Facebook’s WhatsApp is adding encryption so messages cannot be deciphered when stored or traveling between devices, boosting efforts by technology companies to thwart snooping by hackers and government spies.

WhatsApp, which was acquired by Facebook for $22 billion this year, is working with startup Open Whisper Systems to enact the change, the companies said today. Open Whisper Systems said in a blog post that it has been working on encryption with the mobile-messaging service for the past six months.

A WhatsApp representative declined to comment beyond confirming the encryption.

Google and Apple, among other technology companies, have also recently expanded their use of encryption on mobile communications. The moves have drawn praise from privacy advocates and criticism from the Federal Bureau of Investigation and other law enforcement agencies for potentially hindering criminal investigations. U.S. attorney general Eric Holder and FBI director James Comey are among those who have said that they glean essential information from the contents of phones seized in criminal investigations.

The expanding use of encryption is part of a backlash among technology companies to leaked documents from former National Security Agency contractor Edward Snowden, which showed the U.S.’s widespread spying on digital communications. Doubts about the security of their technologies could cause U.S. companies to forgo as much as $35 billion in revenue through 2016, according to the Washington-based Information Technology & Innovation Foundation, a policy research group. (Bloomberg)