Journal of Computer Security

Integration of security and object-oriented techniques is critical for the successful deployment of distributed object systems. The CORBA Security services, first published in December of 1995 by the Object Management Group, is a detailed specification of how to handle security in object systems that conform to the Object Management Architecture. This article provides a rigorous definition of the authorization part of CORBA Security. Its semantics is given in terms of an access control matrix. The dependencies among the authorization elements are analyzed and possible interpretations for access control decision functions are given. The expressivity of the authorization model to define a wide range of policies, in particular mandatory access control, is discussed.

This paper describes an advanced authorization mechanism based on a logic formalism. The model supports both positive and negative authorizations. It also supports derivation rules by which an authorization can be granted on the basis of the presence or absence of other authorizations. Subjects, objects and authorization types are organized into hierarchies, supporting a more adequate representation of their semantics. From the authorizations explicitly specified, additional authorizations are automatically derived by the system, based on those hierarchies. The combination of all the above features results in a powerful yet flexible access control mechanism.

The logic formalism on which the system relies is an extension of Ordered Logic with ordered domains. This is an elegant yet powerful formalism whereby the basic concepts of the authorization model can be naturally formalized. Its semantics is based on the notion of stable model and assigns, to a given set of authorization rules, a multiplicity of (stable) models, each representing a possible way of assigning access authorizations. This form of non-determinism entails an innovative approach to enforce access control: when an access request is issued, the appropriate model (set of consistent access authorizations) is chosen, on the basis of the accesses currently under execution in the system.

Building on the work of Kocher (1996), Jaffe and Yun (1998), we discuss the notion of side-channel cryptanalysis: cryptanalysis using implementation data. We discuss the notion of side-channel attacks and the vulnerabilities they introduce, demonstrate side-channel attacks against three product ciphers – timing attack against IDEA, processor-flag attack against RC5, and Hamming weight attack against DES – and then generalize our research to other cryptosystems.

This paper addresses the problem of creating patterns that can be used to model the normal behavior of a given process. The models can be used for intrusion-detection purposes. First, we present a novel method to generate input data sets that enable us to observe the normal behavior of a process in a secure environment. Second, we propose various techniques to derive either fixed-length or variable-length patterns from the input data sets. We show the advantages and drawbacks of each technique, based on the results of the experiments we have run on our testbed.

This article presents an efficient public-key protocol for mutual authentication and key exchange designed for future mobile communications systems. The paper also demonstrates how a micropayment scheme can be integrated into the authentication protocol; this payment protocol allows for the provision of incontestable charging. The problem of establishing authenticated public keys through cross-certification is addressed.

Workflow Management Systems (WFMS) are being widely used today by organizations to coordinate the execution of various applications representing their day-to-day tasks. To ensure that these tasks are executed by authorized users or processes (subjects), and to make sure that authorized subjects gain access on the required objects only during the execution of the specific task, granting and revoking of privileges need to be synchronized with the progression of the workflow through proper authorization mechanisms. Recently, Atluri and Huang have proposed a workflow authorization model (WAM) that provides such synchronization. This paper, first extends WAM to support roles and authorization constraints such as separation of duties. Second, it develops methodologies to analyze the safety of workflow authorization model when authorization constraints are imposed. The analysis is carried out by modeling WAM as a suitable Petri net (PN) and by utilizing the well-established analysis techniques of PNs.