Everyone is looking for our trust at the moment. Schemes for digitally signing applications seem to be popping up like gophers across the mobile landscape, each of them confident that we'll place our trust in their authority. Microsoft, of course, has been trying to convince us to only trust applications and drivers signed by them on our desktops. Now Symbian will be signing applications for our phones while Nokia has launched their own scheme (called "Nokia OK") to demonstrate that the application meets with their approval.

While the lack of granular security in Symbian (once an application is running it can do anything) might make certification useful, Sun reckons that network operators would like to see their approval on Java applications (which generally don't have the same security issues), while the networks themselves are already preparing their own offerings.

So what will all these certificates tell us? Are any of these parties actually willing to take some responsibility for the application when things go wrong? When your digitally signed game starts sending out spam text messages to everyone in your address book will you have someone to sue? It seems not; while all these companies are happy to lend their names to say that the applications work properly, no one appears to be happy to accept the liability when it turns out they don't. Ultimately it's the network operators who will have to deal with irate customers, and blaming them for installing software (the normal defense in desktop support) isn't going to wash. Flashing warnings on the screen just doesn't work, as the recent My Doom and Bagel worms amply demonstrate; users will click "OK" no matter how many times they are told to take care, and it's not practical to educate all mobile phone users in the intricacies of device security.

BREW provides one alternative to pointless dialogs for the user to agree with; it just won't allow users to install an application unless QUALCOMM, or its partners, has approved that application. While that might seem draconian, it will be BREW users who are laughing when the first Symbian worm strikes.

With MIDP 2.0, the latest version of Java, applications are divided into domains including "vendor," "operator," and "trusted third party" with access to different APIs being restricted by who digitally signed the application. When messages are displayed to the user they are clear and action-related, such as: "This application wants to send a text message." The user is then free to make an informed choice to allow or disallow the action. Users understand actions, and an application that misbehaves will be given short shift. This mechanism allows informed choices from the users, while protecting them, and their network, from undue interference. But even this approach is fraught with problems. How do the certificates get onto the phone? What happens if a user changes networks? When an application manages to bypass this security who will be liable (Sun, the network, or the JVM vendor)?

A mobile phone is not a desktop computer, and the security it needs isn't the same. The sooner people start to recognize that fact the better.

Someone else asked me to trust them the other day, someone I had never met and will probably never meet. I was traveling on the subway, reading some documents on my Palm, when up popped a message saying that "Pug Ugly" was trying to connect and did I want to allow them. This was, obviously, a Bluetooth connection and I simply rejected it and continued reading. It seems that Mr. Ugly was a persistent soul, and tried another few times before I switched off my Bluetooth connectivity to be able to read in peace. I had heard about this use of Bluetooth (Bluejacking, as it's known), and while some Nokia handsets have had security issues, in general I leave all my devices advertising their presence and consider such approaches no different from someone walking up to me and talking. It occurred to me that I'm something of a gold mine for anyone playing with a new Bluetooth device, because I carry at least three active devices at any time. People sharing a carriage with me must think Bluetooth is everywhere.

Glancing around the carriage, I noticed a girl surreptitiously keying a Nokia 3650 and could only assume that the identity of Mr. Ugly had been established (though to be fair, the girl was neither Mr. nor Ugly). Checking my P900 later, I discovered dozens of messages sent over a period of months including graphics (like the skeleton pictured) and sounds. I've said several times that the best way to get users comfortable with a technology is to provide a silly application for it, the sillier the better. By playing with Bluetooth, users can gain confidence with this new wireless technology, so when they want a way to connect things together it's the obvious choice. Other than mobile telephones, wireless is still a novelty to most people, making this the perfect time to have some fun with it.