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Offline Lionel Debroux

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Re: TI-Nspire emulator
« Reply #75 on: November 14, 2011, 03:05:07 pm »
Yeah, we'll probably have to tell a significant number of people that they need to perform their own dumps, when they can.
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Offline ExtendeD

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Re: TI-Nspire emulator
« Reply #76 on: November 15, 2011, 08:28:13 am »
(*): embedding the boot2 decryption code into the emulator is not possible: circumventing protection measures would easily fall under the DMCA, and this time, TI would have a better case than they did for the signing key fiasco.

Would it be more than a few calls to OpenSSL functions?
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Offline Lionel Debroux

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Re: TI-Nspire emulator
« Reply #77 on: November 15, 2011, 10:55:46 am »
If it's similar to the other pieces of the encryption infrastructure, indeed, decrypting the boot2 wouldn't require more than several calls to OpenSSL functions. However, my understanding is that even distributing the decryption key(s ?) isn't perfectly legal in some countries (for questionable reasons, but it's the law) :(
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Offline lkj

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Re: TI-Nspire emulator
« Reply #78 on: November 15, 2011, 11:32:25 am »
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(*): embedding the boot2 decryption code into the emulator is not possible: circumventing protection measures would easily fall under the DMCA, and this time, TI would have a better case than they did for the signing key fiasco.
But aren't the os update files (.tnc/.tno) also encrypted in a weird way? And the imgdump tool was distributed without legal problems?

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2) this hurdle will eventually be overcome in the future (like on pretty much any closed platform in the past two decades), but the result cannot be redistributed: the boot1 contains TI's copyrighted code...
I know the old boot1 was available on the internet because I've downloaded it myself, but that's certainly illegal.

Offline Lionel Debroux

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Re: TI-Nspire emulator
« Reply #79 on: November 15, 2011, 11:43:49 am »
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But aren't the os update files (.tnc/.tno) also encrypted in a weird way?
They're ZIP files with a weird header; the boot2 (if any) is compressed with a non-standard format; the OS is encrypted with a symmetric cipher whose name evocates fish.

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And the imgdump tool was distributed without legal problems?
Well, the original author of imgdump removed all references to imgdump from his own posts, and all copies of imgdump able to decrypt the OS.
« Last Edit: November 15, 2011, 11:47:16 am by Lionel Debroux »
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Offline lkj

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Re: TI-Nspire emulator
« Reply #80 on: November 15, 2011, 12:01:38 pm »
So this means the current imgdump can't produce phoenix.raw files anymore?

Offline Lionel Debroux

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Re: TI-Nspire emulator
« Reply #81 on: November 15, 2011, 01:58:57 pm »
The version of imgdump that supports only the boot2 decompression cannot produce phoenix.raw files anymore, indeed.
The other method for decompressing a Clickpad/Touchpad OS, which involves running the Clickpad/Touchpad boot2 in an arm-none-eabi-gdb, keeps working.
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Offline lkj

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Re: TI-Nspire emulator
« Reply #82 on: November 15, 2011, 03:42:59 pm »
Then I myself have a copy of the old imgdump.

Offline Lionel Debroux

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Re: TI-Nspire emulator
« Reply #83 on: November 15, 2011, 03:52:45 pm »
Keep it preciously :)
Even if it wouldn't help for CX and CM OS, since they have got different decryption keys, one unique key per {calculator type, OS version} pair.
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Offline migasbr

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Re: TI-Nspire emulator
« Reply #84 on: November 18, 2011, 12:26:56 pm »
OSLauncher just launches the other OS, it does not install it in any way; just reboot the calculator and the effect of OSLauncher is gone :)

So I tried do install the OSLauncher... But because I'm a NOOBBB... I updated the SO when I purchase the calc... That means right now I have the "deadly" SO 3.1 and I'm stuck!...

I tried to find a solution to do a downgrade with this SO and found a software called TNOC that claims that removes the boot2 from the SO and generates a new file without the boot2. Tried that and installed the SO generated by TNOC but didn't find any difference and couldn't do the downgrade..

Then I also read that there is a way to "crash" the SO by installing it and during the instalation, swap the keypad to the TI-84 and swap back again.. or something like that..
That should crash the SO and then should be able to install any SO.. Well, I don't have the TI-84 keypad to try this, but I notice that Texas in Portugal was offering these keypads to whom purchased an Nspire calc... But that promotion was only untill June! (how lucky am I?...  <_< )... I've sent the coupon anyways, together with a nice letter see if I can convice them to send me the keypad!....  ::)

In the meantime, do you have any other sugestions of how to "kill the beast" SO 3.1?... 

Offline Lionel Debroux

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Re: TI-Nspire emulator
« Reply #85 on: November 18, 2011, 12:41:37 pm »
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That means right now I have the "deadly" SO 3.1 and I'm stuck!...
Yes, completely stuck, at the time of this writing...

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I tried to find a solution to do a downgrade with this SO and found a software called TNOC that claims that removes the boot2 from the SO and generates a new file without the boot2. Tried that and installed the SO generated by TNOC but didn't find any difference and couldn't do the downgrade..
Well, TNOC avoids installation of the newer boot2 (with more lockdown) on calculators that still have the old boot2, but is obviously powerless for calculators which already received said newest boot2 through unmodified OS upgrades :)

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Then I also read that there is a way to "crash" the SO by installing it and during the instalation, swap the keypad to the TI-84 and swap back again.. or something like that.. That should crash the SO and then should be able to install any SO.
No, not at all: even if you erase the OS completely, the anti-downgrade protection enforced by the boot2 won't allow you to downgrade to any OS version supported by Ndless - and thus, to use OSLauncher.

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In the meantime, do you have any other sugestions of how to "kill the beast" SO 3.1?...
I don't, because there's no way to do that ;)
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Offline renatose

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Re: TI-Nspire emulator
« Reply #86 on: November 18, 2011, 01:50:53 pm »
Couldn't the downgrade be done using a TTL connection?

EDIT: if migasbr is in the region of Lisbon I can help him doing that, because I've got one.
« Last Edit: November 18, 2011, 01:52:07 pm by renatose »

Offline Jim Bauwens

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Re: TI-Nspire emulator
« Reply #87 on: November 18, 2011, 01:56:46 pm »
I think its possible to downgrade the boot2 through the serial port (TTL), and then use downgradefix to remove 3.1.
But I'm not entirely sure.

Offline Lionel Debroux

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Re: TI-Nspire emulator
« Reply #88 on: November 18, 2011, 03:27:30 pm »
If you manage to downgrade the boot2 to 1.4, indeed, you can use DowngradeFix, and the serial port lets this downgrade happen (critor did it on Levak's calculator shortly after the release of OS 3.0.1.1753)... but only a tiny minority of people have a USB TTL adapter, and I focused on solutions that don't require extra hardware.

I stand corrected, though - I should have mentioned the serial port :)
« Last Edit: November 18, 2011, 03:28:36 pm by Lionel Debroux »
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Offline renatose

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Re: TI-Nspire emulator
« Reply #89 on: November 18, 2011, 06:25:50 pm »
I won't risk putting boot2 v3.xxx on my nspire cuz I don't want to live with the impossibility to downgrade to OS 2.1 however it looks that ndless3 is near from being out. So maybe it is wiser to wait a while and try all Lua programs out there until it is out that to spend the time and effort on downgrading for nothing...