BLUETOOTH TECHNOLOGY/SECURITYPrepared By: Lo’ai Hattar

Supervised By: Dr. Lo’ai Tawalbeh

New York Institute of Technology (NYIT)Jordan’s campus-2006

What’s With the Name?

•The name ‘Bluetooth’ was named after 10th century Viking king in Denmark Harald Bluetooth who united and controlled Denmark and Norway.

•The name was adopted because Bluetooth wireless technology is expected to unify the telecommunications and computing industries

Who Started Bluetooth?

• Bluetooth Special Interest Group (SIG)

•Founded in Spring 1998

•By Ericsson, Intel, IBM, Nokia, Toshiba;

•Now more than 2000 organizations joint the SIG

What Is Bluetooth?☼ Bluetooth is an open standard for short-range digital radio to interconnect a variety of devices Cell phones, PDA, notebook computers, modems, cordless phones, pagers, laptop computers, printers, cameras by developing a single-chip, low-cost, radio-based wireless network technology

Bluetooth

• Simplifying communications between: - devices and the internet- data synchronization

• Operates in licensed exempt ISM band at 2.4ghz• Uses frequency hoping spread spectrum• Omni directional, no requiring line of sight • Bluetooth offers data speeds of up to 1 Mbps up to 10

meters (Short range wireless radio technology )• Unlike IrDA, Bluetooth supports a LAN-like mode

where multiple devices can interact with each other.• The key limitations of Bluetooth are security and

interference with wireless LANs. • Short range wireless radio technology

Bluetooth

• Bluetooth is a PAN Technology– Offers fast and reliable transmission for

both voice and data– Can support either one asynchronous data

channel with up to three simultaneous synchronous speech channels or one channel that transfers asynchronous data and synchronous speech simultaneously

– Support both packet-switching and circuit-switching

Bluetooth

• Personal Area Network (PAN) Bluetooth is a standard that will …– Eliminate wires and cables between both

stationary and mobile devices– Facilitate both data and voice

communications– Offer the possibility of ad hoc networks and

deliver synchronicity between personal devices

Bluetooth Topology

• Bluetooth-enabled devices can automatically locate each other

• Topology is established on a temporary and random basis

• Up to eight Bluetooth devices may be networked together in a master-slave relationship to form a Piconet

Cont.

• One is master, which controls and setup the network

• All devices operate on the same channel and follow the same frequency hopping sequence

• Two or more piconet interconnected to form a scatter net

• Only one master for each piconet• A device can’t be masters for two piconets• The slave of one piconet can be the master of

another piconet

Ad-hoc• is a network connection method which is most often

associated with wireless devices. • The connection is established for the duration of one

session and requires no base station. • Instead, devices discover others within range to form a

network for those computers. • Devices may search for target nodes that are out of range

by flooding the network with broadcasts that are forwarded by each node.

• Connections are possible over multiple nodes (multihop ad hoc network).

• Routing protocols then provide stable connections even if nodes are moving around

A piconet

• is an ad-hoc computer network of devices using Bluetooth technology protocols to allow one master device to interconnect with up to seven active slave devices

• Up to 255 further slave devices can be inactive, or parked, which the master device can bring into active status at any time.

A Typical Bluetooth Network Piconet

• Master sends its globally unique 48-bit id and clock– Hopping pattern is determined by the 48-bit device ID– Phase is determined by the master’s clock

• Why at most 7 slaves?– (because a three-bit MAC adress is used).

• Parked and standby nodes– Parked devices can not actively participate in the

piconet but are known to the network and can be reactivated within some milliseconds

– 8-bit for parked nodes– No id for standby nodes– Standby nodes do not participate in the piconet

Security Protocol

• There are five phases of Simple Pairing:Phase 1: Public key exchangePhase 2: Authentication Stage 1Phase 3: Authentication Stage 2Phase 4: Link key calculationPhase 5: LMP Authentication and Encryption• Phases 1, 3, 4 and 5 are the same for all protocols

whereas phase 2 (Authentication Stage 1) is different depending on

• the protocol used. Distributed through these five phases are 13 steps.

