@simsa0 Implementing distributed authentication is in the current state of affairs overkill. Also, there is no way you could verify that the random thirdparty node you're using is actually trustworthy. And you'd require some weird supermagic that barely the non-web world hasn't figured out how to do user-friendly. This is a subject which requires years of research and hundreds of computer scientists and cryptographers to work together..
I know there are networks (#RedMatrix) who claim they do this in a way that they don't think is dangerous to the enduser's privacy or data integrity. I have not inspected their solution thoroughly, but I have strong doubts to the legitimacy of those claims.