BLUETOOTH SECURITY

1. Introduction

From the beginning of the computer era, cables are being used to connect computers to each other and to special devices. For safe traveling of information security measures have been developed to secure the cable connections.

Now, as the time has change, cables are not of that much use, thus the Bluetooth is develop to provide cable-free environment. Bluetooth is a new technology named after the 10th century Danish king Harald Bluetooth.It is accepted as proposed standard for local wireless communication and is becoming more and more popular day by day. Now it is extended to support both the applications of voice/data access and personal ad hoc networks.

This blog gives information about the security measures of Bluetooth, where we examine the Bluetooth security architecture in detail, how they should be different from the old security measures of the cable-connected world and are they sufficient enough, so that Bluetooth can be used for everyday communications. I have given the Bluetooth security in two parts according to the framework proposed, including the build-in link-level Bluetooth security as the main part, and the service level Bluetooth security architecture as the practice part, respectively. And what possible uses it has.

1.1 APPLICATIONS

The Bluetooth works for the wide range of applications. These range from straightforward cable replacement to sophisticated networking applications.

Examples:

_ Wireless headsets for cell phones for hands-free, wire-free phone calls.

_ Wireless PC Mouse connection to the PC using Bluetooth.

_ Wireless printing between a PC or handheld and a Bluetooth enabled printer.

_ Wireless barcode scanner input for retail and warehousing.

_ Automated synchronization of Personal Digital Assistant (PDAs) and PCs using Bluetooth.

_ Ad hoc networking and file sharing between PCs, PDAs & laptops in a meeting.

_ Automated cell phone dialing from a laptop’s contact database with logging of the activity on the laptop.

_ Internet access for Bluetooth used devices via the Bluetooth enabled device on the Internet.

_ Synchronize contact information between a cell phone, PDA, notebook, and

desktop wirelessly.

_ With automatic synchronization enabled, everyone can see changes to the shared material on his or her own computer.

1.2 BENEFITS

The most basic benefit from Bluetooth is of simple cable replacement between two devices. For many situations were the physical elimination of inconvenient cables that take space and limit device placement. In industrial and commercial applications, the presence of wires creates problems and task interference issues. The wide range of device types and standard interface make by Bluetooth. Which allows selection of devices optimized each for their particular functions. The multi-point capabilities of Bluetooth communications allows one interface to support communications a set of wired and wireless devices are Bluetooth connectable, including office appliances, e.g. desktop PCs, printers, projectors, laptops, and PDAs; communication appliances, e.g. speakers, handsets, pagers, and mobile phones; home appliances, e.g. DVD players, digital cameras, cooking ovens, washing machines, refrigerators, and thermostats. Bluetooth is suitable for a wide range of applications, e.g. wireless office and meeting room, smart home and vehicle, intelligent parking, electrical paying and banking. printers, scanners, scales, PDAs, other PCs, etc.Bluetooth wireless networking, in general, provides a simple and fast path to ad hoc networks with minimal equipment and overhead.

2. Security Framework

The Bluetooth technology provides security at both the application layer and the link layer. In this there are two kinds of features that make attacks more difficult. A hop selection mechanism of up to 1600 hops/sec is used to avoid the interference from external or other piconets. An automatic output power adaptation scheme is also included in the standard for the low power consumption of light-weight mobile devices, which can reduce the radio spread range for data transmission exactly according to requirements based on the detected intensity.

2.1 Basic Definitions

A total of three different information security objectives are to be reached one or all. Confidentiality means that the data can only be used by authorized users and/or parties. Integrity means that the data cannot be modified during transfer and stored by adversaries. Availability means that the data is always available for authorized use.

Bluetooth gives three main techniques to achieve security features:

· Encryption: The process of transforming data into a form that it cannot be

understood without a key. Both data and control information can be encrypted.

· Authentication: means the ensuring of the identity of another user, so that he knows to whom is communicating with. In which to verify ‘who’ is at the other end of the link. Authentication is performed for both devices and users.

· Authorization: The process of deciding, if a device is allowed to have access to a service. Authorization always includes authentication.

2.2 Security Modes

Each Bluetooth device can work on one of the three security modes. Depending on whether a device uses a semi link key or a master key, there are several encryption modes available. If a unit key or a combination key is used, broadcast traffic is not encrypted. Individually addressed traffic can be either encrypted or not. If a master key is used, there are three possible modes.

In mode 1, is a non-secure mode, in which a Bluetooth device never initiates any security procedure, nothing is encrypted.

In mode 2, is service-level security where a device does not initiate security function before channel establishment and whether to initiate or not depends on the security requirements of the requested channel or service. Broadcast traffic is not encrypted, but the individually addressed traffic is encrypted with the master key.

In mode 3, is a link-level security in which a Bluetooth device shall initiate security function before the link set-up. All traffic is encrypted with the master key.

The above two levels of Bluetooth security scheme can be defined, as follows:

· Link-level security, The Bluetooth device initiates security functions before the channel is established. This is the in-built security mechanism.

· Service-level security, The Bluetooth device initiates security functions after the channel is established, i.e. at the higher layers.

2.3 Security Levels

Service-level security, The Bluetooth device initiates security functions after the channel is established, i.e. at the higher layers.Bluetooth allows different security levels to be used for devices and various services. To secure devices two security levels can be defined. An authorized device has unrestricted access to all or some specific services. Basically this means that the device has been previously authenticated is marked as “trusted”. An unauthorized device has restricted access to services. Usually the device has been previously authenticated but has not been marked as “trusted”. An unknown device is also an untrusted device.

Three levels of service security are used to be defined so that the requirements for authorization, authentication, and encryption can be set independently, including services that require authorization and authentication, services that require authentication only, and services open to all devices.

These three security levels can be described by using the following attributes:

· Authorization: The access services are granted only after an authorization procedure. Only authorized devices will get automatic access.

· Authentication: The remote device must be authenticated before being able to connect to the application being access.

· Encryption: the link between the two devices must be encrypted before the application can be accessed.

4. Service-level Security

This section gives basic issues involved in the implementation of security mechanisms; this is an approach for a flexible security architecture built on top of the link-level security features of Bluetooth. Figure 5 gives the general security architecture. The key component in the architecture is a security manager, with the following functions:

· Store security-related information on both services and devices into

corresponding service and device databases.

· Permit or refuse access requested by protocol implementations or applications.

· Command the link manager to enforce authentication and/or encryption before connecting to the application, using the HCI.

· Query Personal Identification Number (PIN) entry to set-up trusted device relationship.

Such a centralized security manager is flexible to implement different access strategy policies and easy to add new strategy without affecting other parts.

The security manager acts as a bridge to join application level and link level security controls together and thus helps in providing end-to-end security.

Authentication should be performed after determining what the security level of the requested service is. That is to say, the authentication can only be performed when a connection request to a service (SCO link) is submitted.