WhatsApp, currently one of the most popular messaging services in the world, wants to make it nearly impossible for anyone to snoop on its users. The company announced that it is taking privacy a step further by implementing end-to-end encryption for its 600 million users. This is considered to be one of the largest deployments of this type of encryption, which scrambles messages so that even the company doesn’t have access to its users’ unique cryptographic keys.

Users will not even notice a difference in their daily use of the popular app, but behind the scenes, WhatsApp is using an open-source software called TextSecure to scramble users’ messages.

TextSecure, which was created by a non-profit called Open Whisper Systems, will only work on Android devices, and it will only protect text messages. In the future, the company plans to expand its protection to include devices running iOS and encryption of group messages, picture messages, and video messages.

TextSecure scrambles messages using a cryptographic key that only the user can access. That key is never stored on the user’s device.

“The new encryption scheme means WhatsApp messages will now travel all the way to the recipients’ device before being decrypted, rather than merely being encrypted between the user’s device and WhatsApp’s server,” reports Wired.

WhatsApp also plans to add another security feature that will prevent man-in-the-middle attacks. The new encryption will make surveillance much harder for governments around the world.

WhatsApp has been working on end-to-end encryption for the past six months, but founder Jan Koum has had a life-long disdain for surveillance. He grew up in Soviet Ukraine in the 1980’s, and that led to his mission to protect privacy.

“I grew up in a society where everything you did was eavesdropped on, recorded, snitched on,” Koum said. “Nobody should have the right to eavesdrop, or you become a totalitarian state — the kind of state I escaped as a kid to come to this country where you have democracy and freedom of speech. Our goal is to protect it.”