Honestly, you have no idea how much it annoys me when someone uses the word “authentification”.  The word does not exist, people!*

It seems to be fairly widespread, I’m sad to say, amongst pieces of Linux and other open source software documentation, commonly within systems to authentiCATE users on websites.

Other alternative unwords in use are “authentify” and “authentificate”.

*Perhaps it does outside of the English language, but in that case write the entire document in that language, please!