Enhanced Security for Mobile Agent Systems

Researchers agree that protecting a stand-alone autonomous mobile agent with software-only approaches remains difficult. In this thesis, we produce several results that enhance mobile agent security and provide generalized code protection. Generalized Black Box and White Box Program Protection. We provide a novel technique for hiding a candidate program's input/output relationships by using a data encryption padding technique. This method provides general program/circuit protection and relies on the semantic security strength found in common data encryption ciphers. For white box security, we semantically protect the white-box source code/gate structure information for relevant program classes defined by bounded input size. By using simple Boolean canonical circuit forms, we create an obfuscation technique that effectively hides all information regarding the source code or circuit gate structure. Leveraging our white-box results, we demonstrate how to embed an encryption key in programs that have small input size with measurable security. Analyzing Mobile Code Protection Schemes and Tamperproofing. We consider programmatic intent protection for mobile agents and pose a new model for obfuscated code security based on random programs. We also lay foundations for a new code protection methodology for mobile agents based on techniques used in the data encryption field. Specifically, we employ circuit encryption techniques that use combined sub-circuit permutation and substitution. Trust Framework for Mobile Agents and Application Security Models. We develop a novel framework to capture principles and trust relationships specific to the mobile agent paradigm. Application designers can also provide initial trust conditions to characterize the mobile execution environment; we seed a mobile interaction trust database with these conditions. We apply these models in context to our trust framework and show their relevance in designing secure mobile agent applications. Multiple-Agent Protection Schemes. Multiple agents provide greater capability for security in mobile contexts. We develop architecture for mobility utilizing hybrid secure multi-party computation models, trusted high-speed threshold servers, and multiple agents. We also develop a novel approach to deal with colluding malicious hosts in context to data state integrity attacks.