So… over the past couple days, plenty of folks (including us) have reported that the backdoor demanded by the FBI (and currently granted by a magistrate judge) would likely work on the older iPhone model in question, the iPhone 5C, but that it would not work on modern iPhones that have Apple‘s „Secure Enclave“ — basically a separate chip that stores the key.
Plenty of reports — including the Robert Graham post that we linked to, and a story by Bruce Schneier — suggested that an attempt to follow through with the FBI‘s request in the presence of the Secure Enclave would effectively eliminate the key and make decryption nearly impossible.