What is Bluetooth?
Bluetooth is an industrial specification
for wireless personal area networks (PANs).
Bluetooth provides a way to connect and exchange
information between devices such as mobile phones,
laptops, PCs, printers, digital cameras and video
game consoles over a secure, globally unlicensed
short-range radio frequency.
Who developed
Bluetooth?
Developed originally by Ericsson the specification
was adapted by the Bluetooth Special Interest Group
(SIG) in 1999 as an open industrial standard for
wireless PANs.
Bluetooth was named after a 10th century king,
Harald Bluetooth King of Denmark and Norway.
How do Blutooth
devices communicate?
A Bluetooth device playing the role of
“Master” can connect and communicate with up to 7
devices playing the role of “Slave”. At any given
time data can be transmitted between the Master and
one Slave, however the Master can switch rapidly
from Slave to Slave in a round-robin fashion.
Several communication protocols have been
standardized by SIG, the most commonly used for
mobile phone applications being the Headset Profile
(HSP) and the Hands Free Profile (HFP).
The HSP is the widely used protocol, enabling
Bluetooth headsets to communicate with mobile
phones. Normal controls include the ability to ring,
answer a call, hang up and adjust the volume.
The HFP protocol is considered a Killer Application
for Bluetooth (a program that is so useful that
people will buy a particular device simply to run
that program) and is the most widely used protocol
to connect mobile phones with Bluetooth hands-free
car kits, like EGO. It uses synchronous connection
to transmit data.
Is Bluetooth
secure?
Bluetooth implements authentication and key
derivation with custom algorithms based on the
SAFER+ block cipher. The initialization key and
master key are generated with the E22 algorithm. The
E0 stream cipher is used for encrypting packets.
This makes eavesdropping on EGO hands-free car kits
impossible.
How do Bluetooth
devices know each other?
Pairs of devices may establish a trusted
relationship by learning (by user input) a shared
secret known as a passkey. A device that wants to
communicate only with a trusted device can
cryptographically authenticate the identity of the
other device. Trusted devices may also encrypt the
data that they exchange over the air so that no one
can listen in. The encryption can, however, be
turned off, and passkeys are stored on the device
file system, not on the Bluetooth chip itself. Since
the Bluetooth address is permanent, a pairing is
preserved, even if the Bluetooth name is changed.
Pairs can be deleted at any time by either device.
Devices generally require pairing or prompt the
owner before they allow a remote device to use any
or most of their services.
More information about Bluetooth can be found on
Wikipedia.
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