Why mix Bluetooth with Wi-Fi?

* Security for Bluetooth beats that for ad hoc Wi-Fi mode

When the latest version of Bluetooth was announced last week, two questions popped to mind. First, what does Bluetooth 3.0 - which combines the Bluetooth wireless communications protocol with 802.11g Wi-Fi transport capabilities - offer that plain old Wi-Fi doesn't? Second, how are 3.0 connections secured, given that Wi-Fi running in ad hoc (peer-to-peer) mode hasn't historically received many kudos for privacy? It turns out that the two questions and their answers are somewhat related.

Let’s look at the first question: Why combine the two technologies, rather than just using the one with the faster transport (Wi-Fi) to begin with?

One reason is that about 40 peer-to-peer applications, a.k.a. profiles, have already been built right into many Bluetooth certified products. The Bluetooth Special Interest Group charter includes standardizing applications, such as file transfer, audio distribution, printing, synchronization, and so forth, while the IEEE 802.11 task groups and the Wi-Fi Alliance charters do not. Bottom line, there are some existing, useful Bluetooth applications already kicking around that could benefit from a heftier transmission speed.

Ironically, when comparing the two technologies in peer-to-peer mode, it also turns out that Bluetooth has a security leg up on Wi-Fi. Bluetooth 3.0 simply doesn’t allow transmissions to be sent in the clear, explains Kevin Hayes, a Fellow at wireless chip maker Atheros and lead technical editor of the 802.11 portion of the Bluetooth 3.0 spec. Ad hoc Wi-Fi connections, however, do support these inherently insecure modes. Though ad hoc Wi-Fi has gained a Robust Security Networking (RSN) mode that is essentially WPA2, it still works in the clear by default and “is what most people use because they don’t know how to turn on security,” Hayes says.

I was assuming that, since Bluetooth operates in peer-to-peer mode, it would use the Wi-Fi ad hoc (peer-to-peer) transmission method. Well, you know what happens when you “assume.” Rather, Bluetooth 3.0 uses the traditional hybrid client/AP mode of connection, secured, in effect, by the 802.11i AES-CCMP encryption algorithm over the air, Hayes says.

Copyright © 2009 IDG Communications, Inc.

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