How to win the clonewars: efficient periodic n-times anonymous authentication
Jan L. Camenisch, Susan Hohenberger, Markulf Kohlweiss, Anna Lysyanskaya, Mira Meyerovich · 2006
Abstract We create a credential system that lets a user anonymously authenticate at most n timesin a single time period. A user withdraws a dispenser of n e-tokens. She shows an e-token toa verifier to authenticate herself; each e-token can be used only once, however, the dispenser automatically refreshes every time period. The only prior solution to this problem, due toDamg*ard et al. [30], uses protocols that are a factor of k slower for the user and verifier, where kis the security parameter. Damg*ard et al. also only support one authentication per time period, while we support n. Because our construction is based on e-cash, we can use existing techniquesto identify a cheating user, trace all of her e-tokens, and revoke her dispensers. We also offer a new anonymity service: glitch protection for basically honest users who (occasionally) reuse e-tokens. The verifier can always recognize a reused e-token; however, we preserve the anonymity of users who do not reuse e-tokens too often. 1 Introduction As computer devices get smaller and less intrusive, it becomes possible to place them everywhere and use them to collect information about their environment. For example, with today's technology, sensors mounted on vehicles may report to a central traffic service which parts of the roads are treacherous, thus assisting people in planning their commutes. Some have proposed mounting sensors in refrigerators to report the consumption statistics of a household, thus aiding in public health studies, or even mounting them in people's bodies in an attempt to aid medical science. In all these areas, better information may ultimately lead to a better quality of life.