[Busec] BUsec this week: Chris Fletcher (Mon 10AM)

Sharon Goldberg goldbe at cs.bu.edu
Sun Dec 9 20:19:47 EST 2012

Hi all,

Tomorrow at 10AM, Chris Fletcher from MIT will be telling us about
implementations of fully homomorphic encryption.  Lunch will be
provided as usual. Abstract below.

See you then!

BUsec Calendar:  http://www.bu.edu/cs/busec/
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How to get to BU from MIT:  Try the CT2 bus or MIT's "Boston Daytime
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Techniques for performing secure computation on encrypted data
Speaker: Chris Fletcher, MIT
MCS137, Monday Dec 10, 10AM


Privacy of data is a huge problem in cloud computing, and more
generally in outsourcing computation.  From financial information to
medical records, sensitive data is stored and computed upon in the
cloud.  Computation requires the data to be exposed to the cloud
servers, which may be attacked by malicious applications, hypervisors,
operating systems or insiders.

In the ideal scenario, no one other than the user sees the private
data in decrypted form, as is achieved through the use of fully
homomorphic encryption (FHE) techniques.  The first part of the talk
will focus on (a) techniques to run general purpose programs under FHE
and (b) how some programs are naturally better suited for FHE than
others.  I will talk about the how ambiguity in program control flow
and data structures leads to large overheads for certain programs, in
addition to the crypto overheads already imposed by FHE (which impose
about a billion times slowdown).

Motivated by large FHE overheads, the second part of the talk
describes how to approximate FHE with a tamper-resistant processor
called Ascend.  Ascend performs program obfuscation in hardware: given
an untrusted program and private user data running within the Ascend
chip, the chip's external input/output and power pins give off a
signal that is independent of the private user data.  I will discuss
how strict periodic accesses to an Oblivious RAM obfuscate
input/output behavior and how strict periodic accesses to on-chip
circuits (e.g., on-chip caches) coupled with DPA-resistant techniques
obfuscate Ascend's power signature.  Surprisingly, Ascend incurs only
a ~5X performance overhead running SPEC benchmarks.  The trusted
computing base is only the Ascend chip: no software (the user
application, server operating system, etc) or anything outside the
Ascend processor (external RAM or communication channels) is trusted.

This is joint work with Marten van Dijk, Srini Devadas, Ling Ren and
Xiangyao Yu.

Sharon Goldberg
Computer Science, Boston University

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