[csrm123]

Is there literally no other way that the FBI could get the data off the phone?

I'm sure they could download the memory, stick it all in some kind of iOS VM and try every 4-digit PIN in no time, all without worrying that the phone would self-destruct.

Couldn't they?

[weinzierl]

No. Flash memory is encrypted with a key that is derived not only from the PIN but also an ID that is fused into the device when it is manufactured. If we exclude the possibility of a backdoor there is no way to retrieve this ID expect from the silicon itself.

Encryption keys are stored unencrypted in RAM, but only as long as the device is active. RAM loses it's content quickly when it is not refreshed every few micro seconds. Moreover the RAM in the iPhone is a package on package design which makes it hard to connect to it.