Motorola MC55N0 User's Guide download pdf (Page 112)

5 - 2 MC55 User Guide

The Bluetooth radio in this MC55 operates as a Class 2 device power class. The maximum output power is 2.5mW

and the expected range is 32.8 feet (10 meters). A definition of ranges based on power class is difficult to obtain

due to power and device differences, and whether one measures open space or closed office space.

Security

The current Bluetooth specification defines security at the link level. Application-level security is not specified. This

allows application developers to define security mechanisms tailored to their specific need. Link-level security

occurs between devices, not users, while application-level security can be implemented on a per-user basis. The

Bluetooth specification defines security algorithms and procedures needed to authenticate devices, and if needed,

encrypt the data flowing on the link between the devices. Device authentication is a mandatory feature of Bluetooth

while link encryption is optional.

Pairing of Bluetooth devices is accomplished by creating an initialization key that is used to authenticate the

devices and create a link key for them. Entering a common PIN number in the devices being paired generates the

initialization key. The PIN number is never sent over the air. By default, the Bluetooth stack responds with no key

when a key is requested (it is up to user to respond to the key request event). Authentication of Bluetooth devices

is based-upon a challenge-response transaction. Bluetooth allows for a PIN number or passkey that is used to

create other 128-bit keys used for security and encryption. The encryption key is derived from the link key used to

authenticate the pairing devices. Also worthy of note is the limited range and fast frequency hopping of the

Bluetooth radios that makes long-distance eavesdropping difficult.

Recommendations are:

•

Perform pairing in a secure environment

•

Keep PIN codes private and don't store the PIN codes in the mobile computer

•

Implement application-level security.

The Microsoft stack supports Smart-pairing. For detailed information, refer to the Microsoft MSDN.

Security Mode 3 (Link Level Encryption)

The MC55 supports Security Level 3 (Link Level Encryption). Link level encryption is the data security process of

encrypting information at the data link level as it is transmitted between two devices.

Microsoft Bluetooth Stack

When pairing with a remote device using the Microsoft Bluetooth UI, Security Level 3 (Link Level Encryption) is

automatically used. When developing applications using the Microsoft Bluetooth stack, enable Security Mode 3

using the BthSetEncryption API call. Refer to the Microsoft MSDN for more information.

StoneStreet One Bluetooth Stack

To set Security Mode 3 on outgoing serial port connections, set Encrypt Link On All Outgoing Connections

checkbox in the Settings > Security tab. See Security Tab on page 5-32 for more information.

NOTE It is not recommended to perform Bluetooth wireless technology inquiry when high rate 802.11b operation is

required.

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Motorola MC55N0 User's Guide Page 112