&gt; The attacker uses the cracked 2005 stamping key to stamp the file and the cracked certificate to sign it.<p>OK, so you don&#x27;t actually understand how cryptographic timestamping works or the Bitcoin version. Please read up on it before commenting.<p>&gt; If you could certify a timestamp forever, in a non-expiring, uncrackable way, why wouldn&#x27;t you just use that for the whole file?<p>What you are timestamping <i>is</i> the whole file!