Cryptography in the Presence of Continous Side-Channel Attacks by Yevgeniy Vahlis, Columbia
Abstract: Recent trends in computing increasingly rely on delegating
computation both to centralized cloud computing environments, and to
mobile computers such as smart cards and mobile phones. This creates
new security risks and consequently new challenges for cryptography.
One such challenge stems from the fact that physical computational
devices leak information to the outside world through a variety of
side-channels-- physical characteristics of the device such as power
consumption, electromagnetic radiation, and timing. An attacker that
has physical possession of the device, or is within a short distance,
may use this information to learn about the internal state of the
device and about the computation that is currently being
performed. Such side-channel attacks have often been shown to break
the security of widely used cryptographic schemes without violating
any of the mathematical assumptions that underly the security of the
scheme.
In this talk I will present a general compiler that immunizes any
cryptographic functionality against long-term leakage through
side-channels. Our construction uses a single leak-free hardware
component and any fully homomorphic encryption scheme with
randomizable ciphertexts. The hardware component samples from a
publicly known distribution which does not depend on the functionality
that we wish to protect or its internal state. We prove the security
of our construction against an adversary that obtains leakage each
time the cryptographic functionality is used. The information leaked
can be any suitably length-bounded polynomial time computable function
of the active part of memory during computation. The total amount of
leakage that the construction can withstand is unbounded.
Our construction constitutes a first feasibility result, showing that
resilience against polynomial time leakage is possible without
performing any leak-free computation on the state of the protected
primitive. However, many directions remain open. I will describe
several such directions, and mention recent progress.
Joint work with Ali Juma.
Joanne Talbot Hanley
Last modified: Mon Aug 16 14:39:40 EDT 2010