Sarah Tew/CNET

Samsung is now clear to start pitching its new flagship phone to the government.

The handset maker announced Friday that its Knox-enabled mobile devices have been approved by the Pentagon for government use. Samsung's Knox software offers high-level encryption, a VPN feature, and a way to separate personal data from work data. The software also enables IT administrators to manage a mobile device through specific policies.

For now, the Galaxy S4 is the only Samsung device equipped with Knox. But the company promises that other smartphones as well as tablets will receive the security software.

The thumb's up from the Pentagon means that the S4 and future Knox devices can be used by U.S. government and military departments that tap into the Department of Defense networks. Access to these networks requires high security standards, and the S4 is the first Android phone to meet the requirements, according to Samsung.

The new security clearance also opens up certain types of businesses as potential new customers for Samsung.

"We are very pleased to announce that the U.S. Department of Defense has approved Samsung Knox-enabled devices for use in DoD networks," Samsung Mobile President JK Shin said in a statement. "This approval enables other government agencies and regulated industries such as health care and financial services to adopt Samsung Galaxy smartphones and tablets. This is a significant milestone for Samsung as we work to grow our relationships within government and large corporate enterprises."

On Thursday, the Pentagon gave the same approval to BlackBerry devices with the BlackBerry 10 operating system, which translates into its Q10 and Z10 smartphones and Playbook tablets.

In the past, BlackBerry was the go-to vendor for government and big business due to the high-level security on its devices. But Apple and Android have begun carving out of a chunk of this lucrative market. Samsung in particular is aiming to muscle in on BlackBerry's territory with help from its Knox software.

Part of the Samsung for Enterprise (SAFE) initiative, Knox comes built into the operating system and addresses all major security holes in Android, according to the company. Knox's ability to keep personal and business data separate matches a similar feature in BB10 called BlackBerry Balance.

Up to now at least, BlackBerry hasn't appeared to be concerned about Samsung's efforts.

"Whatever any of our competitors announce, one thing won't change. The most secure mobile computing solution is a BlackBerry device running on a BlackBerry platform," David Smith, executive vice president of mobile computing for BlackBerry, said in February.

The government's nod to both Samsung and BlackBerrry still leaves Apple out in the cold.

The iPhone maker is also seeking approval from the Department of Defense for its mobile devices. Specifically, the DOD needs to certify the iOS 6 operating system as secure enough to be used by defense agencies and the military. However, that approval is expected within the next few weeks, The Wall Street Journal reported Wednesday.

Passing the government's security test doesn't automatically guarantee a sale. Approvals "do not directly result in product orders, but facilitate the process by eliminating the need for security reviews at the individual DOD organization level," a Defense Department spokesman told the Journal.

Samsung, BlackBerry, and potentially Apple will still need to fight over lucrative government contracts just as they do in the business world. But assuming Apple does win security approval, all three rivals will duke it out on an even playing field.