Thanks for the research! If they're signing the ECID using an interactive signature algorithm, then it sounds like they've thought it through pretty well. > A

Thanks for the research! If they're signing the ECID using an interactive signature algorithm, then it sounds like they've thought it through pretty well. > And I think the IMEI is more commonly used to identify the radio, not the device itself. Across manufactures, I'm not sure another quasi-unique identifier in common use. > Every time you update an iPhone it generates a nonce, called APTicket. Apple signs that, your ECID and the firmware. This is one variant of interactive signature scheme.