Salil P. Vadhan

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Boosting is a general method for improving the accuracy of learning algorithms. We use boosting to construct improved {\em privacy-preserving synopses} of an input database. These are data structures that yield, for a given set $\Q$ of queries over an input database, reasonably accurate estimates of the responses to every query in~$\Q$, even when the number(More)
We efficiently combine unpredictability and verifiability by extending the Goldreich–Goldwasser–Micali construction of pseudorandom functions fs from a secret seed s, so that knowledge of s not only enables one to evaluate fs at any point x, but also to provide an NP-proof that the value fs(x) is indeed correct without compromising the unpredictability of(More)
Proofs of Retrievability (PoR), introduced by Juels and Kaliski [JK07], allow the client to store a file F on an untrusted server, and later run an efficient audit protocol in which the server proves that it (still) possesses the client’s data. Constructions of PoR schemes attempt to minimize the client and server storage, the communication complexity of an(More)
We give an improved explicit construction of highly unbalanced bipartite expander graphs with expansion arbitrarily close to the degree (which is polylogarithmic in the number of vertices). Both the degree and the number of right-hand vertices are polynomially close to optimal, whereas the previous constructions of Ta-Shma et al. [2007] required at least(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)
We continue the study of the trade-off between the length of PCP sand their query complexity, establishing the following main results(which refer to proofs of satisfiability of circuits of size <i>n</i>): 1 We present PCPs of length exp(&#213;(log log <i>n</i>)<sup>2</sup>)&#8226;<i>n</i> that can be verified by making <i>o</i>(log log<i>n</i>) Boolean(More)
We construct several new statistical zero-knowledge proofs with efficient provers, i.e. ones where the prover strategy runs in probabilistic polynomial time given an NP witness for the input string. Our first proof systems are for approximate versions of the Shortest Vector Problem (SVP) and Closest Vector Problem (CVP), where the witness is simply a short(More)
We consider the problem of constructing randomness extractors that are locally computable; that is, read only a small number of bits from their input. As recently shown by Lu locally computable extractors directly yield secure private-key cryptosystems in Maurer’s bounded-storage model. We suggest a general “sample-then-extract” approach to constructing(More)