In the not too distant future, we could all be walking around with a smartphone app designed to track and follow the spread of Covid-19. This has sounded the privacy alarm bell, and Apple and Google have now further explained how their apps will work to try and calm things down. New documents posted online explain various aspects of the Bluetooth protocols, cryptography, and data storage that will be used, so everyone knows what they're getting into once they activate these apps. There are also frequently asked questions about the privacy implications. If you're familiar with this, Apple and Google are working together on phone software that will alert other people you've recently been physically close to if you contract Covid-19. The entire process will work anonymously, and so far is largely a work in progress, with no official release yet announced. We have a few more details today: Randomly generated keys and Bluetooth encryption will be used to make identifying people very, very difficult. If your phone rings to say you've been around someone who might have Covid-19, you won't know who it is, just that they've been in your general vicinity.