BEGIN:VCALENDAR VERSION:2.0 X-WR-CALNAME:Cryptography and Information Security Seminars 2007/2008 Events BEGIN:VEVENT DTSTART;TZID=US/Eastern:20080718T110000 DTEND;TZID=US/Eastern:20080718T123000 URL;VALUE=URI:http://www.csail.mit.edu/events/eventcalendar/calendar.php?show=event&id=1912 SUMMARY:Efficient Protocols in the Presence of Covert and Malicious Adversarie LOCATION:32-G449\, Patil/Kiva DESCRIPTION:Series: Cryptography and Information Security Seminars 2007/2008\nSpeaker: \, \nHost: Carmit Chazay\, Bar llan University\nContact: Be\, 3-6098\, imbe@mit.edu\nRefreshment Time: \nRelevant URL: \nIn this talk we present efficient secure protocols for a variety of tasks\, including oblivious transfer\, set intersection and pattern matching. Our protocols for securely computing the set intersection functionality are based on secure pseudorandom function evaluations\, in contrast to previous protocols that used secure polynomial evaluation. We also use secure pseudorandom function evaluation in order to achieve secure pattern matching. \nIn this case\, we utilize specific properties of the Naor-Reingold pseudorandom function in order to achieve high efficiency. Finally\, we show that using standard smartcards it is possible to construct truly practical secure protocols\, and demonstrate this on the problem of set intersection.\nWe consider a variety of adversary models and definitions of security in our results. Some of our protocols are secure in the presence of malicious adversaries with full simulation (via the ideal/real paradigm)\, and some provide only privacy. We also present protocols that are secure in the presence of covert adversaries. Loosely speaking\, this means that a malicious adversary can cheat\, but will then be caught with good probability. END:VEVENT BEGIN:VEVENT DTSTART;TZID=US/Eastern:20080801T103000 DTEND;TZID=US/Eastern:20080801T123000 URL;VALUE=URI:http://www.csail.mit.edu/events/eventcalendar/calendar.php?show=event&id=1920 SUMMARY:Chosen Ciphertext Security via Correlated Products LOCATION:32-G449\, Patil/Kiva DESCRIPTION:Series: Cryptography and Information Security Seminars 2007/2008\nSpeaker: Alon Rosen\, IDC Herzliya\nHost: Silvio Mical\, CSAIL\nContact: Be\, 3-6098\, imbe@mit.edu\nRefreshment Time: \nRelevant URL: \nIn this talk I will present a new notion of security\, called\none-wayness under correlated products. The question we are interested\nin is what are necessary and sufficient conditions for a function f\nand a distribution on inputs (x1\,...\,xk)\, so that the function\n(f(x1)\,...\,f(xk)) is one-way. The main motivation of this study is the\nconstruction of public-key encryption schemes that are secure against\nchosen-ciphertext attacks (CCA). We show that any collection of\ninjective trapdoor functions that is secure under very natural\ncorrelated products can be used to construct a CCA-secure public-key\nencryption scheme. The construction is simple\, black-box\, and admits a\ndirect proof of security.\n\nWe provide evidence that security under correlated products is\nachievable by demonstrating that any collection of lossy trapdoor\nfunctions\, a powerful primitive introduced by Peikert and Waters (STOC\n'08)\, yields a collection of injective trapdoor functions that is\nsecure under the above mentioned natural correlated products. Although\nwe eventually base security under correlated products on lossy\ntrapdoor functions\, we argue that the former notion is potentially\nweaker as a general assumption. Specifically\, there is no\nfully-black-box construction of loss trapdoor functions from trapdoor\nfunctions that are secure under correlated products.\n\nJoint work with Gil Segev.\n\n END:VEVENT END:VCALENDAR