Failure of PKI in messaging

Ben Laurie ben at
Tue Feb 13 10:10:08 EST 2007

Ian G wrote:
> Steven M. Bellovin wrote:
>> On Mon, 12 Feb 2007 17:03:32 -0500
>> Matt Blaze <mab at> wrote:
>>> I'm all for email encryption and signatures, but I don't see
>>> how this would help against today's phishing attacks very much,
>>> at least not without a much better trust management interface on
>>> email clients (of a kind much better than currently exists
>>> in web browsers).
>>> Otherwise the phishers could just sign their email messages with
>>> valid, certified email keys (that don't belong to the bank)
>>> the same way their decoy web traffic is sometimes signed with
>>> valid, certified SSL keys (that don't belong to the bank).
>>> And even if this problem were solved, most customers still
>>> wouldn't know not to trust unsigned messages purporting
>>> to be from their bank.
>> Precisely.  The real problem is the human interface, where we're asking
>> people to suddenly notice the absence of something they're not used to
>> seeing in the first place.
> Actually, there are many problems.  If you ask the low-level crypto
> guys, they say that the HI is the problem.  If you ask the HI guys, they
> say that the PKI concept is the problem.  If you ask the PKI people,
> they say the users are not playing the game, and if you ask the users
> they say the deployment is broken ...  Everyone has got someone else to
> blame.
> They are all right, in some sense.  The PKI concepts need loosening up,
> emails should be digsig'd for authentication (**), and the HI should
> start to look at what those digsigs could be used for.
> But, until someone breaks the deadly embrace, nothing is going to
> happen.  That's what James is alluding to:  what part can we fix, and
> will it help the others to move?
> iang
> ** I didn't say digital signing ... that's another problem that needs
> fixing before it is safe to use, from the "ask the lawyers" basket.

Perfectly safe to use in the UK. But sorry, I forgot that only the US


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