Bluetooth Frequency

• Has been set aside by the ISM( industrial ,sientific and medical ) for exclusive use of Bluetooth wireless products

• Communicates on the 2.45 GHz frequency

Frequency Selection

• FH is used for interference mitigation and media access;

• TDD (Test-Driven Development) is used for separation of the transmission directions In 3-slot or 5-slot packets

FH-CDMA (Frequency Hopping - Code Division Multiple Access)

• Frequency hopping (FH) is one of two basic modulation techniques used in spread spectrum signal transmission.

• It is the repeated switching of frequencies during radio transmission, often to minimize the effectiveness of the unauthorized interception or jamming of telecommunications.

• It also is known as frequency- hopping code division multiple access (FH-CDMA).

• Bluetooth uses a technique called spread-spectrum frequency hopping.

Avoiding Interference : Hopping•

• In this technique, a device will use 79 individual, randomly chosen frequencies within a designated range

• Transmitters change frequency 1600 times a second

Cont.

• Each channel is divided into time slots 625 microseconds long

• Data in a packet can be up to 2,745 bits in length

• Packets can be up to five time slots wide

Cont. • FH-CDMA to separate piconets within a scatternet

• More piconets within a scatter net degrades performance– Possible collision because hopping patterns are

not coordinated

• At any instant of time, a device can participate only in one piconet

• If the device participates as a slave, it just synchronize with the master’s hop sequence

Cont.

• The master for a piconet can join another piconet as a slave; in this case, all communication within in the former piconet will be suspended .

• When leaving a piconet, a slave notifies the master about its absence for certain amount of time.

• Communication between different piconets takes place by devices jumping back and forth between these nets

Simplified Bluetooth stack

Bluetooth Profile Structure

How Does It Work?

• Bluetooth is a standard for tiny, radio frequency chips that can be plugged into your devices

• The information is then transmitted to your device

• These chips were designed to take all of the information that your wires normally send, and transmit it at a special

frequency to something called a receiver

Bluetooth chip.

Bluetooth Chip

RFBaseband

Controller

Link

Manager

Bluetooth Chip

SPECIFICATIONS

• Bluetooth specifications are divided into two:– Core Specifications

This bluetooth specification contains the Bluetooth Radio Specification as well as the Baseband, Link Manager, L2CAP, Service Discovery, RFCOMM and other specifications.

SPECIFICATIONS

– Application Specifications• These specifications include the following• Profiles Cordless Telephony• Serial Port• Headset• Intercom• Dialup Networking• Fax• File Transfer• Service Discovery Application• Generic Access

RADIO POWER CLASSES

• The Bluetooth specification allows for three different types of radio powers:

– Class 1 = 100mW

– Class2 = 2.5mW

– Class 3 = 1mW

• These power classes allow Bluetooth devices to connect at different ranges

• High power radius have longer ranges. The maximum range for a Class 1, 100mW is about 100 meters. There is also a minimum range for a Bluetooth connection. The minimum range is around 10cm.

Power Management Benefits

• Cable Replacement– Replace the cables for peripheral devices

• Ease of file sharing– Panel discussion, conference, etc.

• Wireless synchronization– Synchronize personal information contained in the address

books and date books between different devices such as PDAs, cell phones, etc.

• Bridging of networks– Cell phone connects to the network through dial-up

connection while connecting to a laptop with Bluetooth.

Bluetooth Devices

• Telephones• Headsets • Computers• Cameras• PDAs• Cars• Etc …

Bluetooth will soon be enabled in everything from:

Bluetooth Products 1

• Bluetooth-enabled PC Card

Bluetooth Products 2

• Bluetooth-enabled PDA

Bluetooth Products 3

• Bluetooth-enabled Cell Phone

Bluetooth Products 4

• Bluetooth-enabled Head Set

Usage Models• Cordless computer

• Ultimate headset

• Three-in-one phone

• Interactive conference (file transfer)

• Direct network access

• Instant postcard

Wireless Technologies

• There are two technologies that have been developed as wireless cable replacements: Infrared (IRDA) and radio (Bluetooth).

