Abstract: How to protect mobile code against the tampering attempts by the malicious host is the key issue in the security of mobile agent and active networks. Recent works focus on how to utilize the resistant-hardware to protect mobile code against attack of remote malicious hosts. However, few researches are involved in designing pure-software approaches to protect mobile code against tampering. In this paper, the current pure-software solutions for the security of mobile agent are introduced and then a survey is given to the popular method: MCC （mobile code cryptography）, which can accomplish what is called blind computation of functions. The background and theory basis of MCC is introduced, and it is indicated that MCC is very different from traditional data cryptography. In addition, a novel concept, object oriented cryptography （OOC）, is proposed and the direction of MCC research and its potential application area are pointed out.