GTACS

A Greater Tel-Aviv Area Seminar

Andrej Bogdanov@TAU on Limits of provable security for homomorphic encryption

We show that public-key bit encryption schemes which support weak homomorphic evaluation of parity or majority cannot be proved message indistinguishable beyond the intersection of AM and coAM via general (adaptive) reductions, and beyond statistical zero-knowledge via reductions of constant query complexity.

Towards these results, we show that any homomorphic evaluator for parity or majority over sufficiently many inputs can be converted into a rerandomization algorithm.

Based on joint work with Chin Ho Lee.

29/11/2012 - 14:00

Prabhanjan Ananth @ IDC on Non-transferable Proofs under Continual Memory Leakage

In a continual memory leakage attack, we consider a cryptosystem which updates its secret state at the end of each execution. An adversary attacking the system can learn arbitrary, but bounded, leakage on its secret state between any two successive updates. The public parameters of the system do not change during updates. Several basic cryptographic primitives, including public-key encryption and signatures, resilient to such attacks are now known.

20/06/2013 - 14:30

Yossi Oren@BIU on Cloning SRAM-Based Physically Uncloneable Functions

Physically Unclonable Functions (PUFs) are increasingly being proposed as central building blocks in cryptographic protocols and security architectures. The SRAM-based PUF is a proposed implementation of this primitive which reuses the existing memory of the underlying device and thus enjoys a very low implementation overhead.

13/06/2013 - 14:00

Adam O'Neill@TAU on Regularity of Lossy RSA on Subdomains and its Applications

We build on an approach of Kiltz et al. (CRYPTO ’10) and bring new techniques to bear on the study of how “lossiness” of the RSA trapdoor permutation under the $\Phi$-Hiding Assumption ($\Phi$A) can be used to understand the security of classical RSA-based cryptographic systems. In particular, we show that, under $\Phi$A, several questions or conjectures about the security of such systems can be reduced to bounds on the regularity (the distribution of the primitive $e$-th roots of unity mod $N$) of the ``lossy'' RSA map (where $e$ divides \Phi(N)).

25/06/2013 - 13:30

Alessandro Chiesa @TAU on Succinct Non-Interactive Arguments via Linear Interactive Proofs

Title: Succinct Non-Interactive Arguments via Linear Interactive Proofs
Speaker: Alessandro Chiesa (MIT)

Succinct non-interactive arguments (SNARGs) enable verifying NP statements with lower complexity than required for classical NP verification. Traditionally, the focus has been on minimizing the length of such arguments; nowadays researchers have focused also on minimizing verification time, by drawing motivation from the problem of delegating computation.

11/07/2013 - 14:00