Ad hoc networks may not be suitable for “non ad hoc” applications due to resource, mobility, traffic pattern and incompatible wireless MAC protocols issues. We propose the Hierarchical Mobile Wireless Network for providing flexible and scalable network services to these applications. In such a system, mobile hosts are organized into hierarchical groups. Four basic operations that are used to set up and maintain the network structure are described. An efficient protocol for group membership management is discussed. The Segmented Membership-based Group Routing protocol is presented. In this routing protocol, only local message exchanging is required. Simulation-based experiments confirm the scalability of our design.

Digital Watermarking, in the traditional sense is the technique of embedding un-detectable (un-perceivable) hidden information into multimedia objects (i.e. images, audio, video, text) mainly to protect the data from unauthorized duplication and distribution by enabling provable ownership over the content.
  Recent research of the authors introduces the issue of digital watermarking for generic number sets. In the present paper we expand on this foundation and introduce a solution for relational database content security through watermarking. To the best of our knowledge there is no research on this issue. Our solution addresses a series of important attacks, such as data re-sorting, subset selection (up to 30% and above data loss tolerance), linear data changes. Finally we present dbwm.*, a proof-of-concept implementation of our algorithm and its application on real life data, namely in watermarking data from the outsourced Wal-Mart sales database of the years 1999-2000.

A good direction towards building secure systems that operate efficiently in large-scale environments (like the World Wide Web) is the deployment of Role Based Access Control Methods (RBAC). RBAC architectures do not deal with each user separately, but with discrete roles that users can acquire in the system. The goal of this paper is to present a classification algorithm that during its training phase, classifies roles of the users in clusters. The behavior of each user that enters the system holding a specific role is traced via audit trails and any misbehavior is detected and reported (classification phase). This algorithm will be incorporated in the Role Server architecture, currently under development, enhancing its ability to dynamically adjust the amount of trust of each user and update the corresponding role assignments.

This paper describes the design of a censorship-resistant distributed file sharing protocol which has been implemented on top of GNUnet, an anonymous, reputation-based network. We focus on the encoding layer of the GNUnet file-sharing protocol which supports efficient dissemination of encrypted data as well as queries over encrypted data. The main idea advocated in this paper is that simple cryptographic techniques are sufficient to engineer an efficient data encoding that can make it significantly harder to selectively censor information. Our encoding allows users to share files encrypted under descriptive keys which are the basis for querying the network for content. A key property of our encoding is that intermediaries can filter invalid encrypted replies without being able to decrypt the query or the reply. Files are stored in small chunks which are distributed and replicated automatically by the GNUnet infrastructure. Additionally, data files may be stored in plaintext or encrypted form or as a combination of both and encrypted on demand.

Auctions are communication-intensive enterprises.  Most scholarly examinations of auctions, however, have come from economics and sociology.  This paper applies a communication perspective to eBay, the largest online auction, and argues that eBay has maintained safety, order, and interest in its auctions by mimicking the oral style of the auctioneer and following the rules of in-person auctions, but in a virtual space.

This paper describes the design and implementation of a secure message broadcast system (SMBS). It is a secure, multi-party chat program that ensures privacy in communication and does not rely on shared secret keys. The system was built as a study of the feasibility of building effective communication tools using zero knowledge proofs. There is a general consensus in the computer security community that traditional password based authentication mechanisms are insuficient in today’s globally connected environment. Mechanisms such as one-time-passwords are a partial solution to the problem. The issue that these protocols don’t address is the lack of mutual authentication. The Kerberos family of systems addresses the issue of mutual authentication but relies heavily on the physical security of the server and safekeeping of the password database.

Security in computer systems is important to ensure reliable operation and protect the integrity of stored information.  Faults in the implementation can be exploited to breach security and penetrate an operating system.  These faults must be identified, detected, and corrected to ensure reliability and safe-guard against denial of service, unauthorized modification of data, or disclosure of information. We define a classification of security faults in the Unix operating system.  We state the criteria used to categorize the faults and present examples of the different fault types. We present the design and implementation details of a database to store vulnerability information collected from different sources.  The data is organized according to our fault categories.  the information in the database can be applied in static audit analysis of systems, intrusion detection, and fault detection.  We also identify and describe software testing methods that should be effective in detecting different faults in our classification scheme.