Omer Reingold

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  • Omer Reingold
  • Electronic Colloquium on Computational Complexity
  • 2004
We present a <i>deterministic</i>, log-space algorithm that solves st-connectivity in undirected graphs. The previous bound on the space complexity of undirected st-connectivity was log<sup>4/3</sup> obtained by Armoni, Ta-Shma, Wigderson and Zhou [9]. As undirected st-connectivity is complete for the class of problems solvable by symmetric,(More)
We consider the question of protecting the privacy of customers buying digital goods. More specifically, our goal is to allow a buyer to purchase digital goods from a vendor without letting the vendor learn what, and to the extent possible also when and how much, it is buying. We propose solutions which allow the buyer, after making an initial deposit, to(More)
We present a <i>deterministic</i>, log-space algorithm that solves st-connectivity in undirected graphs. The previous bound on the space complexity of undirected st-connectivity was log<sup>4/3</sup>(&#7777;) obtained by Armoni, Ta-Shma, Wigderson and Zhou (JACM 2000). As undirected st-connectivity is complete for the class of problems solvable by(More)
We study the problem of privacy-preserving access to a database. Particularly, we consider the problem of privacy-preserving keyword search (KS), where records in the database are accessed according to their associated keywords and where we care for the privacy of both the client and the server. We provide efficient solutions for various settings of KS,(More)
Starting with the seminal paper of Impagliazzo and Rudich [18], there has been a large body of work showing that various cryptographic primitives cannot be reduced to each other via “black-box” reductions. The common interpretation of these results is that there are inherent limitations in using a primitive as a black box, and that these impossibility(More)
Luby and Rackoff [26] showed a method for constructing a pseudorandom permutation from a pseudorandom function. The method is based on composing four (or three for weakened security) so-called Feistel permutations, each of which requires the evaluation of a pseudorandom function. We reduce somewhat the complexity of the construction and simplify its proof(More)
We describe Just Fast Keying (JFK), a new key-exchange protocol, primarily designed for use in the IP security architecture. It is simple, efficient, and secure; we sketch a proof of the latter property. JFK also has a number of novel engineering parameters that permit a variety of tradeoffs, most notably the ability to balance the need for perfect forward(More)