A perception-based approach to content-based image representation and retrieval is proposed in this paper. We consider textured images and propose to model their textural content by a set of features having a perceptual meaning and their application to content-based image retrieval. We present a new method to estimate a set of perceptual textural features, namely […]
Color Extended Visual Cryptography Using Error Diffusion
Color visual cryptography (VC) encrypts a color secret message into color halftone image shares. Previous methods in the literature show good results for black and white or gray scale VC schemes, however, they are not sufficient to be applied directly to color shares due to different color structures. Some methods for color visual cryptography are […]
Rumor Riding: Anonymizing Unstructured Peer-to-Peer Systems
Although anonymizing Peer-to-Peer (P2P) systems often incurs extra traffic costs, many systems try to mask the identities of their users for privacy considerations. Existing anonymity approaches are mainly path-based: peers have to pre-construct an anonymous path before transmission. The overhead of maintaining and updating such paths is significantly high. We propose Rumor Riding (RR), a […]
A Privacy-Preserving Location Monitoring System for Wireless Sensor Networks
Monitoring personal locations with a potentially untrusted server poses privacy threats to the monitored individuals. To this end, we propose a privacy-preserving location monitoring system for wireless sensor networks. In our system, we design two in-network location anonymization algorithms, namely, resource and quality-aware algorithms, that aim to enable the system to provide high-quality location monitoring […]
Vulnerability Analysis in SOA-Based Business Processes
Business processes and services can more flexibly be combined when based upon standards. However, such flexible compositions practically always contain vulnerabilities, which imperil the security and dependability of processes. Vulnerability management tools require patterns to find or monitor vulnerabilities. Such patterns have to be derived from vulnerability types. Existing analysis methods such as attack trees […]
Improved Division by Invariant Integers
This paper considers the problem of dividing a two-word integer by a single-word integer, together with a few extensions and applications. Due to lack of efficient division instructions in current processors, the division is performed as a multiplication using a precomputed single-word approximation of the reciprocal of the divisor, followed by a couple of adjustment […]
Privacy-Preserving Updates to Anonymous and Confidential Databases
Suppose Alice owns a k-anonymous database and needs to determine whether her database, when inserted with a tuple owned by Bob, is still k-anonymous. Also,suppose that access to the database is strictly controlled, because for example data are used for certain experiments that need to be maintained confidential. Clearly,allowing Alice to directly read the contents […]
Nymble: Blocking Misbehaving Users in Anonymizing Networks
Anonymizing networks such as Tor allow users to access Internet services privately by using a series of routers to hide the client’s IP address from the server. The success of such networks, however, has been limited by users employing this anonymity for abusive purposes such as defacing popular Web sites. Web site administrators routinely rely […]
Robust Correlation of Encrypted Attack Traffic through Stepping Stones by Flow Watermarking
Network-based intruders seldom attack their victims directly from their own computer. Often, they stage their attacks through intermediate “stepping stones” in order to conceal their identity and origin. To identify the source of the attack behind the stepping stone(s), it is necessary to correlate the incoming and outgoing flows or connections of a stepping stone. […]
A Policy Enforcing Mechanism for Trusted Ad Hoc Networks
To ensure fair and secure communication in Mobile Ad hoc Networks (MANETs), the applications running in these networks must be regulated by proper communication policies. However, enforcing policies in MANETs is challenging because they lack the infrastructure and trusted entities encountered in traditional distributed systems. This paper presents the design and implementation of a policy […]