Pete, Nov 20, 2017 : Hi everyone, Louis, our product manager, recently wrote a post about how the18:9 display, back fingerprint sensor and Face Unlock work together, but we also wanted to share a deeper dive into Face Unlock, which unlocks the phone in 0.4 seconds.Even though sales for the OnePlus 5T have just opened, we have already received a lot of questions about the technology. Therefore, we would like to offer a behind-the-scenes look into why we introduced Face Unlock and the technology behind it. On previous OnePlus devices, we placed our speedy, ceramic fingerprint sensor on the front to give users convenient and fast access to their phones. So, when we moved the fingerprint sensor to the back on the OnePlus 5T, we wanted to provide users a way to unlock the phone from the front of the device – with a focus on convenience and ease of access. Face Unlock is only designed as an additional option to open your device for the sake of convenience - Face Unlock is not enabled for Android Pay and other secure apps, such as banking apps. As we have seen from similar technologies, “100% secure” simply doesn’t exist, and that is why we still see the fingerprint sensor as a more secure method. We will continue to optimize the technology, but we also want to explain how the technology works. 1) Face Unlock makes sure it is you. It does so by analyzing, through the front camera, over 100 identifiers on your face such as the distance between your eyes or between your nose and upper lip. We have included numerous parameters, so that Face Unlock works in different lighting conditions as well as when you are wearing glasses. 2) Face Unlock makes sure is it you and that you are "alive". In simple words, the technology reduces the chance that someone will try to unlock your phone using a picture. There are multiple checks carried out such as analyzing the 3D aspect of the subject. To avoid putting out a checklist for people to use to work around Face Unlock, we would like to share one that we are currently working on that will be released in an upcoming OTA. To try to trick Face Unlock, someone might use a selfie on another phone and place this selfie in front of the OnePlus 5T in an effort to unlock it. Even though in real life you can argue that the risks of someone having physical access to your phone as well as a detailed enough selfie are low, we are always working to optimize Face Unlock. In an upcoming update, the phone will understand whether the subject is emitting light (a phone) versus reflecting (your actual face) by analyzing shadows and bright areas. Other current checks related to this particular scenario is to look for screen reflections, the presence of a square element (shape of the phone) and more. We are dedicated to constantly optimizing Face Unlock, much like we do with OxygenOS as a whole, and this is but one example. 3) To reduce the chance of someone trying to trick Face Unlock with multiple pictures, after five unsuccessful attempts, Face Unlock is deactivated, requiring you to use the fingerprint sensor or security code/pattern to unlock your phone. Also, for extra security, data sensitive apps such as banking apps can be added to our OxygenOS feature, App locker (settings>security & lock screen>App locker), which requires a fingerprint or security code/pattern to open the app, even if the phone was initially unlocked with Face Unlock. We hope our brief explanation of how Face Unlock works helps you to understand more about our latest feature. If you have any further queries, please do drop your question in the comments below.