December 2, 2023

Monitoring all the electrical and hydraulic appliances in your house

Dan Wallach recently wrote about his smart electric meter, which keeps track of the second-by-second current draw of his whole house. But what he might like to know is, exactly what appliance is on at what time? How could you measure that?

You might think that one would have to instrument each different circuit at the breaker box, or every individual electric plug at the outlet. This would be expensive, not particularly for all the little sensors but for the labor of an electrician to install everything.

Recent “gee whiz” research by Professor Shwetak Patel‘s group at the University of Washington provides a really elegant solution. Every appliance you own–your refrigerator, your flat-screen TV, your toaster–has a different “electrical noise signature” that it draws from the wires in your house. When you turn it on, this signal is (inadvertently) sent through the electric wires to the circuit-breaker box. It’s not necessary (as one commenter suggested) to buy “smart appliances” that send purpose-designed on-off signals; your “dumb” appliances already send their own noise signatures.

Patel’s group built a device that you plug in to an electrical outlet, which figures out when your appliances are turning on and off. The device is equipped with a database of common signatures (it can tell one brand of TV from another!) and with machine-learning algorithms that figure out the unique characteristics of your particular devices (if you have two “identical” Toshiba TVs, it can tell them apart!). Patel’s device could be an extremely useful “green technology” to help consumers painlessly reduce their electricity consumption.

Patel can do the same trick on your water pipes. Each toilet flush or shower faucet naturally sends a different acoustic pressure signal, and a single sensor can monitor all your devices.

Of course, in addition to the “green” advantages of this technology, there are privacy implications. Even without your consent, the electric company and the water company are permitted to continuously measure your use of electricity and water; taken to the extreme, this monitoring alone could tell them exactly when you use each and every device in your house.

Unpeeling the mystique of tamper-indicating seals

As computer scientists have studied the trustworthiness of different voting technologies over the past decade, we notice that “security seals” are often used by election officials. It’s natural to wonder whether they really provide any real security, or whether they are just for show. When Professor Avi Rubin volunteered as an election judge (Marylandese for pollworker) in 2006, one of his observations that I found most striking was this:

Avi Rubin

“For example, I carefully studied the tamper tape that is used to guard the memory cards. In light of Hursti’s report, the security of the memory cards is critical. Well, I am 100% convinced that if the tamper tape had been peeled off and put back on, nobody except a very well trained professional would notice it. The tamper tape has a tiny version of the word “void” appear inside it after it has been removed and replaced, but it is very subtle. In fact, a couple of times, due to issues we had with the machines, the chief judge removed the tamper tape and then put it back. One time, it was to reboot a machine that was hanging when a voter was trying to vote. I looked at the tamper tape that was replaced and couldn’t tell the difference, and then it occurred to me that instead of rebooting, someone could mess with the memory card and replace the tape, and we wouldn’t have noticed. I asked if I could play with the tamper tape a bit, and they let me handle it. I believe I can now, with great effort and concentration, tell the difference between one that has been peeled off and one that has not. But, I did not see the judges using that kind of care every time they opened and closed them. As far as I’m concerned, the tamper tape does very little in the way of actual security, and that will be the case as long as it is used by lay poll workers, as opposed to CIA

Avi is a first-rate expert in the field of computer security, in part because he’s a good experimentalist—as in, “I asked if I could play with the tamper tape.” To the nonexpert,
security seals have a mystique: there’s this device there, perhaps a special tape or perhaps a thing that looks like a little blue plastic padlock. Most of us encounter these devices in a context where we can’t “play with” them, because that would be breaking the rules: on voting machines, on our electric meter, or whatever. Since we don’t play with them, we can’t tell whether they are secure, and the mystique endures. As soon
as Avi played with one, he discovered that it’s not all that secure.

In fact, we have a word for a piece of tape that only gives the appearance of working:

band-aid: (2) a temporary way of dealing with a problem that will not really solve it (Macmillan Dictionary)

In the last couple of years I’ve been studying security seals on voting machines in New Jersey. For many decades New Jersey law has required that each voting machine be “sealed with a numbered seal”, just after it is prepared for each election (NJSA 19:48-6). Unfortunately it’s hard for legislators to write into the statutes exactly how well these seals must work. Are tamper-indicating seals used in elections really secure? I’ll address that question in my next few articles.

