New G2 HP Prime

[debrouxl]

Hi Claudio

Quote:For real?

Well, yes, unfortunately. If it weren't, I wouldn't dare posting such fake news
critor noticed that the OS upgrade process now contained three phases: "Verifying OS", "Preparing OS" and "Upgrading OS". Then, he tried to modify a byte in the embedded Tunnel.prgm sample: the OS upgrade failed the validation, and the process aborted. See https://ti-pla.net/p234280 and subsequent posts, in French.

Quote:Is the firmware also separated in files (bootloader/OS/Prime)

The HPPrime_OS.img file, which I started analyzing in that topic (but I should really be moving the information to the TI-Planet hpwiki... and also, I should have written the analysis in English from the get go !) contains separate files for the bootloader and the Prime OS. The "files.sig" file contains validation information for 79 files.
I haven't yet written a program to parse the HPPrime_OS.img file format. In earlier years, I'd have written it in C-like C++, but nowadays, I also need to learn Go, so I'd probably make it in that language, despite the inefficiency of that approach for such small programs - building statically linked, near-empty programs with the standard toolchain seems to yield ~ 1 MB binaries, even after stripping.

Quote:and it only checks signature on the Prime or it's completely locked down?

It validates basically all files, though I haven't checked using the yet-unwritten program that all of the blocks visible in the file are covered by the validation.
I don't yet know precisely how files are validated. ~35 bytes per file rules out a per-file RSA, or probably ECDSA, signature. However, as I wrote in the TI-Planet topic, there might be 32-byte hashes and a 2048-bit RSA key (or two 1024-bit RSA keys) - the numbers are aligned. Of course, it's just a guess at this point, which may be disproved...
I looked for (direct) references to "files.sig" in the whole HPPrime_OS.img file, and listed them in the TI-Planet topic: there are few of them, and one of them is probably related to the block which parses this file and validates the OS contents.