Anyone aware of this project?

[Alan Karp]

https://github.com/khhodges/church-machine#church-machine

--------------
Alan Karp

[Mark S. Miller]

First I have heard of it. But from a quick skim, looks like it may be interesting.

On Wed, Aug 12, 2026 at 9:06 AM Alan Karp <alan...@gmail.com> wrote:

https://github.com/khhodges/church-machine#church-machine

--------------
Alan Karp

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  Cheers,
  --MarkM

[Alan Karp]

I've invited him to present it to friam, but I haven't heard back yet.

--------------
Alan Karp

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[Raoul Duke]

i personally have not gotten past feeling like "reductio ad auth" -- any capability system w/out authn/authz style components that decide per-process & per-human user (login) powerbox contents, is not a real system, it is hand-wavy. 

[Matt Rice]

On Wed, Aug 12, 2026 at 8:31 PM John Carlson <yott...@gmail.com> wrote:
>
> User-based login powerboxes can be forged.

There is a series of notes on Norm's site
http://www.cap-lore.com/CapTheory/Tartan.html
http://www.cap-lore.com/CapTheory/KK/Keyboard.html etc

which delve into this problem. IIRC tartans reserve an area of the
screen for the system to draw in,
and draw a recognizable pattern negotiated with the user to that area of screen.

I've mentioned in the past avoiding screen reservation by using
programmable rgb keyboards as a tartan.

> Reminds me of problems at UC Davis computer labs in the 80’s, where people would leave hardware terminals going with their own login process running, stealing username+password people would type in.
>
> I’m not sure what you’re saying, but with current systems, 2FA seems best.
>
> John

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[Matt Rice]

On Wed, Aug 12, 2026 at 11:08 PM John Carlson <yott...@gmail.com> wrote:
>
> I’m not sure I understand Norm’s pages (below), so I’m not expecting people to understand mine. No response is okay.
>
> What is typed to get the correct tartan to show up? The account name? Then if I use a rogue login program to capture your account name, i can enter your account to get your tartan (take a snapshot or video of it with my phone, close enough). Once I have your tartan, I need write access to the screen (or keyboard) to display the tartan and complete the rogue login program to get your password/PIN from you. Passwords can be mistyped, “account/password incorrect” can be faked too. Just fake a correct password as an incorrect one, and re-prompt you with the real program. Obviously, computers should be monitored, and rogue programs controlling the screen should be identified. But that’s an arms race.
>

This is why I mentioned reserving a portion of the screen or even a
specific screen explicitly for tartans for the system to draw the
tartan on.
Since this is a reserved drawing area for the system normal programs
are now given the authority to draw to it, and cannot spoof tartans.
Regaining the ability for full screen is exactly why I proposed using
programmable rgb keyboard patterns as a method of drawing tartans.
Under such a scenario the rgb keyboard would be reserved for showing
tartans (spoiling some of the fun of rgb keyboards perhaps).

I believe that the tartan shows up when you input some non-secret
information like your username, but even though others may observe it,
they cannot spoof it on the reserved drawing area.
I'm not certain that tartans need to be restricted to identity. For
instance one might use a specific tartan for their bank.
If I recall there have been similar discussions for browsers, and
spoofing the URL input field/chrome through full screen drawing.

> How do I get the tartan to show up without account identification is the real question. Biometrics and/or write-once media (assuming no fake biometric or fake media reading devices), with a “user arrived” action trigger biometrics/media reading, then bring up tartan, and allow PIN entry for 2FA. I have not heard that “write-any” devices are acceptable.
>
> I know real security systems are more secure, especially layered security. I’m more interested in figuring out how to secure consumer devices.
>
> Perhaps Norm’s notes were written before photo scanners and digital cameras? I’ve only seen image tartans used for one site.
>
> How many people accidentally take many pictures of their tartans spread across their phone gallery? I know fewer share them. Can you say saved to iCloud?
>
> John

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[Matt Rice]

On Wed, Aug 12, 2026 at 11:42 PM John Carlson <yott...@gmail.com> wrote:
>
> Okay, I recall you saying that, but I focused on Norm’s essay. Apologies.

Yeah, I didn't find it when skimming the essays linked either before I
sent them (why I mentioned it, because it seems like a natural
question), but I recall reading it somewhere in the past.


> I’m thinking today’s tartans are the iPhone’s turn on screen, and I’ve grabbed many snapshots of that. I know my wife’s is different from mine.
>
> The key is whether Apple exclusively can show the turn on screen, or of others can as well, perhaps with spoofed pictures from iCloud.
>
> I have seen something that looks similar to Apple’s PIN screen, but without the tartan image. Similarly with Windows Hello, I think. I do think people may be capturing PINs from me. But hey, a bit of pronoia works for that.
>
> John

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[Vinícius dos Santos Oliveira]

Em qua., 12 de ago. de 2026 às 17:51, Alan Karp <alan...@gmail.com> escreveu:
> I've invited him to present it to friam, but I haven't heard back yet.

I hope he accepts the invite. Looks interesting.