Search "How Apple's encryption works" in this text...
http://blog.cryptographyengineering.com/2014/10/why-cant-apple-decrypt-your-iphone.html
The secure enclave enforces a five-second delay between failed PIN requests, it can't return the encryption keys, and they'd have to flash new firmware onto the running device into the first place, without the device's co-operation.
Biting the hand that feeds IT
