Authentication with Partial Passwords and processing the shared secret with PHP

Recently at TBits.net, we wanted to even better secure the authentication to a web application that we provide to our customers. There are several options to extend authentication: security questions: https://en.wikipedia.org/wiki/Security_question another security token, eg. a YubiKey: https://en.wikipedia.org/wiki/Security_token partial passwords: https://en.wikipedia.org/wiki/Partial_Password and more…