[CSEE Talk] talk: cMix: Anonymization by High-Performance Scalable Mixing, 11:15am Fri 1/29

[Tim Finin]

                         Cyber Defense Lab
             University of Maryland, Baltimore County


      cMix: Anonymization by High-Performance Scalable Mixing

                           Farid Javani
                Cyber Defense Lab, CSEE Dept., UMBC

         11:15am-12:30pm Friday, 29 January 2015, ITE 231


cMix is a cryptographic protocol for mix networks that uses
pre-computations of a group-homomorphic encryption function to
avoid all real-time public-key operations by the senders, mix
nodes, and receivers. Like other mix network protocols, cMix can
enable an anonymity service that accepts inputs from senders and
delivers them to an output buffer, in a way that the outputs are
unlinkable to the inputs.  cMix's high-performance scalable
architecture, which results from its unique pre-computation
approach, makes it suitable for smartphone-to-smartphone use
while maintaining full anonymity sets independently per round.

Each sender establishes a shared key separately with each of the
mix nodes, which is used as a seed to a cryptographic
pseudorandom number generator to generate a sequence of message
keys.  Each sender encrypts its input to cMix with modular
multiplication by message keys.  cMix works by replacing the
message keys, which are not known in the pre-computation, in real
time with a precomputed random value.

Our presentation includes a detailed specification of cMix and
simulation-based security arguments. We also give performance
analysis, both modeled and measured, of our working prototype
currently running in the cloud.

cMix is the core technology underlying our larger PrivaTegrity
system that allows smart devices to carry out a variety of
applications anonymously (including sending and receiving chat
messages), with little extra bandwidth or battery usage.  This
talk focuses on cMix.

Joint work with David Chaum (Voting Systems Institute), Aniket
Kate (Purdue Univ.), Anna Krasnova (Radboud Univ.), Joeri de
Ruiter (Univ. of Birmingham), Alan T. Sherman (UMBC). See
http://bit.ly/CMIXp for details.


Favid Javani is a PhD student working with Dr. Sherman.  He
earned a MS from the Middle Eastern Technical University, Turkey,
with a thesis on lattice-based cryptography.

Host: Alan T. Sherman, sherman at umbc.edu