Handshaking or making ecu accept firmware is one thing, and having completely encrypted firmware with keys stored in "safe" place is another one and second option is unfortunately unsolvable within current public science domain. All your browser data is encrypted and anyone can listen it all day...
That p<>np joke was about ford using ECU with chip implementing some sort of HSM (hardware security module) with encryption for firmware then they will provide you with already encrypted data that can be decrypted only by key locked inside hardware, and all new firmware updates will be encrypted...
Tuned quite some ECUs in the past (edc16, edc17), to my knowledge non of them had been advertised as "locked", it was just checksum algorithm and/or cipher on the data in the ECU storage, and it was always a matter of time when aftermarket was able to keep up with new ECU. However after couple...