Hi,
Nothing new here discovery wise, as we know SA2 dates back to 2003.
However, I have implemented SA2 in Python:
https://github.com/bri3d/sa2_seed_keyA quick refresher on SA2: it is the universal seed/key authentication mechanism for flashing pretty much all VAG control units since the early 2000s. ODIS reads an SA2 "script" from either 0x000001bc in an oldschool SGO file or the SECURITY-METHOD=SA2 section of an ODX file. The programming tool then applies the bytecode script against the Seed provided to generate the Key to unlock a Programming session.
While this has been known since the beginning of time pretty much, I still see people trying to reverse the "algorithm" tools are using for various control units. In almost all cases this is completely unnecessary with any SGO/ODX for the same part and this little bytecode runtime. I hope this helps some folks out, cheers!