The construction of secure mobile agents via evaluating encrypted functions

We propose a security approach for mobile agents, which protects mobile agents from malicious hosts. Our new approach prevents privacy attacks and integrity attacks to mobile agents from malicious hosts. It is an extension of mobile cryptography that removes many problems found in the original ideas of mobile cryptography while preserving most of the benefits. Although the original idea of mobile cryptography allowed direct computations without decryptions on encrypted mobile agents, it did not provide any practical ways of implementation due to the fact that no homomorphic encryption schemes are found for their approach. Our approach provides a practical idea for implementing mobile cryptography by suggesting a hybrid method that mixes a function composition technique and a homomorphic encryption scheme that we have found. Like the original mobile cryptography, our approach will encrypt both code and data including state information in a way that enables direct computation on encrypted data without decryption. We believe that our approach is a viable and practical means to address security problems such as integrity and privacy attacks to mobile agents.