What if you just take the map checksumming routine and apply it to all files loaded? That way, if skin checksums mismatched, it would be re-downloaded and overwritten, preventing the would-be hacker from ever using it.
I think Jit should just stop people with modified content from playing online completely. If it doesn't match, you get kicked. No need to waste our bandwidth, and no need to deal with people who try to play regardless.
What if the server downloads the checksum from a global server, then compares them to the client's?
I think the checking server would need the .map file to make sure everything is legit then.
No it wouldn't. It would just need the checksum of the correct .bsp file.