I guess you mean previous.
Yes, looks like a fine architecture to me, for the little I know.
I’m not sure if there is a way to do that. Obviously, if ipfs does that, the timestamp has to come from the network, not from the node, since a modified node can change the timestamp before upload and sign that…
A guy already wondered if it could be done, but I don’t know the guts of the project to give a proper definitive answer to that. I had some thought, though: