Mathematica--A System for Doing Mathematics by Computer.

A key element of any mobile code based distributed system are the security mechanisms available to protect (a) the host against potentially hostile actions of a code fragment under execution and (b) the mobile code against tampering attempts by the executing host. Many techniques for the first problem (a) have been developed. The second problem (b) seems to be much harder: It is the general belief that computation privacy for mobile code cannot be provided without tamper resistant hardware. Furthermore it is doubted that an agent can keep a secret (e.g., a secret key to generate digital signatures). There is an error in reasoning in the arguments supporting these beliefs which we are going to point out.

In this paper we describe software-only approaches for providing computation privacy for mobile code in the important case that the mobile code fragment computes an algebraic circuit (a polynomial). We further describe an approach how a mobile agent can digitally sign his output securely.

Protecting Mobile Agents Against Malicious Hosts

The intrusion detection system architectures commonly used in commercial and research systems have a number of problems that limit their configurability, scalability or efficiency. The most common shortcoming in the existing architectures is that they are built around a single monolithic entity that does most of the data collection and processing. In this paper, we review our architecture for a distributed intrusion detection system based on multiple independent entities working collectively. We call these entities autonomous agents. This approach solves some of the problems previously mentioned. We present the motivation and description of the approach, partial results obtained from an early prototype, a discussion of design and implementation issues, and directions for future work.

An architecture for intrusion detection using autonomous agents

Structure and interpretation of computer programs

Process migration is the act of transferring a process between two machines. It enables dynamic load distribution, fault resilience, eased system administration, and data access locality. Despite these goals and ongoing research efforts, migration has not achieved widespread use. With the increasing deployment of distributed systems in general, and distributed operating systems in particular, process migration is again receiving more attention in both research and product development. As high-performance facilities shift from supercomputers to networks of workstations, and with the ever-increasing role of the World Wide Web, we expect migration to play a more important role and eventually to be widely adopted.This survey reviews the field of process migration by summarizing the key concepts and giving an overview of the most important implementations. Design and implementation issues of process migration are analyzed in general, and then revisited for each of the case studies described: MOSIX, Sprite, Mach, and Load Sharing Facility. The benefits and drawbacks of process migration depend on the details of implementation and, therefore, this paper focuses on practical matters. This survey will help in understanding the potentials of process migration and why it has not caught on.

Process migration

Mobile agents are processes which can autonomously migrate to new hosts Despite its many practical benefits, mobile agent technology results in significant new security threats from malicious agents and hosts The primary added complication is that, as an agent traverses multiple hosts that are trusted to different degrees, its state can change in ways that adversely impact its functionality In this paper, we discuss achievable security goals for mobile agents, and we propose an architecture to achieve these goals The architecture models the trust relations between the principals of mobile agent systems A unique aspect of the architecture is a “state appraisal” mechanism that protects users and hosts from attacks via state modifications and that provides users with flexible control over the authority of their agents

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Security for Mobile Agents: Authentication and State Appraisal

Mobile agents are processes which can autonomously migrate to new hosts. Despite its many practical bene ts, mobile agent technology results in signi cant new security threats frommalicious agents and hosts. The primary added complication is that, as an agent traverses multiple hosts that are trusted to di erent degrees, its state can change in ways that adversely impact its functionality. In this paper, we investigate these new threats and develop a set of achievable security requirements for mobile agent systems.

/pdf/security-for-mobile-agents-issues-and-requirements-18q2s7mm7y.pdf

Security for Mobile Agents: Issues and Requirements

IMPS is an interactive mathematical proof system intended as a general-purpose tool for formulating and applying mathematics in a familiar fashion. The logic of IMPS is based on a version of simple type theory with partial functions and subtypes. Mathematical specification and inference are performed relative to axiomatic theories, which can be related to one another via inclusion and theory interpretation. IMPS provides relatively large primitive inference steps to facilitate human control of the deductive process and human comprehension of the resulting proofs. An initial theory library containing over a thousand repeatable proofs covers significant portions of logic, algebra, and analysis and provides some support for modeling applications in computer science.

IMPS: an interactive mathematical proof system

Little Theories

Church's simple theory of types is a system of higher-order logic in which functions are assumed to be total. We present in this paper a version of Church's system called PF in which functions may be partial. The semantics of PF, which is based on Henkin's general-models semantics, allows terms to be nondenoting but requires formulas to always denote a standard truth value. We prove that PF is complete with respect to its semantics. The reasoning mechanism in PF for partial functions corresponds closely to mathematical practice, and the formulation of PF adheres tightly to the framework of Church's system.

William M. Farmer

Papers

Security for Mobile Agents: Authentication and State Appraisal

Security for Mobile Agents: Issues and Requirements

IMPS: an interactive mathematical proof system

Little Theories

A Partial Functions Version of Church's Simple Theory of Types