Signature Schemes Secure against Hard-to-Invert Leakage: Angela Zottarel

Starts:
10:00 am on Wednesday, November 28, 2012
Ends:
11:00 am on Wednesday, November 28, 2012
Location:
MCS 137
Abstract: In the auxiliary input model an adversary is allowed to see a computationally hard-to-invert function of the secret key. The auxiliary input model weakens the bounded leakage assumption commonly made in leakage resilient cryptography as the hard-to-invert function may information-theoretically reveal the entire secret key. In this work, we propose the first constructions of digital signature schemes that are secure in the auxiliary input model. Our main contribution is a digital signature scheme that is secure against chosen message attacks when given an exponentially hard-to-invert function of the secret key. As a second contribution, we construct a signature scheme that achieves security for random messages assuming that the adversary is given a polynomial-time hard to invert function. Here, polynomial-hardness is required even when given the entire public-key – so called weak auxiliary input security. We show that such signature schemes readily give us auxiliary input secure identification schemes. Joint work with S. Faust, C. Hazay, J.B. Nielsen and P. S. Nordholt