<title>Mobile code security</title>

A Fast Data Protection Technique for Mobile Agents to Avoid Attacks in Malicious Hosts

Mobile agents are software entities that consist of code, data and state, and that can migrate autonomously from host to host executing their code. Security issues restrict the use of code mobility despite its benefits. The protection of mobile agents from the attacks of malicious hosts is considered by far the most difficult security problem to solve in mobile agent systems. Using a Trusted Third Party in the mobile agent system can aid to solve this problem. The Host Revocation Authority [2] is a TTP that controls which hosts acted maliciously in the past, and for this reason they have been revoked. Each agent sender consults the HoRA before sending an agent in order to remove from the agent’s itinerary all the malicious hosts. Accordingly, the revoked hosts will not receive mobile agents any more. This paper presents two new protocols that can be used to revoke malicious hosts.

Mobile agents' paradigm is increasingly being used on the global Internet, distributed systems and ambient intelligence environment. Indeed, they can provide many advantages to the development of dynamic applications. More recently, mobile agent paradigm is of the best prevalent alternatives bringing most of suitable characteristics of pervasive environments, where people are surrounded by intelligent interfaces merged in daily life objects. Yet, the success of dynamic environment based mobile agents and multi agent systems will depend on how secure it can be made. Certainly, their use poses many security threats, because they are exposed to different malicious hosts' and nodes attacks. The aim of this paper is to propose CAPMA, Clone agent to protect mobile agents. The approach is based on adaptability concept and a clone agent, which is a prototype of the mobile agent with no critical code and sensitive data. The idea minimizes damages on the mobile agent.

Mobile agent-based computing is an attractive model for distributed computation environment. A mobile agent has the unique ability to transfer from one host to another in the network. In multi-hop mobile agent system, the agent brings the produced offer from various remote hosts to its owner only after completing the visit to many remote hosts. Carrying the offer gathered from the preceding hosts to the succeeding hosts requires much security mechanisms to protect the offer from the malicious hosts, and also the owner has to wait for the arrival of offer until the mobile agent finishes its travel. To overcome this, an alternative model has been developed called matrix hop mobile agent (MHMA) system in which the mobile agent sends the offer collected from the host to the owner before it migrates to the next host. This research work proposes a new fault tolerant mechanism for MHMA to identify the malicious host and to protect the agent from various attacks, including colluded attack. In this proposed model, the owner calculates the expected waiting time for the arrival of offer from each remote host, using the transmission cost. If the offer does not reach the owner within the waiting time, the owner identifies the agent’s failure and retransmits the agent directly to the remote host. The implementation of this model enhances the performance of the MMHA in all kinds of e-service applications.

The security problem of mobile agent is important for applications using mobile agent technology. In this paper, we analyzed the security problems of mobile agent system exposed in opening environment and proposed a method to improve the authentication and credentials management in mobile agent environment. In our design, the trusted computing platform is used as the basic platform to running mobile agent systems, and the trusted platform module will used to help the authentication and credentials management. We also gave a model system for building trusted mobile agent system. In this system, the security of mobile agent is improved by using trusted computing platform which is linked with upper layer applications through the trusted software stack. Then, trusted services for mobile agent, including authentication, credential management and key storage, are supported.

Over the last couple of years we have been working on the development of mobile agents systems and their application to the areas of telecommunications and network management. This work has produced positive results: a competitive mobile agent platform was built, the run-time benefits of mobile agents were proved, and our industrial partners have developed practical applications that are being integrated into commercial products. However, despite the positive results, we feel that mobile agent technology is still not ready to enter the path of mainstream software development. In our perspective, one of the main reasons for this situation arises from the traditional approach to mobile agent technology. This approach, based on the familiar concept of the mobile-agent distributed platform as an extension of the operating system, focuses too much on the mobile agents and associated issues (mobility, agent lifecycle, security, coordination, etc.) and provides poor support for the development of applications where mobile agents are just one of several available technologies. Learning from past experience, we are now working on a new approach where the focus is brought back to the applications and mobile agents become just one the tools available to develop distributed systems. This provides a much lighter framework for application-based mobile agent systems. This paper presents the lessons learned from our previous project and discusses the new concept we are developing: application-centric mobile agent systems.

