3 research outputs found
A Simple Recursive Tree Oblivious RAM
Oblivious RAM (ORAM) has received increasing attention in the past few years. The goal of oblivious RAM is to enable a client, that can locally store only a small (preferably constant) amount of data, to store remotely N data items, and access them while hiding the identities of the items that are being accessed. Most of the earlier ORAM constructions were based on the hierarchical data structure of Goldreich and Ostrovsky. Shi et al. introduced a binary tree ORAM, which is simpler and more efficient than the classical hierarchical ORAM. Gentry et al. have improved the scheme. In this work, we improve these two constructions. Our scheme asymptotically outperforms all previous tree based ORAM schemes that have constant client memory, with an overhead of O(log^{2+eps}(N) * log^2(log(N))) per operation for a O(N) storage server. Although the best known asymptotic
result for ORAM is due to the hierarchical structure of Kushilevitz et al. (O(log^2(N)/log(log(N)))), tree based ORAM constructions are much simple
Peer-to-Peer Secure Multi-Party Numerical Computation Facing Malicious Adversaries
We propose an efficient framework for enabling secure multi-party numerical
computations in a Peer-to-Peer network. This problem arises in a range of
applications such as collaborative filtering, distributed computation of trust
and reputation, monitoring and other tasks, where the computing nodes is
expected to preserve the privacy of their inputs while performing a joint
computation of a certain function. Although there is a rich literature in the
field of distributed systems security concerning secure multi-party
computation, in practice it is hard to deploy those methods in very large scale
Peer-to-Peer networks. In this work, we try to bridge the gap between
theoretical algorithms in the security domain, and a practical Peer-to-Peer
deployment.
We consider two security models. The first is the semi-honest model where
peers correctly follow the protocol, but try to reveal private information. We
provide three possible schemes for secure multi-party numerical computation for
this model and identify a single light-weight scheme which outperforms the
others. Using extensive simulation results over real Internet topologies, we
demonstrate that our scheme is scalable to very large networks, with up to
millions of nodes. The second model we consider is the malicious peers model,
where peers can behave arbitrarily, deliberately trying to affect the results
of the computation as well as compromising the privacy of other peers. For this
model we provide a fourth scheme to defend the execution of the computation
against the malicious peers. The proposed scheme has a higher complexity
relative to the semi-honest model. Overall, we provide the Peer-to-Peer network
designer a set of tools to choose from, based on the desired level of security.Comment: Submitted to Peer-to-Peer Networking and Applications Journal (PPNA)
200
Analysis of the Linux Random Number Generator
Linux is the most popular open source project. The Linux random number generator is part of the kernel of all Linux distributions and is based on generating randomness from entropy of operating system events. The output of this generator is used for almost every security protocol, including TLS/SSL key generation, choosing TCP sequence numbers, and file system and email encryption. Although the generator is part of an open source project, its source code (about 2500 lines of code) is poorly documented, and patched with hundreds of code patches