An anonymous reader writes "Texas Instruments' most recent, ARM-based series of graphing calculators, the TI-Nspire line, has long resisted users' efforts to run their own software. (Unlike other TI calculator models, which can be programmed either in BASIC, C, or assembly language, the Nspire only supports an extremely limited form of BASIC.) A bug in the Nspire's OS was recently discovered, however, which can be exploited to execute arbitrary machine code. Now the first version of a tool called Ndless has been released, enabling users, for the first time, to write and run their own C and assembly programs on the device. This opens up exciting new possibilities for these devices, which are extremely powerful compared to TI's other calculator offerings, but (thanks to the built-in software's limitations) have hitherto been largely ignored by the calculator programming community."
The keys are not required to access the binary. There is no encryption; the keys are just to verify that the OS image hasn't been corrupted. The entire binary has always been completely accessible from both the PC side (before transferring) as well as on the calculator. Furthermore, the community has had the ability to load its own operating systems on the TI-83 Plus since 2002. TI had stated in 2004 that they had no problem with independent third-party OSes being loaded, as long as (understandably) no one distributed modified TI OS files. The only new development here is that third-party operating systems can now be loaded onto the calculators without any hacks or preparation. In other words, they can be loaded in a user-friendly manner like the TI OS is loaded, and transmitted from calculator-to-calculator without having to run a special program beforehand. This is a huge deal in gaining acceptance for third-party operating systems, because end users do not want to have to pull out a battery during validation or run a strange program before loading the OS. They'd rather just click and be done.
An anonymous reader writes: A month ago, ticalc.org reported smart factoring of the 512-bit RSA key used by TI to sign their TI-83+ OS, which opens the door to seamless installation of open-source third-party OS on TI-83+ calculators. Since then, two other keys found in other TI calculators have been factored by a distributed effort. Several days ago, TI sent DMCA takedown notices to several sites mentioning the keys and their factors. All three keys factored so far have been posted to Wikileaks, and the effort to factor the remaining ones is going on.
Link to Original Source
Link to Original Source
Cubeman writes: "The 512-bit RSA key protecting the operating system of TI-83 Plus and TI-84 Plus calculators has been cracked! Benjamin Moody posted the factorization yesterday, and it has been verified by Brandon Wilson. With the RSA key broken, developers can now release cryptographically signed third-party OSes which will validate on any unmodified calculator. While TI's security protections have previously been broken, all prior hacks required loading an extra program on each calculator. This broken OS key means that the last frontier of TI hacking has finally been achieved. Calculator programmers now have complete control over every area of the calculator and can write any code in any form, even entire operating systems, and distribute them freely on any 83+/84+ calculator in existence. ticalc.org has an article about this as well."