As of October 17th, the Kagan Kalender is only reachable via https. This means that all communication between your web browser and the web server is encrypted. For example, if you submit your password to login, this password will be encrypted before it’s sent to the web server. As such a hacker who is eavesdropping the connection between your web browser and the web server is not able to retrieve your password.
The consequence of the change to https however is that the Kagan Kalender website will only work again if you clear your web browser cache.