Computer Science Research Seminar

11:30 am - 12:30 pm, Wednesday, October 21, 2009

Prof. Nelly Fazio

CUNY/City College & Graduate Center

Title: Threshold Signatures with Efficient Key Redistribution


In this talk, I will focus on the problem of authenticated communication in dynamic federated environments. Our approach extends the conventional threshold signature paradigm by additionally supporting membership changes to the federated system: While traditional systems split the signature key only among an a priori fixed group, our scheme allows evolving membership by repeatedly and securely (re)distributing key shares from the old set of key-holders to the new set of agents. This is realized without resorting to system re-initialization nor relying on a central trusted dealer.


Nelly Fazio joined the Department of Computer Science at CUNY/City College & Graduate Center as an Assistant Professor in September 2008. Since then, she is also a member of the research Center for Algorithms and Interactive Scientific Software (CAISS) at CCNY. Before joining CUNY, she was a visiting research scientist in the Security group at IBM T.J. Watson Research center, working on security issues of decentralized environments such as mobile ad-hoc networks (MANETs) and sensor networks. Prior to that, she was a postdoctoral researcher in the Content Protection group at IBM Almaden Research Center, where she conducted research on advanced cryptographic key management, tracing technologies, and authenticated communication in dynamic federated environments.

Dr. Fazio's research interests are in cryptography and information security, with a focus on digital content protection. She earned her M.Sc.('03) and Ph.D.('06) in Computer Science from New York University. In 2003, she was awarded the NYU CIMS Sandra Bleistein prize, for "notable achievement by a woman in Applied Mathematics or Computer Science." Her Ph.D. thesis was nominated with honorable mention for the NYU J. Fabri prize, awarded yearly for the "most outstanding dissertation in Computer Science."

For more information about this colloquium, please contact Habib M. Ammari at