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SIA: Secure Information Aggregation in Sensor Networks
, 2003
"... Sensor networks promise viable solutions to many monitoring problems. However, the practical deployment of sensor networks faces many challenges imposed by realworld demands. Sensor nodes often have limited computation and communication resources and battery power. Moreover, in many applications se ..."
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Cited by 251 (13 self)
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Sensor networks promise viable solutions to many monitoring problems. However, the practical deployment of sensor networks faces many challenges imposed by realworld demands. Sensor nodes often have limited computation and communication resources and battery power. Moreover, in many applications sensors are deployed in open environments, and hence are vulnerable to physical attacks, potentially compromising the sensor's cryptographic keys. One of the basic and indispensable functionalities of sensor networks is the ability to answer queries over the data acquired by the sensors. The resource constraints and security issues make designing mechanisms for information aggregation in large sensor networks particularly challenging.
SIA: secure information aggregation in sensor networks
 Proc. of of ACM SenSys 2003
, 2003
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Assignment testers: Towards a combinatorial proof of the PCP theorem
 SIAM Journal on Computing
, 2004
"... In this work we look back into the proof of the PCP Theorem, with the goal of finding new proofs that are “more combinatorial ” and arguably simpler. For that we introduce the notion of an assignment tester, which is a strengthening of the standard PCP verifier, in the following sense. Given a state ..."
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Cited by 24 (3 self)
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In this work we look back into the proof of the PCP Theorem, with the goal of finding new proofs that are “more combinatorial ” and arguably simpler. For that we introduce the notion of an assignment tester, which is a strengthening of the standard PCP verifier, in the following sense. Given a statement and an alleged proof for it, while the PCP verifier checks correctness of the statement, the assignmenttester checks correctness of the statement and the proof. This notion enables composition that is truly modular, i.e., one can compose two assignmenttesters without any assumptions on how they are constructed. A related notion called PCPs of Proximity was independently introduced in [BenSasson et. al. STOC 04]. We provide a toolkit of (nontrivial) generic transformations on assignment testers. These transformations may be interesting in their own right, and allow us to present the following two main results: 1. The first is a new proof of the PCP Theorem. This proof relies on a rather weak assignment tester given as a “black box”. From this, we construct combinatorially the full PCP. An important component of this proof is a new combinatorial aggregation technique (i.e., a new transformation that allows the verifier to read fewer, though possibly longer, “pieces ” of the proof). An implementation of the blackbox tester can be obtained from the algebraic proof techniques that already appear in [BFLS91, FGL + 91]. Obtaining a combinatorial implementation of this tester would give a purely combinatorial proof for the PCP theorem, which we view as an interesting open problem. 2. Our second construction is a “standalone ” combinatorial construction showing NP ⊆ P CP [polylog, 1]. This implies, for example, that approximating maxSAT is quasiNPhard. This construction relies on a transformation that makes an assignment tester “oblivious”: so that the proof locations read are independent of the statement that is being proven. This eliminates, in a rather surprising manner, the need for aggregation in a crucial point in the proof. 1
Office Hours: TBA
, 2004
"... * The included papers are copyrights of the respective authors/universities and of ACM / IEEE respectively and are reproduced for academic purposes only. ..."
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* The included papers are copyrights of the respective authors/universities and of ACM / IEEE respectively and are reproduced for academic purposes only.
Verifying Server Computation
"... Abstract. In many scenarios, clients receive the results of computation which has been performed by a remote server. An example of such a setting is the thirdparty publishing model, in which a server answers arbitrary database queries posed by clients with data originally provided by a third party, ..."
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Abstract. In many scenarios, clients receive the results of computation which has been performed by a remote server. An example of such a setting is the thirdparty publishing model, in which a server answers arbitrary database queries posed by clients with data originally provided by a third party, who does not participate in the protocol. Previous work in this scenario has addressed range queries, but there has not previously existed a general solution for detecting cheating on the part of the server for arbitrary queries. We propose different two techniques for approximate proof construction to detect server misbehavior: spot checking and transformationbased checks. We develop proof constructions, using the spotchecking paradigm, for arbitrary database queries. We also offer an illustrative example of a use of the transformationbased check technique. 1