Michael J Freedman, the NYU graduate student, will be speaking on Monday at 1:30 in room 402. His talk title and abstract are included below. If you'd like to talk with him, please sign up in /n/fs/department/schedules/visitors/visitfall06/freedman Just to avoid some confusion that occurred the last time he visited, please note that this is not Michael H. Freedman, the Fields Medal winner. =================== RE: Fighting Spam with Reliability and Privacy Mike Freedman NYU / Stanford http://www.scs.stanford.edu/mfreed/ mfreed@scs.stanford.edu ----- The explosive growth in unwanted email has prompted the development of techniques for the rejection of email, intended to shield recipients from the onerous task of identifying the legitimate email in their inboxes amid a sea of spam. Unfortunately, widely-used content-based filtering systems have converted the spam problem into a false positive one: Email has become unreliable. We present Reliable Email (RE: [1]), a new whitelisting system that incurs zero false positives among socially-connected users yet populates whitelists automatically by exploiting transitive trust relationships. Further, while RE: permits a recipient to discover whether other users have whitelisted the sender, it preserves the privacy of email contacts with a cryptographic Private Matching [2] protocol. Using real email traces from two sites, we demonstrate that RE: renders a significant fraction of received email reliable. Our evaluation also shows that RE: can prevent up to 88% of the false positives incurred by common email rejection systems. Finally, we propose a more formal definition of security for verifying social connectedness in a privacy-preserving fashion [3]. In the process, we identify a mismatch between RE:'s goals and [2]'s properties, enabling us to construct new cryptographic protocols that are either more efficient (based only on symmetric operations) or achieve stronger guarantees (namely, non-transferability) through bilinear pairings. Using such, RE: can provide privacy-preserving social whitelisting with millisecond overhead. 1. Re: Reliable Email Garriss, Kaminsky, Freedman, Karp, Mazieres, and Yu, NSDI '06 2. Efficient Private Matching and Set Intersection Freedman, Nissim, and Pinkas, EUROCRYPT '04 3. Efficient Private Techniques for Verifying Social Proximity Freedman and Nicolosi, Submitted Nov '06 ----- Michael J. Freedman is a doctoral student at NYU, currently visiting Stanford University. He received his M.Eng. and S.B. degrees from MIT. His research interests broadly focus on security, distributed systems, and cryptography. Among other things, he developed the Coral content distribution network and OASIS anycast service, which serve more than a million users daily (see www.coralcdn.org). In 2006, he co-founded Illuminics Systems, which has been acquired by Quova, Inc.