[Cryptography] PGP Key Signing parties (Trust Link Grid)

[Ralf Senderek]

On 1 Nov 2013 ianG wrote:

> Let me talk a bit about CAcert and perhaps other CAs as it presents an illuminating
> counterpoint.  CAcert provides that as a network of Assurers.  There are thousands of them
> across the planet, with about a third concentrated in the Germanic belt of countries.

I can understand that you confront my proposal with the established CA-model of
hierarchical key verification. But my proposal does not intend to provide what CAcert
does.

The Trust Link Grid proposal is an invitation to think outside the box to achieve something
the box does not provide. BTW I know the box inside out, as I ran a CA in a former life 
myself. There is (or at least easily can be) a huge amount of first-hand knowledge about
PGP keys that is currently inaccessible and therefore wasted. Bringing this first-hand
knowledge online in the form of trust link statements can help to create trust in keys
that otherwise cannot be linked to someone I know (via key signing parties) in the usual
way.

In regard to the worthlessness of public statements on websites that may put the reputation
of the issuing individual at risk, I stick to a totally different point of view.

Before answering questions what can go wrong, I'd like to point out what you can gain
from the initiative.
Anyone who wants to create trust in his PGP key can collect trust link statements for his
key from nodes and can publish them on his own website. Of course one such statement
means nothing, as it can be the result of a conspiracy with one node. But with every
additional trust link statement (there are four nodes in easy reach of an individual)
the risk of a conspiracy reduces. There can be cross links between more distant nodes
and any of them add to the reliability of the key with their own TLS.

How would anyone succeed in establishing a faked key and trick the public into using it?

1) create a faked public key for the victim (easy)
2) hack the victim's website and replace all trust link statements with forged ones
    that verify correctly with all the right keys the nodes are using (requires conspiracy)
3) make sure that the victim does not upload an additional trust link statement from
    a different node as this would make the plot detectable.

Seems reasonably difficult to me. On the other hand it's easy for anyone to examine the
trust link statements online to make an informed decision whether or not a key can be
trusted, without having a direct trust chain (via key signing parties) which might not exist.

Worthless? Not at all.