Author Topic: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC  (Read 16527 times)

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Offline Levak

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #30 on: April 14, 2011, 11:15:34 pm »
Basicly :
2 public keys : E and N
1 private key D

We choose X < N
When we encode : y = (X^E) % N
When we decode : z = (Y^D) % N (or the inverse way if you want)
In fact : z = (Y^D) % N
= (X^E % N)^D % N
= (X^E*D) % N
= X^1 % N
= X because X < N

Now, find D with E and N... good luck
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Offline Xeda112358

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #31 on: April 14, 2011, 11:32:39 pm »
Hmm, thanks! I will look at that because it has intrigued me how this works!

Anywho...
Any work I do involving numbers or patterns is my way of just having fun :) They have always been my favorite toys, so I will continue playing with them. The only reason I am working with primes is because they make me happy, not for some silly RSA thing :)

Offline mikehill2003

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #32 on: April 14, 2011, 11:35:42 pm »
Hmm, thanks! I will look at that because it has intrigued me how this works!

Anywho...
Any work I do involving numbers or patterns is my way of just having fun :) They have always been my favorite toys, so I will continue playing with them. The only reason I am working with primes is because they make me happy, not for some silly RSA thing :)

As long as you enjoy it, that's great :D I just wanted you to know how improbable factoring those keys really is.

*mikehill hopes newbies don't think this means they will have the keys in a week....

Offline Xeda112358

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #33 on: April 14, 2011, 11:47:36 pm »
Oh, I know, so thanks :) To brute force a 2048-bit RSA, you might need to check as many as 1+2^1023 numbers as potential factors x.x To give an idea, to those who don't know, that is almost 10^308 which is greater than a google cubed.

Offline perennial

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #34 on: July 30, 2011, 03:31:29 pm »
Can I ask what is the boot1 and boot2 of TI-Nspire 3.0.1.1753?
« Last Edit: July 30, 2011, 03:32:52 pm by perennial »

Offline critor

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #35 on: July 31, 2011, 07:57:34 am »
The boot1 is a program which validates the boot2, decode it and run it. It can also reprogram the boot2, run the diagnostics software, reprogram the diagnostics software...

The boot2 is a program which validates the OS, decode it an run it. It can also run the maintenance menu (remove OS and/or documents) and run a test OS on non-CX models (without permanent installation).


To my knowledge, Boot1 is 1.1.8916 on all non-CX TI-Nspire released.
Boot2 can be 1.1.8981, 1.4.1571 or 3.0.1.131.

Boot1 is 3.0.0.99 on all TI-Nspire CX released.
Boot2 is 3.0.1.131
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Offline perennial

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #36 on: July 31, 2011, 11:54:21 am »
is it 3.0.1.131 for boot2 because on mine it said:
boot1 1.1.8916
boot2 3.1.131
why is the 0 being left out? Is this significant? or just typo from the programmer fault?

Offline Lionel Debroux

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #37 on: July 31, 2011, 12:14:56 pm »
Yes, 3.0.1.131 and 3.1.131 refer to the same version.
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Offline fb39ca4

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #38 on: August 16, 2011, 02:45:00 pm »
So I have a computer with an actual serial port, so for sending the boot2 can I just use that or do I need that specific USB <-> rs232 converter? Also, what program do I need to send the boot2 with?

Also, I need to corrupt my boot2. What memory address do I need to write to to do so?
« Last Edit: August 16, 2011, 02:48:12 pm by t0xic_kitt3n »

Offline Jim Bauwens

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #39 on: August 16, 2011, 02:46:19 pm »
You need a TTL level converter. You can buy them, or make one yourself: http://sodoityourself.com/max232-serial-level-converter/ .
I made mine using the above guide :)
« Last Edit: August 16, 2011, 02:48:00 pm by jimbauwens »

Offline Lionel Debroux

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #40 on: August 16, 2011, 02:55:11 pm »
Quote
Also, what program do I need to send the boot2 with?
A number of terminal programs can do the job. Use the one that critor used, if possible :)

Quote
Also, I need to corrupt my boot2. What memory address do I need to write to to do so?
You don't need to worry about memory addresses, just use the appropriate key combo for the boot1 to put itself in boot2 receiving mode. I don't remember which it is, but it's written in the tutorial :)
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Offline fb39ca4

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #41 on: August 16, 2011, 02:58:26 pm »
No, I need to make it look like my calc is bricked, so I have an excuse to buy a prizm >:D Then, a few months later, I'm going to restore the boot2, and tell my parents "oh, I figured out how to fix it" ;)
Also, what program did critor use? It doesn't say in the article on TI-Bank.
« Last Edit: August 16, 2011, 03:01:14 pm by t0xic_kitt3n »

Offline Lionel Debroux

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #42 on: August 16, 2011, 03:01:11 pm »
Ah, that's a different matter indeed :D
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Offline critor

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #43 on: August 16, 2011, 04:59:34 pm »
The program I used is mentionned in the tutorial linked from the article, with screen captures.
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Offline fb39ca4

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Re: TNOC for OS 3.0 and how to downgrade from 3.0 if you didn't use TNOC
« Reply #44 on: August 16, 2011, 05:08:15 pm »
Huh? The only screenshot I see in the tutorial is of WinRAR. Did you use WinRar to send the file?