2556: Turing Complete
| Turing Complete |
 Title text: Thanks to the ForcedEntry exploit, your company's entire tech stack can now be hosted out of a PDF you texted to someone. |
Explanation
|
This explanation may be incomplete or incorrect: Created by a VIDEO GAME-PLAYING DISHWASHER- Please change this comment when editing this page. Do NOT delete this tag too soon. If you can address this issue, please edit the page! Thanks. |
A Turing Machine is a theoretical form of computer (as an idealised thought exercise) that has an infinite tape of symbols and can act upon and change these values aa it moves up and down this tape according to specific deterministic rules.
This very simple machine can be shown to do every computational task that what we think of as a "computer" can do, given the right setup and enough time. Something that is Turing Complete is able to act as a Turing Machine, though generally with the limitation of having a finite tape, and this means it is also able to do basically every computational task.
While many pieces of hardware and software are supposed to be Turing Complete (even Excel, as previously pointed out in 2453: Excel Lambda), this comic implies that this was not what it was designed for. This presumably means Ponytail has found an exploit allowing for arbitrary code execution. This could be harmless and fun, like running Mario on a dishwasher, or a more serious security vulnerability that a nation-state could use to attack you.
The ForcedEntry exploit is a way that was discovered to allow PDF files to force malware onto various devices. In the title-text it is suggested that this mechanism can be used for what might be more legal and practical purposes, although this might be up to some interpretation depending upon who has the right (and permission) to do what.
Transcript
|
|
This transcript is incomplete. Please help editing it! Thanks. |
[Ponytail and Cueball are standing next to each other] ...Now, it turns out this is actually Turing-Complete... [caption below the panel:] This phrase either means someone spent six months getting their dishwasher to play Mario or you are under attack by a nation-state.
add a comment! ⋅ add a topic (use sparingly)! ⋅ 
refresh comments!Discussion
This is a reference to the new FORCEDENTRY exploit analysis by Google's project zero: https://googleprojectzero.blogspot.com/2021/12/a-deep-dive-into-nso-zero-click.html The exploit runs a full (turing-complete) VM within a PDF decompression algorithm. 172.70.86.68 22:37, 17 December 2021 (UTC)
I don't think "attack by a nation-state" is referring to Turing's WWII work. I think it means a modern nation-state is using FORCEDENTRY to attack you via some unexpected device. Barmar (talk) 23:56, 17 December 2021 (UTC)
- I think it actually is a reference to national security agencies being able to get into your phone and get all your private data and so on 108.162.237.5 01:00, 18 December 2021 (UTC)Bumpf
The explanation should probably also mention that https://googleprojectzero.blogspot.com/2021/12/a-deep-dive-into-nso-zero-click.html was published just two days before this comic. Frank 162.158.94.165 11:09, 18 December 2021 (UTC)
I added in a much needed A Bunch of Rocks reference. I mean, it's a possibly broken Turing Machine (because the operator is 'only human' and occasionally makes mistakes in his process. But, by definition, anything capable of simulating (many!) things that are themselves considered Turing Complete is thus by itself Turing Complete as it carries out (or could carry out) all the tasks that are successfully (or potentially) carried out by them 'on their own'. It's a metaphysical (metaphilosophical? metasomethingorother...) issue, of course. ;) 172.70.91.84 00:29, 19 December 2021 (UTC)
- (Actually, that was before I then went back and fully read ABOR, to fulfill my nostalgia. I forgot that it actually says it is TC in an in-frame footnote. That might be what prompted me to think of it, so forget about me being too clever, it's just true. Voice Of God, etc.) 172.70.91.84 00:34, 19 December 2021 (UTC)
Do things feel more and more like Stross's Accelerando to you as well? 172.68.246.129 09:09, 22 December 2021 (UTC)
Honestly surprised Randall didn't reference Doom in this comic. It's the one game that's synonymous with running on unusual hardware. 172.70.85.79 23:41, 23 December 2021 (UTC)
Weird Machines and Turing Completeness
This comic is closely related to the language security work on weird machines, yes? Could someone more knowledgeable comment?--Philip Romolo Neri (talk) 09:25, 10 January 2022 (UTC)
A Turing tape is unbounded, not infinite. At any given time, only a finite number of symbols have been read or written, but that number can grow without limit over time. In principle, a real-world machine that was able to request more memory whenever it ran out of what it had could be considered equally unbounded - at least if the universe is infinite. Brangdon (talk) 13:14, 23 April 2022 (UTC)
