7357174
On the design and quantification of privacy preserving data mining algorithms
The increasing ability to track and collect large amounts of data with the use of current hardware technology has lead to an interest in the development of data mining algorithms which preserve user privacy. A recently proposed technique addresses the issue of privacy preservation by perturbing the data and reconstructing distributions at an aggregate level in order to perform the mining. This method is able to retain privacy while accessing the information implicit in the original attributes. The distribution reconstruction process naturally leads to some loss of information which is acceptable in many practical situations. This paper discusses an Expectation Maximization (EM) algorithm for distribution reconstruction which is more effective than the currently available method in terms of the level of information loss. Specifically, we prove that the EM algorithm converges to the maximum likelihood estimate of the original distribution based on the perturbed data. We show that when a large amount of data is available, the EM algorithm provides robust estimates of the original distribution. We propose metrics for quantification and measurement of privacy-preserving data mining algorithms. Thus, this paper provides the foundations for measurement of the effectiveness of privacy preserving data mining algorithms. Our privacy metrics illustrate some interesting results on the relative effectiveness of different perturbing distributions.
12715963
Multiple-antenna signal constellations for fading channels
In this correspondence, we show that the problem of designing efficient multiple-antenna signal constellations for fading channels can be related to the problem of finding packings with large minimum distance in the complex Grassmannian space. We describe a numerical optimization procedure for finding good packings in the complex Grassmannian space and report the best signal constellations found by this procedure. These constellations improve significantly upon previously known results.
6124477
A counterexample to a Voronoi region conjecture
Given a 2D-symmetric lattice /spl Lambda/, it was conjectured by Forney (1989) that the projection of the Voronoi region R(/spl Lambda/) onto two coordinates equals the Voronoi region of the constituent 2D-sublattice /spl Lambda//spl nu//sub 2/. We present a three-dimensional counterexample. >
11059176
Policy-based validation of SAN configuration
Historically, storage has been directly connected to servers for fast local access and easy configuration. In recent years, storage area networks (SANs) have defined an alternative storage paradigm that allows storage to be shared among servers using fast interconnects. One of the key challenges of SAN management is the large number of configuration problems that are encountered in a typical SAN deployment. These configuration problems can be addressed by SAN management software. However, hard-coding the SAN configuration rules into the management software is not a viable option since it is not possible to easily modify or replace old configuration rules and specify new policies and guidelines. In this paper, we propose a novel policy-based SAN configuration validation system that can be used to specify, store, and evaluate configuration policies for SANs. We also introduce five new operators for collection policies that are useful for evaluating a wide variety of practical SAN configuration policies found in practice. The policy-based SAN configuration checking approach proposed in this paper is discussed within the context of device interoperability constraints. However, this approach is extensible as it can also be used to enforce performance, reliability, and security-related configuration constraints.
13652126
Using certes to infer client response time at the web server
As businesses continue to grow their World Wide Web presence, it is becoming increasingly vital for them to have quantitative measures of the mean client perceived response times of their web services. We present Certes (CliEnt Response Time Estimated by the Server), an online server-based mechanism that allows web servers to estimate mean client perceived response time, as if measured at the client. Certes is based on a model of TCP that quantifies the effect that connection drops have on mean client perceived response time by using three simple server-side measurements: connection drop rate, connection accept rate and connection completion rate. The mechanism does not require modifications to HTTP servers or web pages, does not rely on probing or third party sampling, and does not require client-side modifications or scripting. Certes can be used to estimate response times for any web content, not just HTML. We have implemented Certes and compared its response time estimates with those obtained with detailed client instrumentation. Our results demonstrate that Certes provides accurate server-based estimates of mean client response times in HTTP 1.0/1.1 environments, even with rapidly changing workloads. Certes runs online in constant time with very low overhead. It can be used at websites and server farms to verify compliance with service level objectives.
