Thursday, December 08, 2005

Re: X.509 / PKI, PGP, and IBE Secure Email Technologies

On Wed, Dec 07, 2005 at 09:42:03AM -0500, Ed Gerck wrote:
> To help develop a common yardstick, I would like feedback (also by
> private email) on a list of desirable secure email features as well
> as a list of attacks or problems, with a corresponding score card for
> the secure email technologies X.509 / PKI, PGP and IBE. The paper
> is at

What's missing, except implicitly, is the most important feature of
all. Ease of use and deployment. What do users have to _do_ to get
the software, to get and maintain certificates (if required), and to
send and receive mail.

This is the most important feature because inattention to it has
caused both secure and insecure systems to not get used except by
a small minority of the population. That the system be easy enough
to use that people will actually use it turns out to be as important
as how secure the system is against various threat models. More
important than security against certain more rare threat models.

It's amazing how easy it is to get this wrong. Did you know that
Microsoft Outlook, the most common email program in the world, has
opportunistic e-mail encryption if you
a) Get a certificate (free from thawte)
b) Click two checkboxes

Nobody uses it because of one very simple but giant mistake. If
you turn on the checkboxes, then every time you send mail and
every time you receive encrypted mail, you get a dialog box popping
up asking to confirm if the program can access your private key.

(Also, nobody knows about it, and it uses giant ugly x.509/s-mime)

And one final note -- it is controversial to describe "return receipt"
as a feature. For recipients, that's an anti-feature.

Brad Templeton

1 comment:

Ed Gerck said...

Ease of use and deployment is now explicitly there, at the end of Section 1.

You make a good point -- why aren't we there yet? . Well, after almost 15 years (Zimmermann created the first version of PGP in 1991) we should have reached the diminishing returns plateau after so many years of feedback and new versions. And yet, PGP version 5 was so difficult to use that when test participants were given even 90 minutes in which to sign and encrypt a message, the majority of them were unable to do so successfully (see Section 1 ref.)

As I see it, to solve the usability problem not even another 30 years
will help. What's needed for improved usability is much less. Before any work on yet another improved graphical user interface and more help text to guide the user through all the steps required to send and receive secure email, what's needed is a real reduction and simplification of those steps.

This is another motivation for the paper, with a view to both improve the email security technologies X.509 / PKI, PGP and IBE, and develop the specifications for new technology beyond current limitations -- including
ease of use and deployment.

You make two good points why nobody uses email encryption, even thouhgh it's part of Outlook and you can get a free PKI certificate. I started a discussion on this subject with the paper "What Email Needs, Part I" here at .

IMO, the reason why encryption is not used (and, btw, PGP is free too) lies deeper and is yet very simple. It will be in Part II, coming shortly.

About your final note, that it is controversial to describe "return receipt" as a feature, because for recipients that's an anti-feature.

Yes, but only if the recipient is not notified beforehand and cannot choose what to do (just like postal mail with signature on delivery -- either you sign or you don't get the package).

To clarify, I added the note:

(**) To allay privacy concerns, the recipient should be informed beforehand that the Return Receipt will be sent back to the sender if the recipient decrypts the message. If the recipient wishes to decline to provide the receipt, the recipient should not attempt to decrypt the message.

Ed Gerck