Towards mobile cryptography

Mobile code technology has become a driving force for recent advances in distributed systems. The concept of the mobility of executable code raises major security problems. In this paper, we deal with the protection of mobile code from possibly malicious hosts. We conceptualize the specific cryptographic problems posed by mobile code, and we are able to provide a solution for some of these problems. We present techniques to achieve “non-interactive evaluation with encrypted functions” in certain cases and give a complete solution for this problem in important instances. We further present a way in which an agent might securely perform a cryptographic primitive-digital signing-in an untrusted execution environment. Our results are based on the use of homomorphic encryption schemes and function composition techniques