Browsing by Author "Katz, Jonathan"
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Item Automating Efficient RAM-Model Secure Computation(2014-03-13) Liu, Chang; Huang, Yan; Shi, Elaine; Katz, Jonathan; Hicks, MichaelRAM-model secure computation addresses the inherent limitations of circuit-model secure computation considered in almost all previous work. Here, we describe the first automated approach for RAM-model secure computation in the semi-honest model. We define an intermediate representation called SCVM and a corresponding type system suited for RAM-model secure computation. Leveraging compile-time optimizations, our approach achieves order-of-magnitude speedups compared to both circuit-model secure computation and the state-of-art RAM-model secure computation.Item KeyChains: A Decentralized Public-Key Infrastructure(2006-03-02T18:59:57Z) Morselli, Ruggero; Bhattacharjee, Bobby; Katz, Jonathan; Marsh, Michael A.A Certification Authority (CA) can be used to certify keys and build a public-key infrastructure (PKI) when all users trust the same CA. A decentralized PKI trades off absolute assurance on keys for independence from central control and improved scalability and robustness. The PGP ``web of trust'' model has been suggested as a decentralized certification system, and has been used with great success for secure email. Although the PGP web of trust model allows anyone to issue certificates which can be used to form certificate chains, the discovery and construction of certificate chains relies on centralized keyservers to store certificates and respond to queries. In this paper, we design and implement KeyChains, a peer-to-peer system which incorporates a novel lookup mechanism specifically tailored to the task of generating and retrieving certificate chains in completely unstructured networks. By layering our system on top of the web of trust model, we thus obtain the first PKI which is truly decentralized in all respects. Our analysis and simulations show that the resulting system is both efficient and secure.Item Trust-Preserving Set Operations(2003-09-25) Morselli, Ruggero; Bhattacharjee, Bobby; Katz, Jonathan; Keleher, PeteWe describe a method of performing trust-preserving set operations by untrusted parties. Our motivation for this is the problem of securely reusing content-based search results in peer-to-peer networks. We model search results and indexes as data sets. Such sets have value for answering a new query only if they are \emph{trusted}. In the absence of any system-wide security mechanism, a data set is trusted by a node $a$ only if it was generated by some node trusted by $a$. Our main contributions are a formal definition of the problem, and an efficient scheme that solves this problem by allowing untrusted peers to perform set operations on trusted data sets, and to produce unforgeable proofs of correctness. This is accomplished by requiring trusted nodes to sign appropriately-defined \emph{digests} of generated sets; each such digest consists of an RSA accumulator and a Bloom filter. The scheme is general, and can be applied to other applications as well. We give an analysis that demonstrates the low overhead of the scheme and we include experimental data which confirm the analysis. (UMIACS-TR-2003-68)