Bilkent University
Department of Computer Engineering


Quantifying Computational Security against Brute-Force Attack


Dr. Ahmad Beirami
Duke University and MIT

Despite several proposals for alternatives, passwords remain the primary means of securing online accounts in the cloud. The mathematical framework for quantifying the computational security of passwords against brute-force attack by query is formed by the Massey-Arikan guesswork problem, which quantifies the number of queries required of an adversary to breach a system by guessing a secret string. In this talk, we provide finite-length approximations on the guesswork distribution, precise large deviations for guesswork, and precisely quantify the exponential growth of the average guesswork. We also show that hiding the statistics of a finite-memory string source only polynomially increases the average guesswork.

This talk is based on joint work with Robert Calderbank, Mark Christiansen, Ken Duffy, and Muriel Medard.

Bio: Ahmad Beirami received the B.Sc. degree in electrical engineering from Sharif University of Technology, Tehran, Iran, in 2007 and the M.Sc. and Ph.D. degrees in electrical and computer engineering from Georgia Institute of Technology, Atlanta, GA, USA, in 2011 and 2014, respectively. He is currently a Postdoctoral Associate jointly affiliated with Duke University and MIT working on problems spanning information theory, signal processing, statistics, and networks. His Ph.D. work received the 2013-2014 School of ECE Graduate Research Excellence Award, and the 2015 Sigma Xi Best Ph.D. Thesis Award from Georgia Institute of Technology.


DATE: 4 August, 2015, Tuesday @ 10:40