FaceTime and “possibly” WhatsApp are the only applications that prevent governments from accessing the contents of communication, a cybersecurity expert said on Monday.

“Both offer end-to-end secure communications by default. FaceTime voice/video calls definitely aren’t backed up by default,” said Jonathan Mayer, a scholar at the Center for Internet and Society at the Stanford Law School. In comments to the Washington Examiner, he also said that WhatsApp text messages on Android are believed by many to be secure.