Editor's note: Bruce Schneier is a security technologist and the chief technology officer of Co3 Systems. The opinions expressed in this commentary are solely those of the author.

(CNN) -- Last week Apple announced that it is closing a serious security vulnerability in the iPhone. It used to be that the phone's encryption only protected a small amount of the data, and Apple had the ability to bypass security on the rest of it.

From now on, all the phone's data is protected. It can no longer be accessed by criminals, governments, or rogue employees. Access to it can no longer be demanded by totalitarian governments. A user's iPhone data is now more secure.

To hear U.S. law enforcement respond, you'd think Apple's move heralded an unstoppable crime wave. See, the FBI had been using that vulnerability to get into peoples' iPhones. In the words of cyberlaw professor Orin Kerr, "How is the public interest served by a policy that only thwarts lawful search warrants?"

Ah, but that's the thing: You can't build a "back door" that only the good guys can walk through. Encryption protects against cybercriminals, industrial competitors, the Chinese secret police and the FBI. You're either vulnerable to eavesdropping by any of them, or you're secure from eavesdropping from all of them.

Back-door access built for the good guys is routinely used by the bad guys. In 2005, some unknown group surreptitiously used the lawful-intercept capabilities built into the Greek cell phone system. The same thing happened in Italy in 2006.

In 2010, Chinese hackers subverted an intercept system Google had put into Gmail to comply with U.S. government surveillance requests. Back doors in our cell phone system are currently being exploited by the FBI and unknown others.

This doesn't stop the FBI and Justice Department from pumping up the fear. Attorney General Eric Holder threatened us with kidnappers and sexual predators.

The former head of the FBI's criminal investigative division went even further, conjuring up kidnappers who are also sexual predators. And, of course, terrorists.

FBI Director James Comey claimed that Apple's move allows people to place themselves beyond the law" and also invoked that now overworked "child kidnapper." John J. Escalante, chief of detectives for the Chicago police department now holds the title of most hysterical: "Apple will become the phone of choice for the pedophile."

It's all bluster. Of the 3,576 major offenses for which warrants were granted for communications interception in 2013, exactly one involved kidnapping. And, more importantly, there's no evidence that encryption hampers criminal investigations in any serious way. In 2013, encryption foiled the police nine times, up from four in 2012 -- and the investigations proceeded in some other way.

This is why the FBI's scare stories tend to wither after public scrutiny. A former FBI assistant director wrote about a kidnapped man who would never have been found without the ability of the FBI to decrypt an iPhone, only to retract the point hours later because it wasn't true.

We've seen this game before. During the crypto wars of the 1990s, FBI Director Louis Freeh and others would repeatedly use the example of mobster John Gotti to illustrate why the ability to tap telephones was so vital. But the Gotti evidence was collected using a room bug, not a telephone tap. And those same scary criminal tropes were trotted out then, too. Back then we called them the Four Horsemen of the Infocalypse: pedophiles, kidnappers, drug dealers, and terrorists. Nothing has changed.

Strong encryption has been around for years. Both Apple's FileVault and Microsoft's BitLocker encrypt the data on computer hard drives. PGP encrypts email. Off-the-Record encrypts chat sessions. HTTPS Everywhere encrypts your browsing. Android phones already come with encryption built-in. There are literally thousands of encryption products without back doors for sale, and some have been around for decades. Even if the U.S. bans the stuff, foreign companies will corner the market because many of us have legitimate needs for security.

Law enforcement has been complaining about "going dark" for decades now. In the 1990s, they convinced Congress to pass a law requiring phone companies to ensure that phone calls would remain tappable even as they became digital. They tried and failed to ban strong encryption and mandate back doors for their use. The FBI tried and failed again to ban strong encryption in 2010. Now, in the post-Snowden era, they're about to try again.

We need to fight this. Strong encryption protects us from a panoply of threats. It protects us from hackers and criminals. It protects our businesses from competitors and foreign spies. It protects people in totalitarian governments from arrest and detention. This isn't just me talking: The FBI also recommends you encrypt your data for security.

As for law enforcement? The recent decades have given them an unprecedented ability to put us under surveillance and access our data. Our cell phones provide them with a detailed history of our movements. Our call records, email history, buddy lists, and Facebook pages tell them who we associate with. The hundreds of companies that track us on the Internet tell them what we're thinking about. Ubiquitous cameras capture our faces everywhere. And most of us back up our iPhone data on iCloud, which the FBI can still get a warrant for. It truly is the golden age of surveillance.

After considering the issue, Orin Kerr rethought his position, looking at this in terms of a technological-legal trade-off. I think he's right.

Given everything that has made it easier for governments and others to intrude on our private lives, we need both technological security and legal restrictions to restore the traditional balance between government access and our security/privacy. More companies should follow Apple's lead and make encryption the easy-to-use default. And let's wait for some actual evidence of harm before we acquiesce to police demands for reduced security.

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