[Cryptography] Explaining PK to grandma

[Ralf Senderek]

On Tue, 26 Nov 2013, Nico Williams wrote:

> Now in the virtual world you can duplicate anything. So you can have as many
> key-duplicates and box-duplicates as you would like. (implicit explaination of
> copying isn't a bad thing.)
>
> So it's a good idea to send everyone a duplicate of your close-key. That way
> they can lock something for only you to read.

Grandma wished it were that easy, but it isn't. With only public key 
crypto at hand, grandma gets some close key and has no means to check,
whether they have been sent by the one claiming to be the owner.
She is totally unprepared for the task to pick the trustworthy closing key 
out of the pile of keys she gets from everyone.

>
> And if someone comes to your home and wants to be absolutely sure it's you, they
> can ask you to use your openings key on one of your boxes! That way whoever's
> name is on the keys and boxes can be made sure of.

That's exactly what happens at a PGP key signing party, but grandma 
doesn't attend such stylish events.

      --Ralf