Gen. Michael Hayden, former CIA director. (AP Photo/Luis M. Alvarez)

McLEAN, VA — Retired four-star general Michael Hayden, who as director of the NSA installed and still defends the controversial surveillance program to collect telephone metadata on millions of Americans, says he opposes proposals to force Apple and other tech companies to install “back doors” in digital devices to help law enforcement.

In an emerging court battle over access to information on the iPhone owned by one of the San Bernardino attackers, Hayden says “the burden of proof is on Apple” to show that limited cooperation with investigators would open the door to broader privacy invasions. Apple is being asked not to decrypt information on the smartphone but rather to override the operating system so investigators could try an endless series of passwords to unlock it.

“In this specific case, I’m trending toward the government, but I’ve got to tell you in general I oppose the government’s effort, personified by FBI Director Jim Comey,” Hayden told Capital Download in an interview about his memoir, Playing to the Edge: American Intelligence in the Age of Terror. “Jim would like a back door available to American law enforcement in all devices globally. And, frankly, I think on balance that actually harms American safety and security, even though it might make Jim’s job a bit easier in some specific circumstances.”

In a statement released late Sunday, Comey said the San Bernardino litigation “isn’t about trying to set a precedent or send any kind of message. It is about the victims and justice. Fourteen people were slaughtered and many more had their lives and bodies ruined. We owe them a thorough and professional investigation under law. That’s what this is. The American people should expect nothing less from the FBI.”

Hayden, 70, brings unparalleled credentials to the roiling debate. The retired Air Force general is the only person ever to head both the super-secret National Security Agency and the Central Intelligence Agency. In his 448-page memoir, published Tuesday by Penguin Press, he recalls being at the NSA on Sept. 11, 2001, when Al Qaeda attacked the World Trade Center and the Pentagon. He led the CIA during firestorms over its detention and interrogation of terror suspects, and while targeted killings by drones grew.

The title of the book — on the jacket, even the words bleed to the edge — refers to his conclusion that intelligence officials should play so close to the line that they get chalk dust on their cleats. “It’s unapologetic,” he says of his account of the decision-making behind drone attacks, the use of waterboarding and other interrogation techniques, the intelligence failures in the lead-up to the invasion of Iraq, and the culture of America’s espionage agencies.

A federal District Court judge in California last week ordered Apple to bypass security barriers on the iPhone5c that had been used by Syed Rizwan Farook, who with his wife killed 14 people at an office holiday party in December. In a defiant public letter, Apple CEO Tim Cook announced the company wouldn’t comply. Apple argues the tool inevitably would be used not just in one isolated case but repeatedly.

The showdown has reinvigorated proposals for Congress to pass a law that would require tech companies including Apple, Facebook and Google to provide a “back door” in digital devices so law-enforcement officials could access encrypted information during investigations. The debate has become an issue in the presidential campaign. Republican frontrunner Donald Trump has called for a boycott of Apple products unless the company cooperates with the San Bernardino investigators.

“Look, I used to run the NSA, OK?” Hayden told USA TODAY’s weekly video newsmaker series. “Back doors are good. Please, please, Lord, put back doors in, because I and a whole bunch of other talented security services around the world — even though that back door was not intended for me — that back door will make it easier for me to do what I want to do, which is to penetrate. …

“But when you step back and look at the whole question of American security and safety writ large, we are a safer, more secure nation without back doors,” he says. With them, “a lot of other people would take advantage of it.”