Just as important as the secure transmission of data over the air is the issue of data stored on your mobile device. Despite anti-virus software vendors' warnings, no serious viruses have spread to the mobile world as of the time of this writing. You can be sure, however, that mobile devices will catch the attention of virus developers as smart wireless devices proliferate and the value of data stored on those devices increases. A markup-based technology such as WAP would appear to be virus-proof, but technologies such as SMS can send text/multimedia messages to other users, and Java can dynamically download executable code to the device. While the Java 2 Micro Edition specification defines adequate security protections, bugs in the proliferation of virtual machines on a wide number of devices could open a Pandora's box of security problems. Companies such as McAfee are already offering anti-virus solutions for Palm OS, Windows CE, and EPOC in anticipation of a new wave of viruses.