Samsung Knox on S4 gets approval from DoD
Knox is designed to make the S4's Android operating system more secure, adding strong encryption, secure VPN and work/personal data separation. It also supports policy-based device administration that IT departments can take advantage of.
Earlier this month, Samsung announced that the U.S. Department of Defense has given its approval for the use of Knox-enabled devices on their networks (the S4 is currently the only one on the market). Read more here: