[Busec] group meeting today - Rachel Lin - 1PM

Sharon Goldberg goldbe at cs.bu.edu
Mon Oct 3 07:55:07 EDT 2011


See you at 1PM in MCS137 for group meeting! Rachel Lin is presenting
and lunch will be provided.


---------- Forwarded message ----------
From: Huijia Rachel Lin <huijia at cs.cornell.edu>

Title: After-the-Fact Leakage in Public-Key Encryption

Abstract: What does it mean for an encryption scheme to be
leakage-resilient? Prior formulations require that the scheme remains
semantically secure even in the presence of leakage of the secret key,
but only considered leakage that occurs before the challenge
ciphertext is generated. Although seemingly necessary, this
restriction severely limits the usefulness of the resulting notion.

In this work we study after-the-fact leakage, namely leakage that the
adversary obtains after
seeing the challenge ciphertext. We seek a natural and realizable
notion of security, which is
usable in higher-level protocols and applications. To this end, we
formulate entropic leakage-
resilient PKE. This notion captures the intuition that as long as the
entropy of the encrypted
message is higher than the amount of leakage, the message still has
some (pseudo) entropy left.

We show that this notion is realized by the Naor-Segev constructions
(using hash proof systems). We demonstrate that entropic
leakage-resilience is useful by showing a simple construction that
uses it to get semantic security in the presence of after-the-fact
leakage, in a model of bounded memory leakage from a split state.

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