Failure of PKI in messaging

Ed Gerck edgerck at
Tue Feb 13 19:21:50 EST 2007

The solution is simpler than it seems.

Let's first look at one scenario that is already working
and use it as an example to show how the email scenario
may work.

Banks are already, and securely, sending and receiving
online messages to/from their clients. This is done by
a web interface, after the user logs in to their account.

Web user login can be based on a number of two-factor and
mutualauthentication solutions, some of them quite ineffective
to prevent phishing but, nonetheless, better than what the
email PKI model provides.

What's missing with the email PKI model?

While the bank is asking to be authenticated by the user, it
does so by asking the user to rely on a number of third-party
references that are actually unreliable (ie, by being without
recourse, warrantless, unverifiable, and chosen by the purported
sender in what may be a con game). The bank would never allow
the user to be authenticated under the same assumptions!

So, what's missing in the email PKI model is two-sidedness.

It is essential to have a reference point that the user trusts.
In the web messaging example already used by banks, this is
provided by the user login -- the user trusts that that is their
account -- their name is correct, their balance and transactions
are correct.

I am using this insight in a secure email solution that provides
just that -- a reference point that the user trusts, both sending
and receiving email. Without such reference point, the user can
easily fall prey to con games. Trust begins as "self-trust". Anyone
interested in trying it out, please send me a personal email with
application info.

Ed Gerck

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