A mighty fortress is our PKI, Part II

[Nicolas Williams]

On Wed, Jul 28, 2010 at 11:13:36AM -0400, Perry E. Metzger wrote:
> On Wed, 28 Jul 2010 09:30:22 -0500 Nicolas Williams
> <Nicolas.Williams at oracle.com> wrote:
> 
> I have no objections to "infrastructure" -- bridges, the Internet,
> and electrical transmission lines all seem like good ideas. However,
> lets avoid using the term "Public Key Infrastructure" for things that
> depart radically from the Kohnfelder and subsequent X.509 models.

Well, OK.  But PKI no longer means that, not with bridges and what not
in the picture.

> > Infrastructure (whether of a pk variety or otherwise) and transitive
> > trust probably have to be part of the answer for scalability
> > reasons, even if transitive trust is a distasteful concept.
> 
> Well, it depends a lot on what kind of trust.
> 
> Let me remind everyone of one of my long-standing arguments.
> 
> Say that Goldman Sachs wants to send Morgan Stanley an order for a
> billion dollars worth of bonds. Morgan Stanley wants to know that
> Goldman sent the order, because the consequences of a mistake on a
> transaction this large would be disastrous.

Indeed.  They must first establish a direct trust relationship.  They
might leverage transitive trust to bootstrap direct trust if doing so
makes the process easier (which it almost certainly does, and which we
use in the off-line world all the time using pieces of paper or plastic
issued by various authorities, such as "drivers' licenses", "passports",
...).

> > However, we need to be able to build direct trust relationships,
> > otherwise we'll just have a house of transitive trust cards.
> > Again, think of the the SSH leap-of- faith and "SSL pinning"
> > concepts, but don't constrain yourselves purely to pk technology.
> 
> I believe we may, in fact, be in violent agreement here.

We are.  Perhaps I hadn't made my point obvious enough: transitive trust
is necessary, but primarily as a method of bootstrapping direct trust
relationships.  I really should have used that specific formulation.

Nico
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