Mobile agent technology has been proposed for use on the Internet. The mobile agent is a software program that acts on behalf of a user or software. It has the following features: (1) it is autonomous; (2) it has one or more objectives; (3) it has a scope of competence; and (4) it may, or may not, collaborate and communicate with other software and users. 3 In order to perform its job, it is able to migrate from a source host to a target host on a network under its own control. 4 However, this may lead to a great deal of security threats and attacks. When a mobile agent moves between a series of hosts, it may happen to encounter either trust-worthy or malicious hosts. A mobile agent must be capable of authenticating legal hosts and other agents to avoid malicious attacks. Ideally, a mobile agent should be versatile, robust, and secure in changing environments. Therefore, the security issue when dealing with mobile agents becomes essential. So far, the research on mobile agent security has been focused on the following topics: 5

The flexibility offered by mobile agents is quite noticeable in distributed computing environments. However, the greater flexibility of the mobile agent paradigm compared to the client/server computing paradigm comes at an additional threats since agent systems are prone to failures originating from bad communication, security attacks, agent server crashes, system resources unavailability, network congestion, or even deadlock situations. In such events, mobile agents either get lost or damaged (partially or totally) during execution. In this paper, we propose parallel checkpointing approach based on the use of antecedence graphs for providing fault tolerance in mobile agent systems. During normal computation message transmission, the dependency information among mobile agents is recorded in the form of antecedence graphs by participating mobile agents of mobile agent group. When a checkpointing procedure begins, the initiator concurrently informs relevant mobile agents, which minimizes the identifying time. The proposed scheme utilizes the checkpointed information for fault tolerance which is stored in form of antecedence graphs. In case of failures, using checkpointed information, the antecedence graphs and message logs are regenerated for recovery and then normal operation continued. Moreover, compared with the existing schemes, our algorithm involves the minimum number of mobile agents during the identifying and checkpoiting procedure, which leads to the improvement of the system performance. In addition, the proposed algorithm is a domino-free checkpointing algorithm, which is especially desirable for mobile agent systems. Quantitative analysis and experimental simulation show that our algorithm outperforms other coordinated checkpointing schemes in terms of the identifying time and the number of blocked mobile agents and then can provide a better system performance. The main contribution of the proposed checkpointing scheme is the enhancement of graph-based approach in terms of considerable improvement by reducing message overhead, execution, and recovery times.

Security, especially attacks performed by hosts on visiting mobile agents (the malicious hosts problem), is a major obstacle that prevents mobile agent technology from being widely adopted. Being the running environment for mobile agents, the host has full control over them and could easily perform many kinds of attacks against them. This problem has not been fully solved yet. After the analysis of mobile agent security requirements, this paper first gives some design issues of a practical security model of the malicious hosts problem. Based on this, POM (Police Office Model), a mobile agent security model, is presented. By setting up special hosts called police offices within regions, POM can prevent most attacks performed by malicious hosts through the separation of the safety-critical parts of mobile agents from the malicious hosts.

Aiming at the security and trust management of mobile agent system in cloud computing environment, based on the simple public key infrastructure (SPKI) trust mechanism, a mobile agent system objective trust peer management model (MAOTM) is proposed to solve the problem of identity authentication, operation authorization and access control in the mobile agent system; On this basis, the Human Trust Mechanism (HTM) is used to study the subjective trust formation, trust propagation and trust evolution law, and the subjective trust dynamic management algorithm (MASTM) is proposed. Based on the interaction experience between the mobile agent and the execution host and the third-party recommendation information to collect the basic trust data, the public trust host selection algorithm is given. The isolated malicious host algorithm and the integrated trust degree calculation algorithm realize the function of selecting the trusted cluster and isolating the malicious host, so as to enhance the security interaction between the mobile agent and the host. The simulations of the proposed algorithms are verified and proved to be feasible and effective.

