Seals

[Adam Funk]

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!