

Why Johnny Can't Encrypt (1999 USENIX paper) - henning
http://www.usenix.org/publications/library/proceedings/sec99/full_papers/whitten/whitten_html/index.html

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Tycho
All the stuff about private and public keys was a bit of a haze to me until I
invested a few hours in reading up on cryptography and specifically the
Diffie-Hellman Key Exchange. I postulate that the problem here is (was?) one
of terminology and/or education, rather than interface design.

Incidentally I thought the article was going to be about why amateurs
can't/shouldn't write encryption algorithms (having inquired about this myself
on Stack Overflow and been royally shouted down).

~~~
ganjianwei
I agree with the terminology being a problem. Regarding private key public key
encryption, I think the public key should be called the "lock" since people
use it to lock data they want to send you, while the private key should be
called the "key" because you use it to "unlock"(decrypt) the data.

But this messes up when you use the same terms for other uses of
public/private keys such as authentication. Still, the terms could provide a
better mental model for people new to it to understand.

~~~
dalore
That breaks down when you use your private key [aka the "key"] to encrypt/sign
something when you send it out. It proves it came from you because your public
key [aka the "lock"] can decrypt it.

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thejo
This paper is very popular / influential in the area of usable security. It's
interesting to note that though it's possible to securely exchange e-mail,
most people don't. I took a course offered by Prof. Tygar (co-author of the
paper) last year and we evaluated how easy it is to send encrypted mail using
Thunderbird+Enigmail+GnuPG. While the usability of the software has improved
in the 10 years since the paper was written, it is nowhere near the level
required to make this a mainstream technology. Maybe it is inherent to the
process itself. I don't see how you can simplify key exchange to make it very
easy for the average user. I guess the price you pay for security is to go
through the pain of figuring out how it works. Of course, most people will not
/ cannot do that even if it is in their best interest.

I'd loved to hear the thoughts of the security gurus on HN about this...

~~~
patio11
_I don't see how you can simplify key exchange to make it very easy for the
average user._

Google/Microsoft/Yahoo posts a blog post containing the following: "PGP keys
for all addresses can be found at
<https://keys.example.com/k/foo%27example.com> . This is recorded in a TXT
record in our DNS in the following easy to understand format.

We invite other mail providers to adopt this standard. We will periodically
check your DNS records prior to sending mail and, if set up properly,
transparently encrypt all mail sent to you."

Essentially, solve key exchange like HTTPS solves key exchange: the user never
has to worry about it.

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Groxx
[summary] Usability study of PGP 5.0. Out of 12 people who didn't know about
private/public key systems initially, but were experienced with email:

Roughly between 1/4 and 1/2 of them (worse in a couple cases) succeeded at a
given task (send a key, encrypt an email, etc). Others failed completely, or
took a long time to achieve it (~30 minutes in several tasks for a couple
people), and some couldn't manage the essentials - even with feedback - by the
end of the 90 minute trial.

Reasons given for the failures were primarily focused around workflow / UI
design.

\---

Strikes me as accurate, probably better than many alternatives at the time,
which is somewhat frightening. And, given my experiences getting signing /
encrypting working in Mail.app, it's hardly improved in the past decade.
Thunderbird makes it simpler, but not by much, and I don't recall being able
to use multiple keys easily.

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dublinclontarf
I recommend building GPG into Firefox along with FireGPG, and suddenly it gets
a hell of a lot easier.

I know most people would be looking at the Thunderbird-Enigmail-GPG route, but
I've found Firefox - FireGPG - GPG to be easier to use, install and more
usefull. Actually the most difficult part with that setup is getting GPG to
play with FireGPG, include GPG with Firefox and suddenly public key encryption
is easy and available to the masses.

~~~
pmjordan
You still have to understand PGP conceptually, though, which is a huge leap
for the average person. FireGPG + GMail is indeed nice, though, although it
seems to be broken half the time.

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dnsworks
At least he learned how to surf.

