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

Bill Stewart bill.stewart at pobox.com
Fri Dec 9 18:39:04 EST 2005


At 09:40 AM 12/8/2005, Aram Perez wrote:
>On Dec 7, 2005, at 10:24 PM, James A. Donald wrote:
>>Software is cheaper than boats - the poorest man can
>>afford the strongest encryption, but he cannot afford
>>the strongest boat.
>
>If it is that cheap, then why are we having this discussion? Why
>isn't there a cheap security solution that even my mother can use?

Usability is a hard problem, and security is a really broad field.
PGP, for instance, did a pretty good job of security a decade ago,
given Phil's threat models, (ignoring a few algorithm problems
that were mostly related to trying to skimp on bits
and the subsequent weaknesses in MD5),
but the usability was pretty rough back then,
and version compatibility has gotten enough worse that
Hugh Daniel and I can no longer reliably communicate with PGP.

But even if we both drop back to GPG on text files,
and use remailers run by friends on Tor nodes run by random strangers,
KGB-proof security would require protection against
black-bag jobs on Hugh's keyboards and duping employees
at my company's IT department into weakening my Windows XP configuration.
(For cost-effectiveness and avoidance of detection,
I'd recommend the latter strategy, probably by selling them
some new nifty administration tool or Instant Messaging client :-)

The real security issue for your mother is threat models.
If your mom isn't using a Mac or administering her own Linux box,
then her biggest security threat is that she's computing
on a box made of Swiss cheese (though XP does seem to be
noticeably better than Win95/98/ME) and probably using a browser
that's happy to accept random software installed by spammers
and phishers, and if she's not using webmail,
she's probably running a mail client that happily displays
clickable links to phishing sites purporting to be eBay or her bank.
And that's mostly independent of whether she can trustably
send email to other members of the Ladies' Sewing Circle and
Terrorist Society without the Feds reading it,
which is the kind of problem PGP was trying to solve,
because her bank and eBay don't cryptographically sign their mail.

Popularity of a product is critical to its security;
you don't gain anonymity if the Feds can recognize that
you're one of the dozen users of a given application.
Your mom can use Skype, but nobody she knows uses Crypto Kong,
and I only know a few people who use PGP to email their mom.
But some of the Instant Messaging systems use crypto;
too bad that they're continually trying to be incompatible
with each other to gain market share.


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