40823641
The Integrity Challenge
Traditionally, system designers view integrity as Boolean: a system either has it or it doesn’t. In practice, of course, no real database enjoys complete integrity: invariably, a variety of factors conspire to make some information stale, missing, or just plain wrong. System design and analysis should recognize that real systems lack integrity, to some degree, most, if not all, of the time. Significant benefits flow from such recognition. Risk management techniques can identify the severity of different integrity loss scenarios, thereby focusing scarce resources on critical areas. A designer can deliberately sacrifice nonessential integrity under carefully controlled conditions to achieve other design objectives, such as performance, autonomy, availability, or security. Designers can achieve these objectives and still assure the preservation of essential aspects of integrity. Advanced applications can use explicit integrity markers on data to make integrity-dependent decisions. Powerful techniques can recognize and avoid impending integrity losses, or, failing that, recognize and contain damage and subsequently help restore integrity. The Internet revolution demands a new perspective on integrity, since the closed world assumption of traditional database design simply does not apply. Instead, data flows from a variety of new and evolving sources, some more trustworthy than others. Indeed, making sense of this torrent of information is one of the fundamental challenges of the present computing era. In this position paper, we outline some recent developments in integrity, and then outline some yet to be solved challenges.
31223197
Modeling Multilevel Entities Using Single Level Objects
An earlier paper by Jajodia and Kogan [5] introduced an approach for building multilevel secure object-oriented database systems based on a secure message filtering mechanism. Under this approach each object has a unique security level and, therefore, multilevel objects are not supported. In the present paper, we discuss an approach, based on composite objects, that allows multilevel entities to be represented in terms of single level objects. The main qualifying aspect of our approach is that the object interfaces can be provided to users as if multilevel objects were directly supported.
33341357
Information Release Control: A Learning-Based Architecture
Modern information system applications involve collaboration in the form of information flow through organization boundaries. Indeed, organizations have vast amounts of information that is shared with other organizations and even the general public for various purposes. In addition to the standard network-level protections, systems usually use some access control mechanisms to protect data. However, access control systems are not designed to deal with deliberate and accidental release of information, to which the user has the authority to access but is not supposed to be released. Moreover, effective access control assumes a perfect categorization of information, which is increasingly difficult in a complex information system. Information release control is viewed as complementary to access control, and aims at restricting the outgoing information flow at the boundary of information systems. This paper presents a general architectural view of a release control system, and discusses the integration in the proposed architecture of a module for learning release control constraints. Continuous learning is applied to adjust the release control constraints in order to reduce both mistakenly released and mistakenly restricted documents. The paper describes in detail the process of learning keyword-based release control constraints.
31726649
Scalable Group Rekeying for Secure Multicast: A Survey
Many group key management approaches have been recently proposed for providing scalable group rekeying to support secure communications for large and dynamic groups. We give an overview of these approaches and show the research trends. Finally, we discuss some new research directions on this subject.
21321848
Reasoning with advanced policy rules and its application
to access control
This paper presents a formal framework to represent and manage advanced policy rules, which incorporate the notions of provision and obligation. Provisions are those conditions that need to be satisfied or actions that must be performed by a user or an agent before a decision is rendered, while obligations are those conditions or actions that must be fulfilled by either the user or agent or by the system itself within a certain period of time after the decision. This paper proposes a specific formalism to express provisions and obligations within a policy and investigates a reasoning mechanism within this framework. A policy decision may be supported by more than one rule-based derivation, each associated with a potentially different set of provisions and obligations (called a global PO set). The reasoning mechanism can derive all the global PO sets for each specific policy decision and facilitates the selection of the best one based on numerical weights assigned to provisions and obligations as well as on semantic relationships among them. The formal results presented in the paper hold for many applications requiring the specification of policies, but this paper illustrates the use of the proposed policy framework in the security domain only.
28618164
Bootstrapping a data mining intrusion detection system
The application of data mining techniques in intrusion detection has received a lot of attention lately. Most of the approaches require of a training phase based on the availability of labelled data, where the labels indicate whether the points correspond to normal events or attacks. Unfortunately, this labelled data is not readily available in practice. In this paper we present a novel method based in intersecting segments of unlabelled data and using the intersection as the base data for unsupervised learning (clustering). The clustering algorithm, along with a method to find outliers with respect to the base clusters form the basis for separation of unlabelled data into groups of points that are normal (attack-free) and points that correspond to attacks. We show that the technique is very sucessful in separating points of the data sets of the DARPA, Lincoln Labs evaluation of 1999.
24298643
Translation of entity-relationship diagrams into relational structures
Abstract An entity-relationship diagram (ERD) is considered to have two conceptual domains: its upper and lower conceptual domains. The semantic properties intrinsic in the upper conceptual domain were studied recently by Lien. In this paper, we discuss the properties inherent in the lower conceptual domain. We show that the latter contains a significant portion of the semantic information of an ERD and helps determine its data representation power. We develop the notions of fundamental functional dependencies (FDs) which can be readily recognized for the lower conceptual domain of an ERD, and regular ERDs which are ERDs such that all the FDs present among their attributes can be derived from their fundamental FDs. Then we give conditions under which a large number of ERDs are equivalent to their underlying relational structures.
18022126
Construction of Universal Instances for Loop-Free Network Databases Using a Join-Like Operation
In this paper, we give a polynomial-time method to construct effectively the unique universal instance, using as few nulls as possible, from any loop-free network database, via a "minimal information" extension of natural join. Our results can be seen as concretely and quickly implementing the universal relation view for databases which are not pairwise consistent.
14430828
An Extension of "Representative Instances and &#947;-Acyclic Relational Schemes"
Let R be a γ-acyclic relational scheme, and let F be the set of functional dependencies (FD's) embodied in R. Given an existence constrained database r over R, it was shown in [1] that it is possible to connect tuples from different relations in r and construct a universal instance L, possibly containing null values δ, such that the total projection of L onto R yields exactly the set r. Moreover, conditions were given which guarantee that this L would satisfy the functional dependency with nulls (NFD) counterparts of FD's, in F. The purpose of this note is to generalize the latter result and show that under the same conditions, L actually satisfies NFD counterparts of FD's in the closure F+ of F.
120699
Enhancements to the Voting Algorithm
There are several consistency control algorithms for managing replicated files in the face of network partitioning due to site or communication link failures. In this paper, we consider the popular voting scheme along with three enhancements: voting with a primary site, dynamic voting, and dynamic voting with linearly ordered copiee. We develop a stochastic model which compares the file availabilities afforded by each of these schemes. We show that in this model dynamic voting with linearly ordered copies provides the greatest availability.
45839880
Universal and Representative Instances Using Unmarked Nulls
Representative instances are important since in addition to the universal relation view they permit updates in the individual relations; if these updates are locally valid, then they do not violate global consistency. In this paper, we first give conditions under which we can construct a universal instance I which uses only one type of nulls (unmarked nulls) and whose total projections onto the relation schemes yield exactly the database relations. Then, we give a necessary and sufficient condition under which this I is actually a representative instance. Our conditions are simple and easily maintained.