Bad design and software defects often make source codes hard to understand and lead to maintenance difficulties. In order to detect and fix such defects, researchers have systematically investigated these issues and designed different effective algorithms to tackle the problems. However, most of these methods need source codes/models for defect detection and correction. Commercial companies, like banks, may not be willing to provide their source models due to data security. Therefore, it is a huge challenge to detect software detects by a consulting company as well as to keep source models confidential. This thesis analyze security issues in existing approaches related to defect detection and develop secure protocols to allow a software corporation and a consulting company to exchange data securely without revealing any private information, which make the approach practical in reality. The experimental results confirm the effectiveness of the proposed approach --Abstract, page iii
