Google-backed Android devices have a certificate chain where each device has its own certificate, but there's also a root of trust. So you can sign things iden

Google-backed Android devices have a certificate chain where each device has its own certificate, but there's also a root of trust. So you can sign things identifying the specific device, but you can also just verify it was signed by a Google-backed Android device. They might have done something similar. Otherwise, a Sony-wide secret key is still interesting, in some sense, if done competently (which I doubt).