FBI promises to help local law enforcement authorities crack encrypted devices. Letter refers to success in accessing data on an iPhone 5c running iOS 9 that was used by one of the San Bernardino terrorists. Agency did not explicitly promise investigators that it would deploy the same tool, said to have been developed by an outside organization, on other iPhones. FBI had earlier demanded in court that Apple should assist in its attempts to crack by brute force the passcode of the iPhone used by the terrorist, without triggering an auto-erase feature that could be activated after 10 unsuccessful tries.”]