If the Clients sign the metadata, the server can't (current worstcase scenario) claim all files are deleted any more and not only content but also full metadata are key-protected. For the server the signature field would be an arbitrary field.
Only remaining issue is a server reset, where all signatures would be lost and the clients have to trust the server...
If the Clients sign the metadata, the server can't (current worstcase scenario) claim all files are deleted any more and not only content but also full metadata are key-protected. For the server the signature field would be an arbitrary field.
Only remaining issue is a server reset, where all signatures would be lost and the clients have to trust the server...