[Mathmesh] Configure SSH with UDF key...

Phillip Hallam-Baker <phill@hallambaker.com> Sat, 28 September 2019 22:16 UTC

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From: Phillip Hallam-Baker <phill@hallambaker.com>
Date: Sat, 28 Sep 2019 18:16:23 -0400
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Subject: [Mathmesh] Configure SSH with UDF key...
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I am just writing a series of presentations on the Mesh to put out to
podcast to explain the concepts and the technology. The Mesh presents four
technologies that in combinations can solve a large number of difficult

UDF is the one Mesh technology that does not depend on any other and I keep
finding new uses. And the latest of these is to configure SSH.

The biggest hassle with SSH is how to install your private key on each of
the devices that you want to use it from. In theory of course, you want to
have an independent key for each device so that you are not completely
hosed if you lose one of them or you are passing through an airport and
someone demands you login to your laptop.

But most people have one private key and they move it from one machine to
another in email. Oh and 'most people' probably isn't most of the people
here. It only takes one pinhead to bust a hole in your corporate defenses.

So I have been looking at recovery mechanisms for Mesh profiles. And one
very promising approach is to use a KDF and a strong password to generate

KDF ("ZAA2-UJUY-H7TF-SFLK-CWAW-TKC4-O5HQ-GIYA", "mmm_master_signature")
KDF ("ZAA2-UJUY-H7TF-SFLK-CWAW-TKC4-O5HQ-GIYA", "mmm_master_escrow")

So the encryption and signature keys are generated from Z

All we need to do now is to escrow ZAR2-UJUY-H7TF-SFLK-CWAW-TKC4-O5HQ which
we can do by Shamir Secret sharing.

What if we could also do


Now we have a really quick way to reconstitute the authentication key on
each of the user's devices.

What I was thinking of for implementation is to define a new type code,
probably 200 which gives an initial letter of Z. Then make the following
two bytes a 16 bit registry code saying what the key is to be used for
(Mesh, SSH, etc.)


As with passwords, we might well need to help people follow their current
workflow in a not quite so stupid fashion before we try to change it.