9570200
Templates as Master Keys
We introduce two new attacks: the single-bit template attack and the template-enhanced DPA attack. The single-bit template attack can be used very effectively to classify even single bits in a single side channel sample with a high probability of correctness. The template-enhanced DPA attack, combines traditional DPA with single-bit template attacks to show that if an adversary has access to a test card with even a slightly biased RNG, then he/she can break protected cryptographic implementations on a target card even if they have perfect RNGs. In support of our claim, we report results from experiments on breaking two implementations of DES and AES protected by the masking countermeasure running on smartcards of different manufacturers. 
 
In light of these results, the threat of template attacks, generally viewed as intrinsically difficult to mount, needs to be reconsidered.
8921435
Distributed Pairwise Key Generation Using Shared Polynomials for Wireless Ad Hoc Networks
The infrastructure-less property of wireless ad hoc network makes the traditional central server based security management schemes unsuitable and requires the use of a distributed key management mechanism. In this paper, we propose a distributed pairwise key establishment scheme based on the concept of bivariate polynomials. In our method, any mobile node in an ad hoc network can securely communicate with other nodes just by knowing their corresponding IDs. The bivariate polynomials are shared in such a manner that the shares depend on the coefficient matrix of the polynomial, the requesting node’s ID and the ID of the nodes that respond to the request. We study the behavior of our scheme through simulations and show that our scheme compares well with other schemes and has a much better performance when averaged over the lifetime of the network.
7194636
Jigsaw-based secure data transfer over computer networks
In this paper, we present a novel encryption-less algorithm to enhance security in transmission of data in networks. The algorithm uses an intuitively simple idea of a "jigsaw puzzle" to break the transformed data into multiple parts where these parts form the pieces of the puzzle. Then these parts are packaged into packets and sent to the receiver. A secure and efficient mechanism is provided to convey the information that is necessary for obtaining the original data at the receiver-end from its parts in the packets, that is, for solving the "jigsaw puzzle". The algorithm is designed to provide information-theoretic (that is, unconditional) security by the use of a one-time pad like scheme so that no intermediate or unintended node can obtain the entire data. An authentication code is also used to ensure authenticity of every packet.
1271310
Policy ratification
It is not sufficient to merely check the syntax of new policies before they are deployed in a system; policies need to be analyzed for their interactions with each other and with their local environment. That is, policies need to go through a ratification process. We believe policy ratification becomes an essential part of system management as the number of policies in the system increases and as the system administration becomes more decentralized. In this paper, we focus on the basic tasks involved in policy ratification. To a large degree, these basic tasks can be performed independent of policy model and language and require little domain-specific knowledge. We present algorithms from constraint, linear, and logic programming disciplines to help perform ratification tasks. We provide an algorithm to efficiently assign priorities to the policies based on relative policy preferences indicated by policy administrators. Finally, with an example, we show how these algorithms have been integrated with our policy system to provide feedback to a policy administrator regarding potential interactions of policies with each other and with their deployment environment.
26743853
Design and Analysis of a Class of Highly Scalable Hierarchical Networks: PdBCube
Abstract A class of hierarchical networks called the dBCube, that provides cost-effective and high-performance communication in large multicomputer systems, has recently been introduced. Such a compound graph of a hypercube and a de Bruijn (dB) graph utilizes every node of the hypercube as a gateway for intercluster communication. This paper presents a partially connected dBCube subclass (PdBCube), wherein the use of fewer nodes as gateways makes the PdBCube highly scalable in terms of both the hypercube and the dB size. This enhancement in scalability can be achieved by two different approaches to assigning gateways. Performance degradation of the proposed PdBCube is illustrated in terms of diameter and average distance. Improvement in track efficiency and reduction in cost are observed to be directly related to a decrease in the number of remote links.
206391411
A Randomized Parallel Backtracking Algorithm
A technique for parallel backtracking using randomization is proposed. Its main advantage is that good speedups are possible with little or no interprocessor communication. The speedup obtainable is problem-dependent. In those cases where the problem size becomes very large, randomization is extremely successful achieving good speedups. The technique also ensures high reliability, flexibility, and fault tolerance. >