Functional Secret Sharing
Functional encryption is now receiving a lot of attention. However, the topic of functional encryption was preceded by functional secret sharing (SIAM Journal on Discrete Mathematics, 2000). In this lecture, we explain some of the motivations behind functional secret sharing. We note that in functional secret sharing, we have, as in normal secret sharing, a dealer. However, after the participants received shares from the dealer, a function f will be chosen and the participants will be asked to evaluate f(secret), without any help of the dealer. Two approaches are surveyed. The first one is non-interactive in the sense that the participants need to broadcast some partial evaluation of f(secret). Since broadcast is used, these partial evaluations should not facilitate a non-authorized set to compute f'(secret), except if f'(secret) follows logically from f(secret). The second approach is interactive in which stricter privacy requirements can be enforced. Most of our solutions are reusable. We conclude with giving open problems.
Yvo Desmedt is the Jonsson Distinguished Professor at the University of Texas at Dallas, a courtesy chair at the University College London and a Fellow of the International Association of Cryptologic Research (IACR). He received his Ph.D. (1984, Summa cum Laude) from the University of Leuven, Belgium. He received the IBM Belgium Prize for best PhD in Computer Science that year. He held positions at: Universite de Montreal, University of Wisconsin - Milwaukee (founding director of the Center for Cryptography, Computer and Network Security), and Florida State University (Director of the Laboratory of Security and Assurance in Information Technology, an NSA Center of Excellence since 2000). He has held visiting appointments at AIST (Japan), Macquarie University (Australia), Technion (Israel), Tokyo Institute of Technology (Japan), University of Karlsruhe (Germany), among others. He is an (associate) editor of The Journal of Computer Security and Editor-in-Chief of IET Information Security and Chair of the Steering Committees of CANS and ICITS. He was/is Program Chair of Crypto 1994, the ACM Workshop on Scientific Aspects of Cyber Terrorism 2002, PKC 2003, ICITS 2007, ISC 2013 and co-Program Chair of CANS 2005. He was an invited speaker at conferences and workshop in 5 continents. He has authored over 200 refereed papers. He has worked on cryptography, computer security, identification (entity authentication), information hiding, malware, network security, and other topics.