Following the announcement of the iPhone X with Face ID, sellers have started selling coloured masks on the Chinese equivalent of Amazon - Taobao.com - and on AliExpress, which they claim will stop others using the other's face to unlock their friend's or partner's phone whilst they are asleep.
However, the iPhone X can't be open using Face ID if the person's eyes are closed.
The new Face ID function is made up of "multiple innovative technologies" that give a "depth map" of the face.
Writing on their website about their new software, Apple shared: "Your face is now your password. Face ID is a secure new way to unlock, authenticate and pay. Face ID is enabled by the TrueDepth camera and is simple to set up. It projects and analyses more than 30,000 invisible dots to create a precise depth map of your face.
"What could be more natural than a touch? A look. That was the insight behind Face ID, a powerful and secure authentication system that's even more convenient than Touch ID. It makes unlocking and paying fast, easy and intuitive. The TrueDepth camera system is composed of multiple innovative technologies. Working together in real time, they use a detailed depth map of your face to recognise you in an instant.
"More than 30,000 invisible dots are projected onto your face to build your unique facial map. An infrared camera reads the dot pattern, captures an infrared image, then sends the data to the Secure Enclave in the A11 Bionic chip to confirm a match. Invisible infrared light helps identify your face even when it's dark."