“They must be encrypted with AES-128-CBC using key=")1Zorxo^fAhGlh$#" and IV=“aoAkfwk+#1.6G{dE”.”
Hyundai signs head unit updates with an RSA key nobody has found. It also ships a secret recovery mode, triggered by holding two buttons at startup, that flashes files from a USB drive encrypted with a key hardcoded in the bootloader. The same firmware runs on Hyundai, KIA and Genesis models from 2018 to 2021. The head unit runs Linux 3.1.10. The signature check guards the front door while the recovery mode leaves the garage open.