Seals

[David Shaw]

On Tue, Nov 04, 2008 at 01:53:07PM +0000, Adam Funk wrote:
> On 2008-11-03, David Shaw wrote:
> 
> > Rather offtopic, but I read an interesting paper on seals a while back
> > (I'm afraid I don't recall where offhand).  Seals never really assured
> > confidentiality.  A person who wanted to open a letter would just make
> > a mold of the seal, melt it free, read the letter and then re-make the
> > seal using the mold.
> >
> > The countermeasure was to use multiple colors in the seal so that
> > melting it free would mix up the colors so the new seal wouldn't look
> > right.  The catch was that you'd have to send a drawing of how the
> > first seal looked using a different communications channel so the
> > recipient could compare...
> 
> Hey, that sounds like a key distribution problem!

Yep.  If you read about the history of crypto and message/information
security in general it's striking how things haven't really changed
all that much.  We do it faster/better/safer to be sure, but there are
a lot of fundamental concepts that have been around for hundreds or
even thousands of years.

David