"It doesn't work," said Director James Comey when asked about the technique, called "NAND mirroring," during a press conference announcing the indictment of seven Iranian nationals on charges of launching cyberattacks against U.S. banks and accessing the computerized control systems of a dam north of New York City.
A reporter asked Comey about speculation that the most probable method of cracking the iPhone would rely on using numerous copies of the iPhone storage to input possible passcodes until the correct one was found.
"I've heard that a lot," Comey replied, then shook his head and added, "It doesn't work. We've had lots of people come forward with lots of ideas, and now we have one."
Comey declined to identify the method or name the company that reached out to the FBI last weekend.
"We tried it on Sunday, and it looked like it might work," Comey said of the technique. "And so we wanted to alert the court immediately."
The reporter and Comey were referring to an abrupt about-turn by the FBI on Monday, when it told a federal magistrate that it had a new lead on how to access the information on the iPhone 5C used by Syed Rizwan Farook, who along with his wife, Tafsheen Malik, killed 14 in San Bernardino, Calif., on Dec. 2, 2015. The two died in a shootout with police later that day. Authorities quickly called it a terrorist attack.
Last month, the Department of Justice (DOJ) obtained a court order that compelled Apple to assist the FBI in getting into Farook's phone. Apple was told that it must write software to circumvent iOS 9's security safeguards so that the FBI could take an unlimited number of passcode guesses in the hope of unlocking the device. Apple has contested the order.
Until Monday, the FBI and the DOJ had repeatedly said in court filings that only Apple was in a position to help.
On Monday, Jonathan Zdziarski, a noted iPhone forensics and security expert, told Computerworld that the most likely scenario for bypassing Apple would be NAND mirroring, which requires desoldering the phone's processor from the circuit board, copying its contents, and writing the data to another chip using a reader/programmer.
With the ability to make an unlimited number of copies from the original data, a forensics firm could try passcodes on one copy until 10 incorrect guesses, at which point iOS blocks further attempts. That copy could then be discarded and a fresh version re-copied onto a chip for another 10-guess run.
On Monday, the DOJ asked the magistrate to cancel a hearing scheduled for the next day, and said it would produce a status update by April 5. Until then, the order mandating Apple's help has been stayed.
Comey also defended his agency against accusations that it had been untruthful when it insisted that only Apple was able to get into Farook's iPhone but then announced a possible alternate avenue just hours before the hearing. The FBI had used the argument that it needed Apple's help as justification for the court order compelling the Cupertino, Calif., company to hack its own software.
"I don't feel defensive. I do feel strongly when someone accuses the Department of Justice or the FBI of being dishonest. That is something that cannot be let to lie, to sit there," said Comey in reply to another reporter's question at the press conference.
Comey implied that, whether or not the unknown partner's technique worked, the FBI and the DOJ would continue to press for easier access to encrypted devices by law enforcement.
"Our goal all along is to facilitate an adult conversation about a serious conflict between two things we all care about. That is our goal, "Comey said. "San Bernardino is about that investigation. Even if this particular technique makes that go away ... we still have to resolve this conflict between these values we care about, and we hope there will be an adult conversation."
The FBI chief was on the offensive about the iPhone debate elsewhere this week.
In a short letter to the editor to the Wall Street Journal (subscription required) Wednesday, Comey denied that his agency's attempt to force Apple to assist was part of a scheme to set a legal precedent which would smooth the way for similar requests down the line.
"The San Bernardino case was not about trying to send a message or set a precedent; it was and is about fully investigating a terrorist attack," Comey wrote in response to an unsigned editorial the newspaper published Tuesday.