The idea is that nodes are trust-less, they do not know anything about the data.

An owner is authentified over an RSA handshake, so if the owner is not compromised, your request for updating a data will be rejected.

A malicous node though, must be both lucky (asked to share the data, so it can try to serve the malicious data) but also must have access to the link file so he can use the AES key to encrypt the bad data. This could happen if a malicious peron gets the hand on the link file, which sort of defeats the whole idea in the first place but it’s an attack vector for sure.

So back to the drawing board again.

The public RSA key of the owner is already in the link file, I think I can use it to authenticate the data (say the original user uses his private RSA to sign a hash of the data and adds it to the payload).

Very good feedback, I thought I had it all covered. It seems like I can make a secure fix but I’ll think a bit more about it first of course.