Why Not Infrared?• Intended for point to point links• Limited to line of sight• have a narrow angle (30 degree cone),• Low penetration power• Distance covered is low(1 meter approx)• have a throughput of 9600 bps to 4 Mbps • IrDA has proven to be a popular technology with

compliant ports currently available in an array of devices including: embedded devices, phones, modems, computers (PCs) and laptops, PDAs, printers, and other computer peripherals

Compare Infrared, Bluetooth

Bluetooth Infrared

Connection Type

Spread Spectrum

Infrared, narrow beam

Spectrum 2.4GHz Optical 850 nano meters

Data Rate 1Mbps 16Mbps

Range 30 Feet 3 Feet

Supported Devices

Upto 8 2

Cont…..

Voice Channels

3 1

Data Security 8-128bit KeyNo special

security

Addressing 48 bit MAC 32 bit ID

Our Focus

•Bluetooth security

Security of Bluetooth

• Security in Bluetooth is provided on the radio paths only– Link authentication and encryption may be provided– True end-to-end security relies on higher layer security

solutions on top of Bluetooth

• Bluetooth provides three security services– Authentication – identity verification of communicating devices– Confidentiality – against information compromise– Authorization – access right of resources/services

• Fast FH together with link radio link power control provide protection from eavesdropping and malicious access– Fast FH makes it harder to lock the frequency– Power control forces the adversary to be in relatively close

proximity

Security Modes (Authentication )

• Exchange Business Cards– Needs a secret key

• A security manager controls access to services and to devices– Security mode 2 does not provide any security

until a channel has been established

• Key Generation from PIN– PIN: 1-16 bytes. PINs are fixed and may be

permanently stored. Many users use the four digit 0000

Bluetooth Key Generation From PIN

• Bluetooth Initialization Procedure (Pairing)– Creation of an initialization key (ki)

– Creation of a link key Authentication (ka)

Creation of an Initialization Key

• PIN and its length (ki)

Creation of a link key Authentication

• Challenge-Response Based– Claimant: intends to prove its identity, to be verified– Verifier: validating the identity of another device– Use challenge-response to verify whether the claimant

knows the secret (link key) or not . If fail, the claimant must wait for an interval to try a new attempt.

– The waiting time is increased exponentially to defend the “try-and-error” authentication attack

– Mutual authentication is supported• Challenge (128-bit)• Response (32-bit)• 48-bit device address

Confidentiality

• ACO (Authenticated Cipher Offset) is 96-bit,

generated during the authentication procedure– ACO and the link key are never transmitted

• Encryption key Kc is generated from the current link key– Kc is 8-bit to 128-bit, negotiable between the master

and the slave Master suggests a key size Set the “minimum acceptable” key size parameter to prevent a malicious user from driving the key size down to the minimum of 8 bits

• The key stream is different for different packet since slot number is different

Three Encryption Modes for Confidentiality

• Encryption Mode 1: -- No encryption is performed on any traffic

• Encryption Mode 2: -- Broadcast traffic goes unprotected– while uni cast traffic is protected by the unique

key

• Encryption Mode 3: -- All traffic is encrypted

Trust Levels, Service Levels(authorization )

• Two trust levels: trusted and untrusted

– Trusted devices have full access right

– Untrusted devices have restricted service access

Bluetooth Security Architecture

• Step 1: User input (initialization or pairing)– Two devices need a common pin (1-16 bytes)

• Step 2: Authentication key (128-bit link key) generation– Possibly permanent, generated based on the PIN, device

address, random numbers, etc.

• Step 3: Encryption key (128 bits, store temporarily)

• Step 4: key stream generation for xor-ing the payload

Security cont.

• The security of the whole system relies on the PIN which may be too short– Users intend to use 4-digit short PINs, or even a

null PIN

• Utilized new cryptographic primitives, which have not gone through enough security analysis. (E0,E1,E20,E22) algorithms

E0 algorithm

• The E0 algorithm is designed specifically for Bluetooth

• E0 has gone many security analysis. When used in Bluetooth mode, the security of E0 is decreased from 128-bit to 84-bit;

• when used outside of a Bluetooth system, its effective security is only 39-bit

• A Bluetooth device resets the E0 key after every 240 output bits, severely limiting the amount of known key stream that may be available to the cryptanalyst.

Short Key Attacks

• we focus on .short key. attacks, that still manage to recover the key despite this limitation.

