published results of their actual implementation of passive attacks against the PIN-based pairing between commercial Bluetooth devices. They confirmed that attacks are practicably fast, and the Bluetooth symmetric key establishment method is vulnerable. To rectify this vulnerability, they designed an implementation that showed that stronger, asymmetric key establishment is feasible for certain classes of devices, such as mobile phones.
In June 2005, Yaniv Shaked[131] and Avishai Wool[132] published a paper describing both passive and active methods for obtaining the PIN for a Bluetooth link. Also, this active attack probably requires custom hardware, since most commercially available Bluetooth devices are not capable of the timing necessary. In August 2005, police in Cambridgeshire, England, issued warnings about thieves using Bluetooth enabled phones to track other devices left in cars. Police are advising users to ensure that any mobile networking connections are de-activated if laptops and other devices are left in this way.
In April 2006, researchers from Secure Network and F-Secure published a report that warns of the large number of devices left in a visible state, and issued statistics on the spread of various Bluetooth services and the ease of spread of an eventual Bluetooth worm. In October 2006, at the Luxemburgish Hack.lu Security Conference, Kevin Finistere and Thierry Zoller demonstrated and released a remote root shell via Bluetooth on Mac OS X v10.3.9 and v10.4. They also demonstrated the first Bluetooth PIN and Linkkeys cracker, which is based on the research of Wool and Shaked. In April 2017, security researchers at Armis discovered multiple exploits in the Bluetooth software in various platforms, including Microsoft Windows, Linux, Apple iOS, and Google Android.
Armis contacted Google, Microsoft, Apple, Samsung and Linux developers allowing them to patch their software before the coordinated announcement of the vulnerabilities on 12 September 2017. Also, in October 2018, Karim Lounis, a network security researcher at Queen’s University, identified a security vulnerability, called CDV (Connection Dumping Vulnerability), on various Bluetooth devices that allows an attacker to tear down an existing Bluetooth connection and cause the deauthentication and disconnection of the involved devices. In August 2019, security researchers at the Singapore University of Technology and Design, Helmholtz Center for Information Security, and University of Oxford discovered a vulnerability in the key negotiation that would “brute force the negotiated encryption keys, decrypt the eavesdropped ciphertext, and inject valid encrypted messages (in real-time)”.
No specific harm has been demonstrated, even though wireless transmission has been included by IARC in the possible carcinogen list.
Even the maximum power output of class 1 is a lower level than the lowest-powered mobile phones. [146] The Breakthrough Awards[147] Bluetooth program highlights the most innovative products and applications available today, prototypes coming soon, and student-led projects in the making.
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