Microsoft has announced that it has acquired Israel-based security company Secure Islands Technologies, confirming recent rumors that the deal was about to go ahead. While neither company has disclosed how much the acquisition is worth, sources familiar with the matter say that Microsoft paid $77.5 million for the purchase.

Microsoft plans to integrate Secure Islands' "advanced information protection solution" technology into its Azure Rights Management Service to help companies meet compliance and protection requirements of their cloud, on-premises and mobile data, Microsoft execs said.

The deal marks Microsoft's fifth purchase of an Israeli company, and two of these previous acquisitions were also security startups - cloud security vendors Adallom and Aorato (since rebranded as Advanced Threat Analytics).

Secure Islands was founded in 2006 and has raised $11.1 million to-date. Its technology is designed to protect data across virtually any type of file, and has been used by companies such as Vodafone, OSRAM, UBS, and Credit Suisse. Secure Islands has long been a close Microsoft partner and it will continue to offer its services to other customers after the deal is finalized.

"By joining Microsoft, we will be able to extend and expand our vision. Microsoft has been a long time partner and its leadership in enterprise IT, its resources and global reach will help us innovate and deliver new information protection capabilities to both our current and new customer base," Secure Islands CEO Aki Eldar said in a statement.

The deal is still awaiting regulatory approval but it's not expected to run into any problems. The acquisition represents Microsoft's continuing focus on improving the security of its Azure and Office 365 cloud-based services.