Chapter 2: Trends Towards Mobility 29 with unprotected PDAs, and then try to eavesdrop on the data traffi c or implant malicious software into unprotected devices. To avoid such risks, data encryption is a key function in wireless networks including WLAN, GSM, and Bluetooth. Compromising may take place passively without any malicious attacks. Simply the presence of a mobile device may suffi ce. For instance, some mobile phones allow access to their sharing media libraries through UPnP (Universal Plug and Play) networking over Blue- tooth. Sharing is disabled by default, but could be still left on without the user knowing it. Similarly, an attempt to print an image via Blue- tooth in a supermarket leaves a trace of the event in the shopkeeper’s devices. While personal content is not always too risky by its nature, it is nevertheless personal, and therefore merits protection. The Internet is, among other things, an instant massive distribution channel for per- sonal blunders. Consider the story of the “Star Wars Kid”, a schoolboy who recorded his vividly enacted light sabre exercises to video that then leaked into the Internet (Star Wars Kid 2003). The video spread instantly over the globe and was seen by millions of people. Had the boy known that his personal moments could spread so widely, he might have not recorded them at all, or kept them carefully to himself. Sadly, better data protection usually means decreased ease of use. The technologies and use conventions for the security of mobile per- sonal content are just starting to appear, so the compromises between usability and security are still being explored among mobile device designers. Meanwhile, the users are making their own solutions to mobile content security. The consensus could take a long time to develop. HANDS OFF MY FILES Angie is quite annoyed. They had come to this party at Joey’s, one of Eddie’s hacker friends. Besides computers, Joey was into DJing, and had found an interesting way to combine the two. Eddie explained to her how Joey’s sets were quite special: he invited people to bring their mobile phones and wireless music players, and then broke into them, digging out the music and playing it to everyone. Eddie seemed to think that was the neatest thing. Many people seemed to agree. The guys and gals were dancing to the beat with their hands in the air, going wild when a new mix began and someone shouted “That’s my song! Howd’ya do that!?” Joey just nodded his head, smiled enigmatically, and kept on clicking his PC while the tune pumped out of the speakers.