Instant messaging service Whatsapp has announced it will encrypt all its users' communications from Tuesday.
With end-to-end encryption, messages are scrambled as they leave the sender's device and can only be decrypted by the recipient's device.
It renders messages unreadable if they are intercepted, for example by criminals or law enforcement.
Whatsapp, which has a billion users worldwide, said file transfers and voice calls would be encrypted too.
The Facebook-owned company said protecting private communication was one of its "core beliefs".
Encryption was thrown under the spotlight after the FBI asked Apple to help it access data on an iPhone used by California gunman Syed Farook.
