This tutorial paper explores the mechanics of protecting computer-stored information from unauthorized use or modification. It concentrates on those architectural structures--whether hardware or software--that are necessary to support information protection. The paper develops in three main sections. Section I describes desired functions, design principles, and examples of elementary protection and authentication mechanisms. Any reader familiar with computers should find the first section to be reasonably accessible. Section II requires some familiarity with descriptor-based computer architecture. It examines in depth the principles of modern protection architectures and the relation between capability systems and access control list systems, and ends with a brief analysis of protected subsystems and protected objects. The reader who is dismayed by either the prerequisites or the level of detail in the second section may wish to skip to Section III, which reviews the state of the art and current research projects and provides suggestions for further reading. Glossary The following glossary provides, for reference, brief definitions for several terms as used in this paper in the context of protecting information in computers. Access The ability to make use of information stored in a computer system. Used frequently as a verb, to the horror of grammarians. Access control list A list of principals that are authorized to have access to some object. Authenticate To verify the identity of a person (or other agent external to the protection system) making a request.

Current standard security practices do not provide substantial assurance that the end-to-end behavior of a computing system satisfies important security policies such as confidentiality. An end-to-end confidentiality policy might assert that secret input data cannot be inferred by an attacker through the attacker's observations of system output; this policy regulates information flow.

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this article we propose a standard for role-based access control (RBAC). Although RBAC models have received broad support as a generalized approach to access control, and are well recognized for their many advantages in performing large-scale authorization management, no single authoritative definition of RBAC exists today. This lack of a widely accepted model results in uncertainty and confusion about RBAC's utility and meaning. The standard proposed here seeks to resolve this situation by unifying ideas from a base of frequently referenced RBAC models, commercial products, and research prototypes. It is intended to serve as a foundation for product development, evaluation, and procurement specification. Although RBAC continues to evolve as users, researchers, and vendors gain experience with its application, we feel the features and components proposed in this standard represent a fundamental and stable set of mechanisms that may be enhanced by developers in further meeting the needs of their customers. As such, this document does not attempt to standardize RBAC features beyond those that have achieved acceptance in the commercial marketplace and research community, but instead focuses on defining a fundamental and stable set of RBAC components. This standard is organized into the RBAC Reference Model and the RBAC System and Administrative Functional Specification. The reference model defines the scope of features that comprise the standard and provides a consistent vocabulary in support of the specification. The RBAC System and Administrative Functional Specification defines functional requirements for administrative operations and queries for the creation, maintenance, and review of RBAC sets and relations, as well as for specifying system level functionality in sup...

As the World Wide Web has been used to build increasingly complex applications, developers have been constrained by the Web’s static document model. “Active ” content can add simple animations to a page, but it can also transform the Web into a “platform ” for writing and distributing programs. A variety of mobile code systems such as Java [Gosling et al.

Access control models have traditionally included mandatory access control...

This document was originally prepared off-line. This file is the result of scan, OCR, and manual touchup, starting

Abstract. In mobile code systems, programs or processes travel from host to host in order to accomplish their goals. Such systems violate some of the assumptions that underlie most existing computer security implementations. In order to make these new systems secure, we will have to deal with a number of issues that previous systems have been able to ignore or sidestep. This paper surveys the assumptions that mobile code systems violate (including the identification of programs with persons, and other assumptions that follow from that), the new security issues that arise, and some of the ways that these issues will be addressed. 1

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The file protection mechanism provided in UNIX is insufficient for current computing environments. While the UNIX file protection system attempts to protect users from attacks by other users, it does not directly address the agents of destruction--- executing processes. As computing environments become more interconnected and interdependent, there is increasing pressure and opportunity for users to acquire and test non--secure, and possibly malicious, software. We introduce TRON, a process--level discretionary access control system for UNIX. TRON allows users to specify capabilities for a process' access to individual files, directories, and directory trees. These capabilities are enforced by system call wrappers compiled into the operating system kernel. No privileged system calls, special files, system administrator intervention, or changes to the file system are required. Existing UNIX programs can be run without recompilation under TRON--enhanced UNIX. Thus, TRON improves UNIX secu...