Furthermore, according to the paper "Threats to PDAs," by Symantec Corporation at http://www.symantec.com/sarc/avcenter/reference/malicious.threats.to.pdas.html, the operating systems of handheld devices provide "libraries to applications to easily establish a connection with any other machine on the Internet and transfer data to and from that machine using the standard TCP/IP protocols." Although currently only 5-10% of all handheld users worldwide have wireless access, the number of people who own wireless handheld devices is expected to increase to 40% in 2004.

Software solutions
Software solutions provide a way to protect PDAs against viruses that have been or will be delivered through one or more points of entry. Anti-virus software solutions utilize either a database or a behavioral method of protection.

In this article, we'll perform a critical comparison of four products offered by McAfee Corporation (at http://www.mcafee.com), Symantec Corporation (at http://www.symantec.com), and Finjan Software (at http://www.finjan.com). All of the vendors' products will be analyzed based on the criteria of effectiveness, durability, size restriction, release date, price, ease of use, and company reputation. The scoring works as follows:

• Effectiveness scores how many methods of virus delivery (i.e., synchronizing, infrared beaming, and network access) the software works to protect against. One point will be given for every method protected against.

• Durability evaluates the length of time before the software needs to be maintained to protect against new viruses. Products that are proactive in detecting future viruses will be given a three. Conversely, products that are reactive will be given a one because they require updates.

• Size restriction considers the software file size in relation to the file space on the device. This is an important criterion due to the limited space on a PDA.

• Release date refers to the date a full-version of the product first became available. Products with earlier release dates will be ranked higher because of increased consumer evaluation and subsequent revisions.

• Price is the estimated or suggested retail price for each product.

• Ease of use describes how uncomplicated the software is to install, configure, and update. Products that are easier to use will be given higher scores.

• Company reputation, though weighted the lowest, is still relevant (though subjective) because a reputable company is more likely to produce a product that consumers feel is reliable and trusted.

Based on the above criteria, the anti-virus product receiving the highest total score will be deemed the best solution.

Database solutions
Database solutions use a database of known virus signatures that can be identified by characteristic byte patterns. When the anti-virus program is run, these specific byte patterns are compared to files, boot records, memory, and other locations where executable code is stored to see if any viruses are present. When new viruses are created and discovered, anti-virus companies create patches and updates for the databases to distribute to customers. Database solutions have traditionally been used for desktop computers and are now being used for PDAs. Anti-virus programs of this type are very effective at catching viruses that are defined in their databases. However, the database method has two limitations when used with Palm devices.