Application Signing and Sandbox
This chapter discusses two critical security features in OS X: application signing and the App Sandbox. These technologies were both introduced with Mac OS 10.5 and provide facilities that improve the overall security of the platform. Incidentally, both technologies are also heavily leveraged by iOS, the underlying operating system on the iPhone, iPad, iPod Touch, and AppleTV.
Application signing is technology included in OS X that addresses the issue of application identity and integrity. Application signing provides protection to the operating system so that it can both uniquely identify an application and also determine whether the contents of the application have been modified. ...