Encryption

Another Salvo in the Second Crypto War (of Words)

By Bruce Schneier
Wednesday, August 12, 2015, 2:02 PM

Prosecutors from New York, London, Paris, and Madrid wrote an op-ed in yesterday's New York Times in favor of backdoors in cell phone encryption. There are a number of flaws in their argument, ranging from how easy it is to get data off an encrypted phone to the dangers of designing a backdoor in the first place, but all of that has been said before. And since anecdote can be more persuasive than data, the op-ed started with one:

In June, a father of six was shot dead on a Monday afternoon in Evanston, Ill., a suburb 10 miles north of Chicago. The Evanston police believe that the victim, Ray C. Owens, had also been robbed. There were no witnesses to his killing, and no surveillance footage either.

With a killer on the loose and few leads at their disposal, investigators in Cook County, which includes Evanston, were encouraged when they found two smartphones alongside the body of the deceased: an iPhone 6 running on Apple’s iOS 8 operating system, and a Samsung Galaxy S6 Edge running on Google’s Android operating system. Both devices were passcode protected.

You can guess the rest. A judge issued a warrant, but neither Apple nor Google could unlock the phones. "The homicide remains unsolved. The killer remains at large."

The Intercept researched the example, and it seems to be real. The phones belonged to the victim, and...

According to Commander Joseph Dugan of the Evanston Police Department, investigators were able to obtain records of the calls to and from the phones, but those records did not prove useful. By contrast, interviews with people who knew Owens suggested that he communicated mainly through text messages — the kind that travel as encrypted data — and had made plans to meet someone shortly before he was shot.

The information on his phone was not backed up automatically on Apple’s servers — apparently because he didn’t use Wi-Fi, which backups require.

[...]

But Dugan also wasn’t as quick to lay the blame solely on the encrypted phones. “I don’t know if getting in there, getting the information, would solve the case,” he said, “but it definitely would give us more investigative leads to follow up on.”

This is the first actual example I've seen illustrating the value of a backdoor. Unlike the increasingly common example of an ISIL handler abroad communicating securely with a radicalized person in the US, it's an example where a backdoor might have helped. I say "might have," because the Galaxy S6 is not encrypted by default, which means the victim deliberately turned the encryption on. If the native smartphone encryption had been backdoored, we don't know if the victim would have turned it on nevertheless, or if he would have employed a different, non-backdoored, app.

The authors' other examples are much sloppier:

Between October and June, 74 iPhones running the iOS 8 operating system could not be accessed by investigators for the Manhattan district attorney’s office — despite judicial warrants to search the devices. The investigations that were disrupted include the attempted murder of three individuals, the repeated sexual abuse of a child, a continuing sex trafficking ring and numerous assaults and robberies.

[...]

In France, smartphone data was vital to the swift investigation of the Charlie Hebdo terrorist attacks in January, and the deadly attack on a gas facility at Saint-Quentin-Fallavier, near Lyon, in June. And on a daily basis, our agencies rely on evidence lawfully retrieved from smartphones to fight sex crimes, child abuse, cybercrime, robberies or homicides.

We've heard that 74 number before. It's over nine months, in an office that handles about 100,000 cases a year: less than 0.1% of the time. Details about those cases would be useful, so we can determine if encryption was just an impediment to investigation, or resulted in a criminal going free. The government needs to do a better job of presenting empirical data to support its case for backdoors. That they're unable to do so suggests very strongly that an empirical analysis wouldn't favor the government's case.

As to the Charlie Hebdo case, it's not clear how much of that vital smartphone data was actual data, and how much of it was unable-to-be-encrypted metadata. I am reminded of the examples that then-FBI-Director Louis Freeh would give during the First Crypto Wars in the 1990s. The big one used to illustrate the dangers of encryption was Mafia boss John Gotti. But the surveillance that convicted him was a room bug, not a wiretap. Given that the examples from FBI Director James Comey's "going dark" speech last year were bogus, skepticism in the face of anecdote seems prudent.

So much of this "going dark" versus the "golden age of surveillance" debate depends on where you start from. Referring to that first Evanston example and the inability to get evidence from the victim's phones, the op-ed authors write: "Until very recently, this situation would not have occurred." That's utter nonsense. From the beginning of time until very recently, this was the only situation that could have occurred. Objects in the vicinity of an event were largely mute about the past. Few things, save for eyewitnesses, could ever reach back in time and produce evidence. Even 15 years ago, the victim's cell phone would have had no evidence on it that couldn't have been obtained elsewhere, and that's if the victim had been carrying a cell phone at all.

For most of human history, surveillance has been expensive. Over the last couple of decades, it has become incredibly cheap and almost ubiquitous. That a few bits and pieces are becoming expensive again isn't a cause for alarm.

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