How to characterise the good old wax seal, in today’s “cyber”sec terminology ..?
- On envelopes and the like, it was a form of quantum encryption – any tampering would show, at the receiving end, compromittation of the encapsulating encryption; when including a tamper-proof or -indicative envelope / header&footer-encapsulation…)
- Non-repudiation of the sender, on parchment declarations.
- Proof of authority as in proof of authorisation, of course, too, via the authority attached to the seal bearer.
These three, as long as the key (seal ring) can’t be replayed (remade and applied) – weak key / key compromised.
Or stolen (replay, undue authority = privilege escalation).
And as long as the envelope couldn’t be invisibly compromised-and-restored, or read through the paper (wetting it up, then drying without damaging the contents) – weak encryption algo for the first item above.
Or the hash (second above) removed and attached to another parchment. Or the parchment text altered in a way that preserves non-repudiation (invisible, or in typical writing (hand-writing by default of other options like 8- or 9-dots matrix printers; we’re talking that long back).
This is getting out of hand; too much to add and elucidate. At least we don’t need the cumbersome physical seal of yesteryears and now have one tiny plug-in to secure all our communications forever, don’t we?
And, there were other protective measures as well:
[All hail the Duke of Lorraine at Nancy]