In Samsung GALAXY S4, Samsung KNOX provides container management and policies compliant with the U.S. Department of Defense (DOD) mobile OS security requirements guide (SRG). Offering SRG-compliant, robust security, Samsung KNOX protects your mobile device at the operating system Knox is Samsung's way to get past IT's legitimate concerns over Android's generally weak security and join Apple's iOS and BlackBerry in the golden circle of trustworthy mobile devices... hope it help you :-)
