Colloquium Speaker Mark Zhandry, Stanford University Monday, April 6, 12:30pm Computer Science 105 The Surprising Power of Modern Cryptography Modern cryptography is surprisingly powerful, yielding capabilities such as secure multiparty computation, computing on encrypted data, and hiding secrets in code. Currently, however, some of these advanced abilities are still too inefficient for practical use. The goals of my research are two-fold: (1) continue expanding the capabilities of cryptography and its applications, and (2) bring these advanced capabilities closer to practice. In this talk, I will focus on a particular contribution that addresses both of these objectives: establishing a shared secret key among a group of participants with only a single round of interaction. The first such protocols required a setup phase, where a central authority determines the parameters for the scheme; unfortunately, this authority can learn the shared group key and must therefore be trusted. I will discuss how to remove this setup phase using program obfuscation, though the scheme is very impractical due to the inefficiencies of current obfuscators. I will then describe a new technical tool called witness pseudorandom functions and show how to use this tool in place of obfuscation, resulting in a significantly more efficient protocol. Mark Zhandry is a Ph.D. candidate at Stanford University advised by Dan Boneh. He studies cryptography and computer science theory and is currently focusing on developing new cutting-edge cryptographic capabilities and improving the efficiency of these applications. He is visiting Microsoft Research New England and MIT for the 2014-15 academic year.