I’m not getting the feeling that you actually know what you’re talking about.
This isn’t a discussion about encryption, it’s about pairing modules. Encryption is absolutely necessary and is already used widely across the industry. It might not be transparent (open, published standards), but it’s there.
Illegitimate and low quality parts have always been a concern. You don’t seem like you are a car enthusiast, so go on any car forum or facebook group and ask about some fake wheels or eBay special turbos. You’ll get roasted and start a real stupid discussion on if knockoffs are great for the money or if you’ll die in a fiery wreck. These are simple physical objects which you can fake by casting a mould and pouring something vaguely metallic inside. Fake car electronics can be cheaply remade in a similar fashion. How do you know if a replacement ECU is actually taking in one of the hundreds of datapoints in order to calculate the exact fuel trim to safely use in the millisecond you’re polling? How do you know if your rebuilt or replacement transmission is equipped with the proper logic modules to not cause you to drop into first on the highway, causing you to destroy your engine and probably cause a serious accident?