• attacker can guess the content of the registers of the three smaller LFSRs and of the E0 combiner state registers with a probability of 2 to power 93.

• This attack requires a total of 128 bits of known plaintext and ciphertext. The reverse engineering and verication takes approximately 27 operations. Making the total complexity of the attack 2to power100.

Long Key Attacks

• an attack that recovers the session key in a similar way to what showed, only that assuming much more keystream is available

• within a packet and therefore the overall complexity was closer to O(2 to power 93).

• Short range was a countermeasure to force the attackers to be in close proximity; – now range extenders can be easily built

• Attackers grow since information is more attractive– People use Bluetooth not only for personal

information, but also for corporate information

Hacker Tools

• Bluesnarfing:• is the theft of information from a wireless device through

a Bluetooth connection. • By exploiting a vulnerability in the way Bluetooth is

implemented on a mobile phone, an attacker can access information -- such as the user's calendar, contact list and e-mail and text messages -- without leaving any evidence of the attack.

• Other devices that use Bluetooth, such as laptop computers, may also be vulnerable, although to a lesser extent, by virtue of their more complex systems.

• Operating in invisible mode protects some devices, but others are vulnerable as long as Bluetooth is enabled.

Hacker Tools

• Bluejacking • is the sending of unsolicited messages over Bluetooth to

Bluetooth-enabled devices such as mobile phones, PDAs or laptop computers, sending a vCard which typically contains a message in the name field It is widely believed that the term bluejacking comes from Bluetooth and hijacking.

• However, a bluejacker doesn't hijack anything: he or she merely uses a feature on the sender and the recipient's device. Both parties remain in absolute control over their devices, and a bluejacker will not be able to take over your phone or steal your personal information.

• Bluejacking is usually technically harmless, but because bluejacked people don't know what is happening, they think their phone is malfunctioning.

• Usually, a bluejacker will only send a text message, but with modern phones it's possible to send images or sounds as well.

Most important security weaknesses

• Problems with E0

• PIN

• Problems with E1

• Location privacy

• Denial of service attacks

Problems with E0

• Given all cryptographic primitives (E0, E1, E21, E22) used in Bluetooth Pairing/Bonding and authentication process the Bluetooth PIN can be cracked ? – Focus on short PIN now.

• Output (KC) = combination of 4 LFSRs (Linear Feedback Shift Register)

• Key (KC) = 128 bits

• Best attack: guess some registers

PIN

• Some devices use a fixed PIN (default=0000)

• Security keys = security PIN !!!!

• Possible to check guesses of PIN (SRES) -> brut force attack

• Weak PINs (1234, 5555, …

Problems with E1

• E1 = SAFER+• In cryptography, SAFER (Secure And Fast Encryption

Routine) is the name of a family of block ciphers The early SAFER K and SAFER SK designs share the same encryption function, but differ in the number of rounds and the key schedule. More recent versions — SAFER+ and SAFER++ —

• All of the algorithms in the SAFER family are unpatented and available for unrestricted use.

• Some security weaknesses (although not applicable to Bluetooth)– slow

Location privacy

• Devices can be in discoverable mode

• Every device has fixed hardware address Addresses are sent in clear

– possible to track devices (and users)

Denial of service attacks

• Radio jamming attacks

• Buffer overflow attacks

• Blocking of other devices

• Battery exhaustion (e.g., sleep deprivation torture attack)

Other weaknesses

• No integrity checks

• No prevention of replay attacks

• Man in the middle attacks

• Sometimes: default = no security

Advantages (+)

• Wireless (No Cables)

• No Setup Needed

• Low Power Consumption (1 Milliwat)

• Industry Wide Support

Disadvantages (-)

• Short range (10 meters)

• Small throughput rates

- Data Rate 1.0 Mbps

• Mostly for personal use (PANs)

• Fairly Expensive

Bluetooth’s Future•The future of this technology becoming a standard is likely

•With a strong industry pushing behind it, success is inevitable.

•Often, with new technology, early changes mean reconstruction. Not With Bluetooth, instead, there will be an improvement to the existing standard.

•Bluetooth will soon be known as Bluetooth 2.2 as they are trying to develop the product to better fulfill the needs of consumers

The End

• Thank You, for attending my presentation.