[Cryptography] Explaining PK to grandma

[Jerry Leichter]

On Nov 26, 2013, at 8:46 PM, John Kelsey wrote:

> All the user of the email system needs to know is that:
> 
> a.  Email to a given address can only be read by the owner of the address.
> 
> b.  Nobody can tell how much email you send or receive, or to/from whom.  
> 
> It's as silly to expect most users to understand the crypto underlying this as it is to expect them to understand the financial instruments and markets that make their credit card accounts possible....
All very true.  Several of you guys beat me to saying this.

*But*, there is one thing that may need, no so much "explanation" in the sense of conveying a deep understanding, as "training".  Somehow, a user of secure email has to know how to get a key for themselves; how to move that key to different machines; that they must *not* give that key to anyone else.  Conversely, they need to understand how to get some secure "thing" - I don't want to call it a "key" because it makes the term ambiguous and leads to people passing their private key to others - that you give to others so that they can reach you securely, and conversely that you have to get from them so that you can reach them securely.  Most of the actual work involved must be automated and invisible, but the decisions involved have to be made by the humans involved, and they need to understand the implications.

Given a carefully designed and implemented UI with appropriate stuff behind it, I think this could be done.  A beginning of an appropriate metaphor might be the keys to your house (perhaps your mailbox is better) for things that are, behind the scenes, private keys, vs. business cards with contact numbers and addresses, for things that are, behind the scenes, public keys.  The fact that mathematically they're "the same thing" is neither interesting nor relevant to most people, and certainly doesn't help them use the system.

There's no need to even mention signing keys - anything necessary can be handled silently along with encryption keys, and as far as users should be concerned, either a message is transfered "secure" - meaning encrypted *and* authenticated - or it isn't.
                                                        -- Jerry