Schneier on Security

A blog covering security and security technology.

Cyber-Offence is the New Cyber-Defense

This is beyond stupid:

The Pentagon is contemplating an aggressive approach to defending its computer systems that includes preemptive actions such as knocking out parts of an adversary's computer network overseas—but it is still wrestling with how to pursue the strategy legally.

The department is developing a range of weapons capabilities, including tools that would allow "attack and exploitation of adversary information systems" and that can "deceive, deny, disrupt, degrade and destroy" information and information systems, according to Defense Department budget documents.

But officials are reluctant to use the tools until questions of international law and technical feasibility are resolved, and that has proved to be a major challenge for policymakers. Government lawyers and some officials question whether the Pentagon could take such action without violating international law or other countries' sovereignty.

"Some" officials are questioning it. The rest are trying to ignore the issue.

I wrote about this back in 2007.

Posted on September 2, 2010 at 7:33 AM • 16 Comments

Wanted: Skein Hardware Help

As part of NIST's SHA-3 selection process, people have been implementing the candidate hash functions on a variety of hardware and software platforms. Our team has implemented Skein in Intel's 32 nm ASIC process, and got some impressive performance results (presentation and paper). Several other groups have implemented Skein in FPGA and ASIC, and have seen significantly poorer performance. We need help understanding why.

For example, a group led by Brian Baldwin at the Claude Shannon Institute for Discrete Mathematics, Coding and Cryptography implemented all the second-round candidates in FPGA (presentation and paper). Skein performance was terrible, but when they checked their code, they found an error. Their corrected performance comparison (presentation and paper) has Skein performing much better and in the top ten.

We suspect that the adders in all the designs may not be properly optimized, although there may be other performance issues. If we can at least identify (or possibly even fix) the slowdowns in the design, it would be very helpful, both for our understanding and for Skein's hardware profile. Even if we find that the designs are properly optimized, that would also be good to know.

A group at George Mason University led by Kris Gaj implemented all the second-round candidates in FPGA (presentation, paper, and much longer paper). Skein had the worst performance of any of the implementations. We're looking for someone who can help us understand the design, and determine if it can be improved.

Another group, led by Stefan Tillich at University of Bristol, implemented all the candidates in 180 nm custom ASIC (presentation and paper). Here, Skein is one of the worst performers. We're looking for someone who can help us understand what this group did.

Three other groups -- one led by Patrick Schaumont of Virginia Tech (presentation and paper), another led by Shin'ichiro Matsuo at National Institute of Information and Communications Technology in Japan (presentation and paper), and a third led by Luca Henzen at ETH Zurich (paper with appendix, and conference version) -- implemented the SHA-3 candidates. Again, we need help understanding how their Skein performance numbers are so different from ours.

We're looking for people with FPGA and ASIC skills to work with the Skein team. We don't have money to pay anyone; co-authorship on a paper (and a Skein polo shirt) is our primary reward. Please send me e-mail if you're interested.

Posted on September 1, 2010 at 1:17 PM • 20 Comments

More Skein News

Skein is my new hash function. Well, "my" is an overstatement; I'm one of the eight designers. It was submitted to NIST for their SHA-3 competition, and one of the 14 algorithms selected to advance to the second round. Here's the Skein paper; source code is here. The Skein website is here.

Last week was the Second SHA-3 Candidate Conference. Lots of people presented papers on the candidates: cryptanalysis papers, implementation papers, performance comparisons, etc. There were two cryptanalysis papers on Skein. The first was by Kerry McKay and Poorvi L. Vora (presentation and paper). They tried to extend linear cryptanlysis to groups of bits to attack Threefish (the block cipher inside Skein). It was a nice analysis, but it didn't get very far at all.

The second was a fantastic piece of cryptanalysis by Dmitry Khovratovich, Ivica Nikolié, and Christian Rechberger. They used a rotational rebound attack (presentation and paper) to mount a "known-key distinguisher attack" on 57 out of 72 Threefish rounds faster than brute force. It's a new type of attack -- some go so far as to call it an "observation" -- and the community is still trying to figure out what it means. It only works if the attacker can manipulate both the plaintexts and the keys in a structured way. Against 57-round Threefish, it requires 2⁵⁰³ work -- barely better than brute force. And it only distinguishes reduced-round Threefish from a random permutation; it doesn't actually recover any key bits.

Even with the attack, Threefish has a good security margin. Also, the attack doesn't affect Skein. But changing one constant in the algorithm's key schedule makes the attack impossible. NIST has said they're allowing second-round tweaks, so we're going to make the change. It won't affect any performance numbers or obviate any other cryptanalytic results -- but the best attack would be 33 out of 72 rounds.

