Hi all,
We will have a visitor next week, Bhavana Kanukurthi, a collaborator of Leonid Reyzin from Boston University. Bhavana will give a talk on Wednesday, May 6, at 5 pm in IFW E44.
You are all very welcome to attend!
Stefan
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Title: Key Agreement from Close Secrets over Unsecured Channels Speaker: Bhavana Kanukurthi Affiliation: Boston University
Can you communicate securely with no public key infrastructure, strong secrets, and computational hardness assumptions? We consider information-theoretic key agreement between two parties sharing somewhat different versions of a secret w that has relatively little entropy. This setting arises, for example, when a trusted server stores the biometric of a user, and the user subsequently uses his fresh biometric reading to authenticate himself to the server. Such key agreement, also known as information reconciliation and privacy amplification over unsecured channels, was shown to be theoretically feasible by Renner and Wolf (Eurocrypt 2004), although no protocol that runs in polynomial time was described. We propose a protocol that is not only polynomial-time, but actually practical, requiring only a few seconds on consumer-grade computers.
Our protocol can be seen as an interactive version of robust fuzzy extractors (Dodis et al., Crypto 2006). While robust fuzzy extractors, due to their noninteractive nature, require w to have entropy at least half its length, we have no such constraint. In fact, unlike in prior solutions, in our solution the entropy loss is essentially unrelated to the length or the entropy of w, and depends only on the security parameter.
The paper appears in Eurocrypt 2009 and is available at http://eprint.iacr.org/2008/494. This is joint work with Leonid Reyzin. -------------------------------------------------------------------------------