I sent an email to a contact at TI about this thread, we'll see what comes of it (maybe nothing considering this is not their area, but maybe they can forward the email to someone else). Anyway, I'll let you know.

I agree TI Care's response about basically using exploit-needing community tools is both hilarious and sad.
If you absolutely need to downgrade and are decent with Linux, you can use a program called flashrom on a Raspberry Pi (any model, really) with something called a Pomona clip (SOIC-8) attached directly to the calculator's memory chip to manually force a downgrade. I can confirm this method actually works, but I had the foresight to backup my calculator's ROM before upgrading; consequently, I never wrote the code needed to modify a ROM for downgrading (as opposed to just restoring a backup). But if you feel bold and confident enough to disassemble your calculator and don't mind buying the requisite hardware, I can privately guide you through the process.

It's technically possible to use a $4 Pi Pico instead of a full $35 Pi, but I haven't researched that and you may be on your own.

I figure this doesn't upset the d├ętente because any student who can use engineering test equipment to hack their calculator probably doesn't need to cheat.
Well, a software way exists too, it's just not public. Probably easier for this person to be privately given the right tool to go back to 5.6.0 since that's the legitimate exam usecase...

Anyway, the TI person replied, they are now aware of the issue, so we can assume it'll be escalated.
Bad News: OS 5.6.1 not allowed for exam use. Exam Board not gonna update the thing cos TI in Singapore won't. CERMASTR 3.0 also blocked downgrade. Looking like I need to buy a new one
You can try to get in touch with critor directly (no promise, but 5.6.1 -> 5.6.0 isn't something that would help anyone cheat AFAIK...) maybe he can help you, since TI apparently isn't able to...
It really bugs me that TI makes an OS you can't downgrade, publishes it on their website without warning people that it isn't allowed in certain countries, and then doesn't even really attempt to help fix the problem. Mad
Like apparently TI has a webpage for Singapore OS and apps only but there's no SG website for TI. Then I keep on getting redirected to US website where the entire thing started off
What if we found a way to edit the ROM in a hex editor? Maybe someone could find bytes that could be changed to allow downgrading. Though doing such a thing would be dangerously risky.
ShinyGardevoir wrote:
What if we found a way to edit the ROM in a hex editor? Maybe someone could find bytes that could be changed to allow downgrading. Though doing such a thing would be dangerously risky.


That's pretty much exactly what Bootswap does when you hit "disable OS protection" - the issue is that Bootswap doesn't work on 5.6.1, so there's no way to flash a ROM to the device without using a hardware flash programmer.

Anyways, the issue isn't that we can't write a downgrade tool (CERMASTR would work as one if not for code specifically preventing that) but that we won't, as it seems that TI has implied that they only left the arTIfiCE exploit in on the condition that we don't release downgrade or other exploits.
It is possible (you have the hardware, it is just about modifying the software, so technically any software-implemented restriction should be bypass-able). However, due to the fact that many people don't want to disassemble the calculator and work with machine code that is written in the calculator's hardware to manually override any restrictions preventing a software downgrade, it is very hard to bypass those restrictions. However, with enough time and resources, I don't see why this shouldn't be possible. If time is a shortage, then you can even give the source code of the current OS of the calculator to an Artificial Intelligence (such as gpt-3), and have it find vulnerabilities that may allow you to downgrade the operating system version for the calculator, and if you don't want to spend too much time, you can even ask it to give you step-by-step instructions on how to downgrade the version using one of the vulnerabilities that it may have found. Good luck trying to downgrade the operating system version. P.S. I feel like the upgrades to the ti-84 operating system are more like downgrades, and are removing existing features instead of adding newer ones.
Sans_Nom wrote:
If time is a shortage, then you can even give the source code of the current OS of the calculator to an Artificial Intelligence (such as gpt-3), and have it find vulnerabilities that may allow you to downgrade the operating system version for the calculator, and if you don't want to spend too much time, you can even ask it to give you step-by-step instructions on how to downgrade the version using one of the vulnerabilities that it may have found.


This gave me a chuckle. I don't think that AI will be able to accurately identify vulnerabilities in code. The code for the OS is sooooo... large, and the maximum input size for ChatGPT is (I think) probably on the range of kilobytes at best. More likely, code generation in ChatGPT can be exploited by malicious people to create code with intentional flaws and/or backdoors. Anyway, how would you get the source code of TI's own OS? You would have to be high-up in the company to even recieve source code.
Sans_Nom wrote:
It is possible (you have the hardware, it is just about modifying the software, so technically any software-implemented restriction should be bypass-able). However, due to the fact that many people don't want to disassemble the calculator and work with machine code that is written in the calculator's hardware to manually override any restrictions preventing a software downgrade, it is very hard to bypass those restrictions. However, with enough time and resources, I don't see why this shouldn't be possible. If time is a shortage, then you can even give the source code of the current OS of the calculator to an Artificial Intelligence (such as gpt-3), and have it find vulnerabilities that may allow you to downgrade the operating system version for the calculator, and if you don't want to spend too much time, you can even ask it to give you step-by-step instructions on how to downgrade the version using one of the vulnerabilities that it may have found. Good luck trying to downgrade the operating system version. P.S. I feel like the upgrades to the ti-84 operating system are more like downgrades, and are removing existing features instead of adding newer ones.


As I mentioned before, finding exploits is not the limiting factor here.

Like clevor said, GPT-3 is extremely poorly suited for this type of thing. It's a language model, which means that it's designed to operate on a relatively small block of text. Finding exploits in something requires you to look at the system as a whole and determine what assumptions the developers made that security depends on, and then find ways in which that assumption is invalid. It's also tremendously helpful to be able to run the code while looking for an exploit. GPT-3 might be able to find trivial buffer overflows or use-after-frees in a short snippet of C source code, but for a large program like TI-OS for which the source code is not available and in a weird assembly language it's absolutely not going to be able to find anything.

But yes, the best form of downgrade protection for TI at this point would just be to make sure that the set of features monotonically increases with OS version, and then nobody would even have a reason to look for an exploit in the first place.
Building on what commandblockguy said: The exploits/tools necessary are already there, anyone with the proper knowledge and a free afternoon could easily create a downgrade tool. However, because of an (unspoken?) agreement with TI, the community doesn't want to release things which could A) make cheating easier and B) anger TI. Since you can run assembly on the latest OS with arTIfiCE anyway, it's not really that big of an issue.
  
Register to Join the Conversation
Have your own thoughts to add to this or any other topic? Want to ask a question, offer a suggestion, share your own programs and projects, upload a file to the file archives, get help with calculator and computer programming, or simply chat with like-minded coders and tech and calculator enthusiasts via the site-wide AJAX SAX widget? Registration for a free Cemetech account only takes a minute.

» Go to Registration page
Page 2 of 2
» All times are UTC - 5 Hours
 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

 

Advertisement