Our update on Skein, which we presented at the conference, is here. All the other papers and presentations are here. (My 2008 essay on SHA-3 is here, and my 2009 update is here.) The second-round algorithms are: BLAKE, Blue Midnight Wish, CubeHash, ECHO, Fugue, Grøstl, Hamsi, JH, Keccak, Luffa, Shabal, SHAvite-3, SIMD, and Skein. You can find details on all of them, as well as the current state of their cryptanalysis, here. NIST will select approximately five algorithms to go on to the third round by the end of the year.

In other news, we're once again making Skein polo shirts available to the public. Those of you who attended either of the two SHA-3 conferences might have noticed the stylish black Skein polo shirts worn by the Skein team. Anyone who wants one is welcome to buy it, at cost. Details (with photos) are here. All orders must be received before October 1, and we'll have all the shirts made in one batch.

Posted on September 1, 2010 at 6:01 AM • 17 Comments

Eavesdropping on Smart Homes with Distributed Wireless Sensors

"Protecting your daily in-home activity information from a wireless snooping attack," by Vijay Srinivasan, John Stankovic, and Kamin Whitehouse:

Abstract: In this paper, we first present a new privacy leak in residential wireless ubiquitous computing systems, and then we propose guidelines for designing future systems to prevent this problem. We show that we can observe private activities in the home such as cooking, showering, toileting, and sleeping by eavesdropping on the wireless transmissions of sensors in a home, even when all of the transmissions are encrypted. We call this the Fingerprint and Timing-based Snooping (FATS) attack. This attack can already be carried out on millions of homes today, and may become more important as ubiquitous computing environments such as smart homes and assisted living facilities become more prevalent. In this paper, we demonstrate and evaluate the FATS attack on eight different homes containing wireless sensors. We also propose and evaluate a set of privacy preserving design guidelines for future wireless ubiquitous systems and show how these guidelines can be used in a hybrid fashion to prevent against the FATS attack with low implementation costs.

The group was able to infer surprisingly detailed activity information about the residents, including when they were home or away, when they were awake or sleeping, and when they were performing activities such as showering or cooking. They were able to infer all this without any knowledge of the location, semantics, or source identifier of the wireless sensors, while assuming perfect encryption of the data and source identifiers.

Posted on August 31, 2010 at 12:39 PM • 23 Comments

High School Teacher Assigns Movie-Plot Threat Contest Problem

In Australia:

A high school teacher who assigned her class to plan a terrorist attack that would kill as many innocent people as possible had no intent to promote terrorism, the school principal said yesterday.

The Year-10 students at Kalgoorlie-Boulder Community High School were asked to pretend they were terrorists making a political statement by releasing a chemical or biological agent on "an unsuspecting Australian community".

The task included choosing the best time to attack and explaining their choice of victims and what effects the attack would have on a human body.

"Your goal is to kill the MOST innocent civilians," the assignment read.

Principal Terry Martino said he withdrew the assignment for the class on contemporary conflict and terrorism as soon as he heard of it. He said the teacher was "relatively inexperienced" and it was a "well-intentioned but misguided attempt to engage the students".

Sounds like me:

It is in this spirit I announce the (possibly First) Movie-Plot Threat Contest. Entrants are invited to submit the most unlikely, yet still plausible, terrorist attack scenarios they can come up with.

Your goal: cause terror. Make the American people notice. Inflict lasting damage on the U.S. economy. Change the political landscape, or the culture. The more grandiose the goal, the better.

Assume an attacker profile on the order of 9/11: 20 to 30 unskilled people, and about $500,000 with which to buy skills, equipment, etc.

For the record, 1) I have no interest in promoting terrorism -- I'm not even sure how I could promote terrorism without actually engaging in terrorism, 2) I'm pretty experienced, and 3) my movie-plot threat contests are not misguided. You can't understand security defense without also understanding attack.

Australian police are claiming the assignment was illegal, so Australians who enter my movie-plot threat contests should think twice. Also anyone writing a thriller novel about terrorism, perhaps.

An AFP spokeswoman said it was an offence to collect or make documents preparing for or assisting a terrorist attack.

It was also illegal to be "reckless as to whether these documents may assist or prepare for a terrorist attack".

Posted on August 31, 2010 at 6:42 AM • 59 Comments

Misidentification and the Court System

Chilling:

How do most wrongful convictions come about?

The primary cause is mistaken identification. Actually, I wouldn't call it mistaken identification; I'd call it misidentification, because you often find that there was some sort of misconduct by the police. In a lot of cases, the victim initially wasn't so sure. And then the police say, "Oh, no, you got the right guy. In fact, we think he's done two others that we just couldn't get him for." Or: "Yup, that's who we thought it was all along, great call."

It's disturbing that misidentifications still play such a large role in wrongful convictions, given that we've known about the fallibility of eyewitness testimony for over a century.

In terms of empirical studies, that's right. And 30 or 40 years ago, the Supreme Court acknowledged that eyewitness identification is problematic and can lead to wrongful convictions. The trouble is, it instructed lower courts to determine the validity of eyewitness testimony based on a lot of factors that are irrelevant, like the certainty of the witness. But the certainty you express [in court] a year and half later has nothing to do with how certain you felt two days after the event when you picked the photograph out of the array or picked the guy out of the lineup. You become more certain over time; that's just the way the mind works. With the passage of time, your story becomes your reality. You get wedded to your own version.

