[saag] Direct trust between users

[Phillip Hallam-Baker <[e-mail]>]

Nico asked about the Mesh Trust model and I said that I was trying to avoid
imposing one. I do have metrics for measuring the quality of trust
established in terms of a work factor however:

http://mathmesh.com/Documents/draft-hallambaker-mesh-trust.html

This is not a computational work factor as we are used to. It is a social
work factor nominally denominated in currency (USD) and bounded in time.

Let us say that we did some key signing even open to IETF meeting attendees
only. It would cost an attacker $325 plus travel minimum to impersonate me.
Not an impossible sum if they really really want to impersonate me but
enough to stop a large number of attacks. Furthermore, there is a
significant risk of being caught if they attempt the impersonation on any
large scale. So the social work factor might be $1000.

Now lets enroll the assertion provided in a blockchain. We don't need proof
of work to do blockchain. All we need to do is to have multiple notaries
and cross certify between them so that the work factor of each notary
reaches the sum of the work factors of all the blockchains on the planet
within 24 hours. People can do proof of work if they like but nobody can
exceed the work factor of the metanotary because we will add their output
to the metanotary as an input.

I think we can assume the social work factor for metanotary.com is infinity.

So we have an assertion that my public key is MC23-... dated 2019-Jul-18.
It would have cost $1000 to forge that assertion before that date and
$infinity to forge afterwards.

That seems like a useful building block to incorporate into a system of
trust. It is not going to be possible to use that approach in every
situation but we can almost certainly use it in many situations.


So why might we want to do key signing at IETFs?

Well we write code and some of that code ends up on GitHub and makes its
way into software used in the wild. So credentialling IETF-ers would be
pretty useful. Credentialling the Linux Plumbers etc. is probably even more
useful. Probably a good thing if we could do something at Black Hat or RSA.

We could probably deliver a real improvement in the robustness of the
Internet software development ecosystem if we produced a system serving
10,000 or so users and was never used by outside that community.


So how might it work?

I have done a few sketches but I haven't come to a firm conclusion on how
to realize the crypto yet.

The simplest user experience to implement would be to have an app for
mobile devices that can be used to scan a dynamic QR code presented on a
screen near the registration desk. This would provide the necessary crypto
info to complete the key signing.

We could go further and make it so that scanning the QR code tells the
attendee which line to join and causes the registration staff to be told
which badges to find next. The registration staff could then check
government issued ID, hand over the badge and tell the system the ID
matched.