Elizabeth Weise, and Kevin Johnson

USA TODAY

Law enforcement officials Thursday threw cold water on two recent theories on how the FBI was attempting to hack into an iPhone used by one of the San Bernardino terrorists but wouldn't name the mysterious "outside party" that is trying to help it navigate Apple's built-in passcode encryption.

FBI Director James Comey, in response to a reporter's question at a briefing, said making a copy of the iPhone’s chip in an effort to circumvent the password lockout “doesn’t work.” Comey wouldn't identify the company that's helping it or discuss details of the technique.

A widely discussed scenario in the security world, put forward by a staff technologist at the ACLU, has been that the FBI had found a way to remove crucial chips from the iPhone, make digital copies of them and then run multiple passcode attempts against the digital copies, while keeping the phone's software itself untouched.

That would avoid tripping the self-erase program built into the iPhone, the security hurdle that's at the crux of the U.S. government's legal fight with Apple.

Apple v FBI timeline

Law enforcement officials speaking on background debunked another report that had named Israeli forensics firm Cellebrite as the mystery firm helping it break into the phone.

On Wednesday, the Israeli newspaper Yedioth Ahronoth reported that the company that specializes in extracting information from cellphones was the mysterious "outside party." The FBI had previously bought kits for extracting data from cellphones from Cellebrite.

The officials, who are not authorized to speak publicly on the matter, declined to identify the outside party providing the technical assistance.

FBI flooded with suggested hacks for iPhone

Comey was speaking at a Department of Justice briefing in Washington on Thursday morning with Attorney General Loretta Lynch, New York U.S. Attorney Preet Bharara and John Carlin, assistant attorney general of DOJ’s National Security Division.

On Monday, in a surprise shift in the month-long public dispute between the U.S. government and Apple over whether the iPhone maker should be forced to create a software workaround to its encryption, the DOJ had asked that a hearing on the case scheduled for Tuesday be canceled. It told the court that an unnamed outside party had come forward with a possible solution to getting into the iPhone that wouldn't require Apple's assistance, and that it would update the court by April 5.

Apple v FBI timeline

Thursday's briefing focused on new federal indictments against Iranian hackers charged with cyberattacks that targeted major U.S. banks and financial institutions, along with a dam in Rye, N.Y.

But the officials also fielded questions about this week’s Brussels terror attack and the DOJ legal confrontation with Apple over the iPhone of the San Bernardino shooter.

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Comey said: “We tried everything we could think of, asked everybody inside and outside of government” about possible ways to get the iPhone data before getting into a legal standoff with Apple.

Widespread media publicity about the court battle “has stimulated a marketplace of folks around the world who have ideas” about what techniques might enable the FBI to gain access to the iPhone’s data, Comey said.

“People have come from all over the globe with suggestions,” Comey said.

But, reiterating the DOJ assertion in Monday night’s application for delaying the Apple hearing, Comey said “it’s someone who came forward with an idea” last weekend.

Even if the procedure works with the San Bernardino phone, Comey said the U.S. government, law enforcement officials and technology firms need to come to an agreement about how to handle the broader privacy-vs-security question.

“We still have to, as a country, resolve this conflict,” Comey said.

FBI flooded with suggested hacks for iPhone

Contributing: Kevin McCoy in New York. Follow USA TODAY cybersecurity reporter Elizabeth Weise on Twitter @eweise