MILENIO: A secure Java2-based mobile agent system with a comprehensive security Current mobile agent systems provide very simple security models. There is a lack of implementations allowing the administrator to manage system resources appropriately while offering comprehensive security to the server and agents against mutual or third party attacks. SAHARA is a security model for Java-based agent systems that takes advantage of the benefits of the Java2 SDK vl.2.1. SAHARA’s main goal is to create an integral security model that can be easily implemented by any system. This architecture offers the following features: specific assignment of privileges; agents’ authorities authentication using digital signatures; allowances management to limit resource consumption by each agent and authority, and a dynamic security policy that allows to modify the security permissions at runtime. Secure agent transmission and server authentication is achieved by using the SSL protocol Digital signatures are also used to protect agent’s code and to assign responsibility on the agent’s data. In order to verify the performance of the SAHARA security architecture we have created a mobile agent system called MILENIO with basic functionality, but with adequate security capabilities since it implements all SAHARA’s features. MILENIO also has also a user access restriction to avoid undesired users. We managed to create a secure mobile agent system with a graphical interface that can be used in any kind of mobile applications since it assures secure transactions for most of the applications. We also show the proper use of the Java2 security model in Java-based mobile agents systems.