[Acme] User Experience criteria

[Phillip Hallam-Baker <[e-mail]>]

One of the important features of LetsEncrypt that we must not lose sight of
is the ease of use goal.

99% of the pain involved in PKI today is unnecessary. I timed myself
installing S/MIME certs in various email clients and it took between
fifteen and thirty minutes. And I know what I am doing (unlike the typical
user).

Easy to follow instructions invariably turn out not to be for a large
number of reasons. Not least the instructions are usually out of date. So
while they might be simple they are also WRONG.

Lab testing is useful but it can also be a cop out. The behavior of a paid
test subject in a fifteen minute test rarely reflects that of a real user's
daily use. It is very informative for sales though.


I have been working on fixing this for S/MIME and I have written a program
that will configure Windows Live Mail to use S/MIME with no user input at
all. This is very similar to the planned user experience for Lets Encrypt
but it would be good if we could get the objectives down and generalize
them.


1) User interaction is only permitted for the purposes of
1a) Obtaining information that only the user can provide
1b) Providing information to the user

2) All information necessary for the user to make a decision will be made
available.

3) Adding security should require no additional user effort.


The first one is the key. The user should never have needed to do anything
more than say what their CA is and provide any necessary validation data.