Weizmann Logo
Electronic Colloquium on Computational Complexity

Under the auspices of the Computational Complexity Foundation (CCF)

Login | Register | Classic Style

All reports by Author Rafail Ostrovsky:

TR15-056 | 3rd April 2015
Sanjam Garg, Steve Lu, Rafail Ostrovsky

Black-Box Garbled RAM

Garbled RAM, introduced by Lu and Ostrovsky, enables the task of garbling a RAM (Random Access Machine) program directly, there by avoiding the inefficient process of first converting it into a circuit. Garbled RAM can be seen as a RAM analogue of Yao's garbled circuit construction, except that known realizations ... more >>>

TR13-143 | 19th October 2013
Yuval Ishai, Eyal Kushilevitz, Xin Li, Rafail Ostrovsky, Manoj Prabhakaran, Amit Sahai, David Zuckerman

Robust Pseudorandom Generators

Revisions: 1

Let $G:\{0,1\}^n\to\{0,1\}^m$ be a pseudorandom generator. We say that a circuit implementation of $G$ is $(k,q)$-robust if for every set $S$ of at most $k$ wires anywhere in the circuit, there is a set $T$ of at most $q|S|$ outputs, such that conditioned on the values of $S$ and $T$ ... more >>>

TR12-164 | 17th November 2012
Rafail Ostrovsky, Ivan Visconti

Simultaneous Resettability from Collision Resistance

In FOCS 2001, Barak, Goldreich, Goldwasser and Lindell conjectured that the existence of ZAPs, introduced by Dwork and Naor in FOCS 2000, could lead to the design of a zero-knowledge proof system that is secure against both resetting provers and resetting verifiers. Their conjecture has been proven true by Deng, ... more >>>

TR12-104 | 8th August 2012
Matthew Franklin, Ran Gelles, Rafail Ostrovsky, Leonard Schulman

Optimal Coding for Streaming Authentication and Interactive Communication

Revisions: 1

Error correction and message authentication are well studied in the literature, and various efficient solutions have been suggested and analyzed. This is however not the case for data streams in which the message is very long, possibly infinite, and not known in advance to the sender. Trivial solutions for error-correcting ... more >>>

TR11-118 | 6th September 2011
Brett Hemenway, Rafail Ostrovsky, Martin Strauss, Mary Wootters

Public Key Locally Decodable Codes with Short Keys

This work considers locally decodable codes in the computationally bounded channel model. The computationally bounded channel model, introduced by Lipton in 1994, views the channel as an adversary which is restricted to polynomial-time computation. Assuming the existence of IND-CPA secure public-key encryption, we present a construction of public-key locally decodable ... more >>>

TR10-127 | 9th August 2010
Brett Hemenway, Rafail Ostrovsky

Building Injective Trapdoor Functions From Oblivious Transfer

Revisions: 1

Injective one-way trapdoor functions are one of the most fundamental cryptographic primitives. In this work we give a novel construction of injective trapdoor functions based on oblivious transfer for long strings.

Our main result is to show that any 2-message statistically sender-private semi-honest oblivious transfer (OT) for ... more >>>

TR09-127 | 25th November 2009
Brett Hemenway, Rafail Ostrovsky

Lossy Trapdoor Functions from Smooth Homomorphic Hash Proof Systems

Revisions: 2

In STOC '08, Peikert and Waters introduced a powerful new primitive called Lossy Trapdoor Functions (LTDFs). Since their introduction, lossy trapdoor functions have found many uses in cryptography. In the work of Peikert and Waters, lossy trapdoor functions were used to give an efficient construction of a chosen-ciphertext secure ... more >>>

TR09-108 | 31st October 2009
Chongwon Cho, Chen-Kuei Lee, Rafail Ostrovsky

Equivalence of Uniform Key Agreement and Composition Insecurity

Revisions: 1

It is well known that proving the security of a key agreement protocol (even in a special case where the protocol transcript looks random to an outside observer) is at least as difficult as proving $P \not = NP$. Another (seemingly unrelated) statement in cryptography is the existence of two ... more >>>

TR07-022 | 20th February 2007
Rafail Ostrovsky, William Skeith

Algebraic Lower Bounds for Computing on Encrypted Data

In cryptography, there has been tremendous success in building
primitives out of homomorphic semantically-secure encryption
schemes, using homomorphic properties in a black-box way. A few
notable examples of such primitives include items like private
information retrieval schemes and collision-resistant hash functions. In this paper, we illustrate a general
methodology for ... more >>>

TR07-021 | 5th March 2007
Brett Hemenway, Rafail Ostrovsky

Public Key Encryption Which is Simultaneously a Locally-Decodable Error-Correcting Code

Revisions: 3

In this paper, we introduce the notion of a Public-Key Encryption (PKE) Scheme that is also a Locally-Decodable Error-Correcting Code.
In particular, our construction simultaneously satisfies all of the following properties:
Our Public-Key Encryption is semantically secure under a certain number-theoretic hardness assumption
... more >>>

TR06-110 | 15th August 2006
Nishanth Chandran, Ryan Moriarty, Rafail Ostrovsky, Omkant Pandey, Amit Sahai

Improved Algorithms for Optimal Embeddings

In the last decade, the notion of metric embeddings with
small distortion received wide attention in the literature, with
applications in combinatorial optimization, discrete mathematics, functional
analysis and bio-informatics. The notion of embedding is, given two metric
spaces on the same number of points, to find a bijection that minimizes
more >>>

TR06-095 | 25th July 2006
Rafail Ostrovsky, Giuseppe Persiano, Ivan Visconti

Concurrent Non-Malleable Witness Indistinguishability and its Applications

Revisions: 1

One of the central questions in Cryptography today is proving security of the protocols ``on the Internet'', i.e., in a concurrent setting where there are multiple interactions between players, and where the adversary can play so called ``man-in-the-middle'' attacks, forwarding and modifying messages between two or more unsuspecting players. Indeed, ... more >>>

TR05-097 | 31st August 2005
Jens Groth, Rafail Ostrovsky, Amit Sahai

Perfect Non-Interactive Zero Knowledge for NP

Non-interactive zero-knowledge (NIZK) systems are
fundamental cryptographic primitives used in many constructions,
including CCA2-secure cryptosystems, digital signatures, and various
cryptographic protocols. What makes them especially attractive, is
that they work equally well in a concurrent setting, which is
notoriously hard for interactive zero-knowledge protocols. However,
while for interactive zero-knowledge we ... more >>>

TR94-007 | 12th December 1994
Oded Goldreich, Rafail Ostrovsky, Erez Petrank

Computational Complexity and Knowledge Complexity

We study the computational complexity of languages which have
interactive proofs of logarithmic knowledge complexity. We show that
all such languages can be recognized in ${\cal BPP}^{\cal NP}$. Prior
to this work, for languages with greater-than-zero knowledge
complexity (and specifically, even for knowledge complexity 1) only
trivial computational complexity bounds ... more >>>

ISSN 1433-8092 | Imprint