yeah if the viruses got updated regulary the antivirus updates could get much harder and could even overhelm the author with work.

Oh let's not get started with OS fanboyism here it got pretty annoying on IRC a few weeks ago. If you be careful on Windows (such as not using IE and watching out what you download) you won't get much viruses anyway.

As for calcs yeah they're very uncommon. And if someone make a bad ASM program he can simply rename it to Mario or Galaxian and make it the exact same size as the original game. All he has to do is use bad Axe Parser code then put loads of data at the end of his program, enough so the file is the same size. I am sure some detection could be done code-wise, though, but it would still be hard

Well, I need a list of bad hex codes. Ones that are malicious. Without them, I can't do it.

This above program is nearing completion. While it will be some time before it is available for beta testing, I am posting here to ask if anyone is willing to beta test when the time comes. If you want to participate, please post so here, and provide a VALID email address. Thank you.

Unfortunately, since I am slowly returning from some break and might be busy with some stuff outside the community such as some games (*cough*Starcraft II*cough*) and my calc project, I don't think I'll have time to test this, especially that I do not know assembly programming or anything that would allow me to figure out how to find security breaches in your program.

That said I'll be honest with you. I do not mean to be rude and I generally don't do this when it comes to calc projects, but like Shmibs is implying, I do not really see the use of a calculator anti-virus. Maybe inside school, where students who barely know anything about calcs can get infected with some sort of Ion-virus renamed to Phoenix or risks of running programs like OSKill, also renamed to popular game names, it could be useful to have on someone's calc, but online, in the TI community, I personally doubt anyone with minimal calculator knowledge will want an anti-virus on their calc, especially that ASM programmers can easily modify their program to circumvent the protections you would need to keep updated regulary. Another issue is that a virus needs to be on a popular archive to be popular. This means ticalc.org. However, ticalc.org deletes such file from their archives. Hence why Iambian's Ion infector program (I forgot the name and URL) as well as BrandonW's OSKill program are not available there.

I noticed that since you joined the forums, you have a huge dedication in such programs, and it can be seen by how you resumed work on Blast Antivirus after most of us thought it was dead. However, I think that in long terms, persisting in creating such program could ruin your TI programmer reputation (like what happened to KermMartian between 2002 and 2004). Once a reputation is ruined, it is hard to repair it afterward. On certain other sites, you may get an even harsher response to an anti-virus project, or the thread may be turned into a troll fest in a day, as people will not take its author seriously anymore. Most people will think you only make useless programs or programs that were done 100000 times before and flood the ticalc.org archives with them, and people in the TI community often suggested to ticalc.org to stop allowing said "anti-viruses" and "Windows XP" clones in their archives, because about 90% of the archives are made of those (as well as Quadratic Solvers and Number Guessing Games). In the past, I was one of those people. Later, I simply stopped visiting TI-83 Plus BASIC Misc. Programs altogether, until Ticalc.org split them in sub-directories.

I think that once this project is done, you should maybe focus on something that would be more useful to the average Omnimaga/Cemetech/UTI/etc user and that hasn't been overdone either in the past decade. Examples would be games (like the Star Trek game you had in the works a while ago) or programming tools (like your TI-BASIC tutorials, providing they are made to provide a way of learning that other tutorials don't). That's unless your audience is meant to be people at school, but then still remains the issue that programs for school users may not really attract attention on a site like Omnimaga. As you could notice already, even math programs have an hard time getting attention on Omnimaga as well. The thing is that the average crowd here is only interested in games and tools to develop games.

Of course that's up to you, though. I am just giving a suggestion. I would like to see at least one anti-virus for calcs that actually work and do something, even if it's to protect against Iambian's and BrandonW.

Also, I merged your 3 anti-virus threads together and moved them to calc projects and ideas, since I felt one was enough.

Just to repeat a couple things you are probably already aware of:
This is extremely difficult, especially since a person who was really trying to be malicious could simply disassemble, slightly change, then reassemble the code, which would render your checks inoperable.
As for RAM restore, realize that this can only be done on the 83+SE and older 84+(SE)'s, because newer ones (and any normal 83+) do not have the RAM required to backup the main 32KB of RAM.
Anyway, ignore my skepticism and good luck! (Do be aware of the reputation damage that could be done, though, like DJ said)

The main problems that I see though are that I'm not sure you can really block everything. If I wanted to, I could make a bad program, decrease every byte by one, and send it to someones calc. Your program wouldn't even pick up a single bcall because in it's current state, there are none. But then when it is run, it increments all the data and runs.

Not to mention, I found a way to invalidate an os, (in my case, erase page 0) with 7 bytes. I could make a 3k program that slowly through a process does those commands. I could add $70 + $0F to get $7F. Then use out (06), a, to bring in flash page $7F which is the boot code. Finally, add $4300 + $0014 to get $4314 which I could use jp (hl) to hide. I just don't see how you can protect against everything.

The best thing you could do is probably get some people to write bad programs for you to test your anti-virus on, but of course make sure to test on emulator first, and watch out about programs that deletes the certificate

Reading this I think to myself, "I just disassembled the boot code yesterday... I know how to do this!"