To write a security software,a project team should working as follow:

1.Security Training

2.Defining Security Requirements

3.Secure Design

4.Secure Coding

5.Secure Source Code Handling: including tight change management and tracking and confidentiality protection of code such that only authorized persons are permitted to view or modify its contents in order to prevent malicious insiders

6.Security Testing

7.Security Documentation:to help customers understand how to optimally configure security controls, and how configuration options

8.Security Readiness

9.Security Response

10.Integrity Verification

11.Security Research

12.Security Evangelism