[Busec] busec this week: Michelle Mazurek (Friday 11am)

Sharon Goldberg goldbe at cs.bu.edu
Mon Feb 24 21:41:08 EST 2014

At 11am on Friday of this week, there is a security-related CS colloquium
on usable access control with Michelle Mazurek from CMU.  Next week, on
Wednesday at 9:30am, we have a BUsec seminar on anonymous credentials by
Foteini Baldimtsi from Brown.  We will have lunch in the BUsec lab starting
at *noon* on both days.

Note the unusual time of both talks and lunches!!!

See you there,


 BUsec Calendar:  http://www.bu.edu/cs/busec/
 BUsec Mailing list: http://cs-mailman.bu.edu/mailman/listinfo/busec
 How to get to BU from MIT: The CT2 bus or MIT's "Boston Daytime Shuttle"


CS Colloquium: Toward strong, usable access control for personal data
Michelle Mazurek. CMU.
Fri, February 28, 11am - 12pm
Hariri Institute, MCS180 @ 111 Cummington St Boston MA

Users create, store and access a lot of personal data, both on their
devices and in the cloud. Although this provides tremendous benefits, it
also creates risks to security and privacy, ranging from the inconvenient
(private photos posted around the office) to the serious (loss of a job;
withdrawal of college admission). Simply refusing to share personal data is
not feasible or desirable, but sharing indiscriminately is equally
problematic. Instead, users should be able to efficiently accomplish their
primary goals without unnecessarily compromising their privacy. In this
talk, I describe my work toward developing usable access-control mechanisms
for personal data. I review the results of three user studies that provided
insight into users' policy needs and preferences. I then discuss the design
and implementation of Penumbra, a distributed file system with built-in
access control designed to support those needs. Penumbra has two key
building blocks: semantic-tag-based policy specification and logic-based
policy enforcement. Our results show that Penumbra can enforce users'
preferred policies securely with low overhead.

Michelle Mazurek is a Ph.D. candidate in Electrical and Computer
Engineering at Carnegie Mellon University, co-advised by Lujo Bauer and
Greg Ganger. Her research interests span security, systems, and HCI, with
particular emphasis on designing systems from the ground up for usable
security. She has worked on projects related to usable access control,
distributed systems, and passwords.


Anonymous Credentials Light.
Foteini Baldimtsi. Brown.
Wed, March 5, 9:30am - 11:00am
MCS137 @ 111 Cummington St Boston MA

Abstract: Anonymous credential systems allow users to obtain and
demonstrate possession of digital credentials in order to authenticate
themselves in a privacy-preserving manner. When proving possession of a
credential a user reveals only the minimum amount of information
(attributes) required while the transactions to obtain and prove
credentials are unlinkable to each other.

In this talk we propose an efficient and provably secure (in the RO model)
anonymous credential scheme called "Anonymous Credentials Light"[BL'13a].
Our scheme is unlinkable under the decisional Diffie-Hellman assumption,
and unforgeable under the Discrete-Logarithm assumption for sequential
composition. In contrast to prior provably secure anonymous credential
schemes that were based on the RSA group or on groups with pairings our
construction only requires a few exponentiations in a prime-order group in
which the decisional Diffie-Hellman problem is hard and thus, is very
efficient even for lightweight devices. The only prior construction with
similar efficiency is the one due to Stefan Brands, however, as I will
briefly mention, we have shown that Brands scheme cannot be proven
unforgeable in the RO model under any intractability assumption [BL13b].
For our scheme, we define a new cryptographic building block, called "blind
signatures with attributes", and discuss how it can be used in combination
with a commitment scheme to directly get an anonymous credential system.
Finally, I will briefly explain how one can construct electronic cash with
attributes from our new building block and how it can be used for efficient
payments in public transportation.

[BL13a] "Anonymous Credentials Light", Foteini Baldimtsi and Anna
Lysyanskaya, ACM-CCS 2013.
[BL13b] "On the Security of One-Witness Blind Signature Schemes", Foteini
Baldimtsi and Anna Lysyanskaya, ASIACRYPT 2013.
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