Federated Learning Under Fire

Every time you type a message on your smartphone, your keyboard learns a little more about you. It notices your favourite words, your common misspellings, the names of people you text most often. For years, this intimate knowledge was hoovered up and shipped to distant servers, where tech giants analysed your linguistic fingerprints alongside billions of others. Then, around 2017, something changed. Google began training its Gboard keyboard using a technique called federated learning, promising