The key features of mobile agent systems are mobility, autonomy, and intelligence. On integrity protection within mobile agent technology, mobile agent integrity should be protected against attacks from malicious hosts and other agents. In this paper, we design flexible Mobile Agents (FMA). The traditional mobile agents consist of fixed code parts. But FMA consist of flexibly upgradeable agent code part for that new agent code modules can be added and redundant code modules can be deleted on the executing requirement. FMA prove to be more flexible in agent-based web systems compared to the traditional static-type mobile agent.KeywordsMobile AgentIntelligent AgentSecurityFlexibility

So far, agent research can be broadly categorized into two areas: intelligent agents and mobile agents. Intelligent agent research has grown from a background of AI, humancomputer interaction, and autonomous systems, while mobile agents research stems from the areas of distributed computing and networked systems. Intelligent agents research addresses intelligent control, planning, domain modeling, user modeling, perception, interagent cooperation, and adaptivity. Intelligent agents can take on many different roles, ranging from representing a human user’s interests to actively collaborating with users and each other. Intelligent agents are being designed to tackle nearly every tedious, non-creative activity that people perform (e.g., Web searches), as well as many more abstract functions (e.g., entertainment). Major issues in intelligent agents research include knowledge representation and communication, architectures for intelligent autonomy, mixed-initiative behavior, collaboration techniques, and learning. Mobile agents address physical communication, agent mobility, tracking and locating mobile agents, security and reliability of agents, etc. Mobile agents are suited for optimizing communication ‐ moving the action towards the source of data ‐ and thereby avoiding the need for huge data transfers. This is beneficial in data-intensive applications such as data mining. Mobility can also improve reliability in certain cases. In the field of electronic commerce, mobile agents naturally reflect the characteristics of buyer and the seller, effectively playing the roles of traveling salesman or broker. They can also be applied for easier software customization, software distribution, and to represent disconnected users. The main issues are in security, providing the infrastructure on the Web (naming, locating, controlling, and messaging) and improving survivability. The biggest challenge for all new agent technology is developing successful applications. For this minitrack, we selected two characteristics of agents that can span the diverging areas of intelligent and mobile agents: mobility and communication. The accepted papers reflect the research issues described in this summary. The minitrack is organized in three sessions. The first session explores the coordination of multiple intelligent agents using dramatically different communication schemes. Andersson and Ygge present an efficient market-based approach to managing very large scale groups of agents engaged in coordination via producer/ consumer transactions. Their CoTree algorithm allows largescale markets to operate efficiently with sparse communication, rapid updates as agent preferences change, and minimal data caching requirements on massively distributed systems. In contrast, Nelson, Penner, and Soken discuss the Interaction Society model of coordination, in which relatively small-scale groups of knowledge-intensive agents collaborate using complex communication about discrete tasking and information requirements. Their model for inter-agent communication and interactions with human users is being applied to build a multi-agent advising system for coordinating military Search and Rescue operations. Finally, Barbuceanu discusses the role of obligations and interdictions in the context of coarse-grain agent interactions. By explicitly capturing social obligations and the costs associated with violating those constraints, he shows how rational agents can achieve coordinated behavior without necessarily sharing goals. The second session addresses Java-based mobile agent systems. The paper by Covaci, Busse and Zhang, describes how a mobile agent system can be used for network management. Their framework is based on existing solutions such as TMN, and can be extended to SNMP.

Mobile agents can provide many benefits to the development of distributed applications. But the mobile agent system will face some security threat since it will run in an opening network environment. In this paper, we analyzed the security threats in mobile agent system and provided a method to build the trusted connect between entities in mobile agent environment. This method uses the trusted platform module in trusted computing platform as the trusted base. When a mobile agent wants to migrate to another platform, it should use a trusted connect between the source host and the goal host. The agent and agent platform can trust with each other. This method will be helpful to build a trusted computing environment for the mobile agent system.

Detecting and resolving deadlocks in mobile agent systems

Mobile agents are autonomous and dynamic entities that can migrate among various nodes in the network. Java`s Jini framework facilitates mobile agent system development, providing hey features for distributed network programming. However, due to the security weakness, Jinil.0 service has a fundamental limitation on developing mobile agent systems which support secure remote communications. In this paper, we describe a Jini2.0-based secure mobile agent system named SecureJMoblet. On the top of Jini2.0, the system provides basic functionalities of a mobile agent system such as creation, transfer and control. In addition, with the SeureJS developed for secure JavaSpace service, SecureJMoblet supports a secure object repository and a reliable communication among mobile agents.