Sunday, July 14, 2002: 6:00 pm (Area "B"): They're used everywhere but they could be making you even more vulnerable to privacy invasion. Delchi has been working with proximity based card systems for two years and has developed a method of casually extracting data from proximity cards in a public environment. Riding in an elevator, subway, or just walking down the hall, a person can bump into you, say "excuse me," and walk away with the decoded information from the proximity card in your pocket. It could then be possible to build a device that can capture and replay these snippets of information on demand or to even brute force a proximity card system. This talk will focus on the vulnerabilities of the systems and show a low power working prototype. Alternatives will be discussed, as well as other vulnerable aspects of proximity based building and computer access systems.