And the police participate in this. They show the victim the same picture again and again to prepare her for the trial. So at a certain point you're no longer remembering the event; you're just remembering this picture that you keep seeing.

Posted on August 30, 2010 at 12:05 PM • 25 Comments

Security Theater on the Boston T

Since a fatal crash a few years ago, Boston T (their subway) operators have been forbidden from using -- or even having -- cell phones while on the job. Passengers are encouraged to report violators. But sometimes T operators need to use their official radios on the job, and passengers can't tell the difference. The solution: orange tape:

The solution? Goodbye, sober black; hello, bright orange, a hue so vivid that, MBTA officials hope, no one will mistake the radios for phones anymore. Workers at the agency's car barns and garages are in the process of outfitting every handset in the fleet with strips of reflective tape emblazoned with T logos.

[...]

... a small but steady number of hot line tips have been found to be cases of drivers or operators communicating with dispatch by radio, according to video and operations-center call logs.

That is where the electric-orange tape should help, Davey said. Over the past two months, the tape has been applied to handheld radios on about 95 percent of the T's 1,050 buses (each of which has one handset) and one-fourth of its nearly 210 double-ended Green Line trolleys, which have handsets at each end. The rest of the Green Line and the Orange, Blue, and Red line radios will follow.

Taisha O'Bryant, a Roxbury resident who serves as chairwoman of the T Riders Union, said she is more concerned with the frequency and reliability of bus service than the appearance of bus radios. But she said it is a good thing if a driver or operator can call dispatch in the event of a breakdown or service problem without worrying about appearing to talk on a cellphone, and she hailed the cellphone ban.

Of course, no T operator would ever think of putting bright orange tape on his cell phone. Because if he did that, the passengers would immediately know not to report him.

Posted on August 30, 2010 at 5:31 AM • 36 Comments

Friday Squid Blogging: Jewel of the Sea

Pretty.

Posted on August 27, 2010 at 4:28 PM • 7 Comments

Me at the EastWest Institute

Back in May, I attended the EastWest Institute's First Worldwide Cybersecurity Summit in Dallas. I only had eight minutes to speak, and tried to turn the dialog to security, privacy, and the individual.

EDITED TO ADD (9/1): Commentary.

Posted on August 27, 2010 at 12:47 PM • 19 Comments

Is the Whole Country an Airport Security Zone?

Full-body scanners in roving vans:

American Science & Engineering, a company based in Billerica, Massachusetts, has sold U.S. and foreign government agencies more than 500 backscatter x-ray scanners mounted in vans that can be driven past neighboring vehicles to see their contents, Joe Reiss, a vice president of marketing at the company told me in an interview.

This should be no different than the Kyllo case, where the Supreme Court ruled that the police needed a warrant before they can use a thermal sensor on a building to search for marijuana growers.

Held: Where, as here, the Government uses a device that is not in general public use, to explore details of a private home that would previously have been unknowable without physical intrusion, the surveillance is a Fourth Amendment "search," and is presumptively unreasonable without a warrant.

Posted on August 27, 2010 at 7:58 AM • 67 Comments

Detecting Deception in Conference Calls

Research paper: Detecting Deceptive Discussions in Conference Calls, by David F. Larcker and Anastasia A. Zakolyukina.

Abstract: We estimate classification models of deceptive discussions during quarterly earnings conference calls. Using data on subsequent financial restatements (and a set of criteria to identify especially serious accounting problems), we label the Question and Answer section of each call as "truthful" or "deceptive". Our models are developed with the word categories that have been shown by previous psychological and linguistic research to be related to deception. Using conservative statistical tests, we find that the out-of-sample performance of the models that are based on CEO or CFO narratives is significantly better than random by 4% - 6% (with 50% - 65% accuracy) and provides a significant improvement to a model based on discretionary accruals and traditional controls. We find that answers of deceptive executives have more references to general knowledge, fewer non-extreme positive emotions, and fewer references to shareholders value and value creation. In addition, deceptive CEOs use significantly fewer self-references, more third person plural and impersonal pronouns, more extreme positive emotions, fewer extreme negative emotions, and fewer certainty and hesitation words.

Posted on August 26, 2010 at 6:15 AM • 23 Comments

Social Steganography

From danah boyd:

Carmen is engaging in social steganography. She's hiding information in plain sight, creating a message that can be read in one way by those who aren't in the know and read differently by those who are. She's communicating to different audiences simultaneously, relying on specific cultural awareness to provide the right interpretive lens. While she's focused primarily on separating her mother from her friends, her message is also meaningless to broader audiences who have no idea that she had just broken up with her boyfriend.

Posted on August 25, 2010 at 6:20 AM • 46 Comments

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