I wrote another article in 'Concerning Pharo': The code behind Google Authenticator Implementing Time-base One-Time Passwords in Pharo https://medium.com/concerning-pharo/the-code-behind-google-authenticator-9c5... I was curious how Google Authenticator, an iOS or Andriod mobile app used to implement two-factor authentication (2FA), really worked and how I could implement it myself. Since it is a lot of fun to experiment with and implement this kind of stuff in Pharo, I decided to give it a try. Note: fully documented source code with unit tests included. Sven -- Sven Van Caekenberghe Proudly supporting Pharo http://pharo.org http://association.pharo.org http://consortium.pharo.org