[Busec] BUsec this week: Rita Vald (Tues 11AM)

Sharon Goldberg goldbe at cs.bu.edu
Sun May 6 14:10:18 EDT 2012


All,

Our seminars continue next week with our own Rita Vald presenting new
work on Universal Composability.  We meet in MCS137 on Tuesday 11AM as
usual, with lunch.

See you there!
Sharon

Title:Universally Composable Security With Local Adversaries
Speaker: Rita Vald, BU and TAU
MCS137

The traditional approach to formalizing ideal-model based definitions
of security for multi-party protocols models adversaries (both real
and ideal) as centralized entities that control all parties that
deviate from the protocol. While this centralized-adversary modeling
suffices for capturing basic security properties such as secrecy of
local inputs and correctness of outputs against coordinated attacks,
it turns out to be inadequate for capturing security properties that
involve restricting the sharing of information between separate
adversarial entities. Indeed, to capture collusion-freeness and and
game-theoretic solution concepts, Alwen et.al. [Crypto, 2012] propose
a new ideal-model based definitional framework that involves a
de-centralized adversary.

We propose an alternative framework to that of Alwen et. al. We then
observe that our framework allows capturing not only
collusion-freeness and game-theoretic solution concepts, but also
several other properties that involve the restriction of information
flow among adversarial entities. These include some natural flavors of
anonymity, deniability, timing separation, and information
confinement. We also demonstrate the inability of existing formalisms
to capture these properties.

We then prove strong composition properties for the proposed
framework, and use these properties to demonstrate the security,
within the new framework, of two very different protocols for securely
evaluating any function of the parties’ inputs.

Joint work with Ran Canetti.



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