NJ court permits release of post-trial briefs in voting case

In 2009 the Superior Court of New Jersey, Law Division, held a trial on the legality of using paperless direct-recording electronic (DRE) voting machines. Plaintiffs in the suit argued that because it’s so easy to replace the software in a DRE with fraudulent software that cheats in elections, DRE voting systems do not guarantee the substantive right to vote (and to have one’s vote counted) required by the New Jersey constitution and New Jersey statutory law.

I described this trial in three articles last year: trial update, summary of plaintiffs’ witnesses’ testimony, and summary of defense witnesses’ testimony.

Normally in a lawsuit, the courtroom is open. The public can attend all legal proceedings. Additionally, plaintiffs are permitted to explain their case to the public by releasing their post-trial briefs (“proposed findings of fact” and “proposed conclusions of law”). But in this suit the Attorney General of New Jersey, representing the defendants in this case, argued that the courtroom be closed for parts of the proceedings, and asked the Court to keep all post-trial documents from the public, indefinitely.

More than a year after the trial ended, the Court finally held a hearing to determine whether post-trial documents should be kept from the public. The Attorney General’s office failed to even articulate a legal argument for keeping the briefs secret.

So, according to a Court Order of October 15, 2010, counsel for the plaintiffs (Professor Penny Venetis of Rutgers Law School aided by litigators from Patton Boggs LLP) are now free to show you the details of their legal argument.

The briefs are available here:
Plaintiffs’ Proposed Findings of Fact
Plaintiffs’ Proposed Conclusions of Law

I am now free to tell you all sorts of interesting things about my hands-on experiences with (supposedly) tamper-evident security seals. I published some preliminary findings in 2008. Over the next few weeks I’ll post a series of articles about the limitations of tamper-evident seals in securing elections.

Court permits release of unredacted report on AVC Advantage

In the summer of 2008 I led a team of computer scientists in examining the hardware and software of the Sequoia AVC Advantage voting machine. I did this as a pro-bono expert witness for the Plaintiffs in the New Jersey voting-machine lawsuit. We were subject to a Protective Order that, in essence, permitted publication of our findings but prohibited us from revealing any of Sequoia’s trade secrets.

At the end of August 2008, I delivered my expert report to the court, and prepared it for public release as a technical report with the rest of my team as coauthors. Before we could release that report, Sequoia intervened with the Court, claiming that we were revealing trade secrets. We had been very careful not to reveal trade secrets, so we disputed Sequoia’s claim. In October 2008 the Court ruled mostly in our favor on this issue, permitting us to release the report with some redactions,and reserving a decision on those redacted sections until later.

The hearing on those sections has finally arrived, completely vindicating our claim that the original report was within the parameters of the Protective Order. On October 5, 2010 Judge Linda Feinberg signed an order permitting me to release the original, unredacted expert report, which is now available here.

If you’re curious, you can look at paragraphs 19.8, 19.9, 21.3, and 21.5, as well as Appendices B through G, all of which were blacked out in our previously released report.

Did a denial-of-service attack cause the flash crash? Probably not.

Last June I wrote about an analysis from claiming that a kind of spam called “quote stuffing” on the NYSE network may have caused the “flash crash” of shares on the New York Stock Exchange, May 6, 2010. I wrote that this claim was “interesting if true, and interesting anyway”.

It turns out that “A Single Sale Worth $4.1 Billion Led to the ‘Flash Crash’“, according to a report by the SEC and the CFTC.

The SEC’s report says that no, quote-stuffing did not cause the crash. The report says,

It has been hypothesized that these delays are due to a manipulative practice called “quote-stuffing” in which high volumes of quotes are purposely sent to exchanges in order to create data delays that would afford the firm sending these quotes a trading advantage.

Our investigation to date reveals that the largest and most erratic price moves observed on May 6 were caused by withdrawals of liquidity and the subsequent execution of trades at stub quotes. We have interviewed many of the participants who withdrew their liquidity, including those who were party to significant numbers of buys and sells that occurred at stub quote prices. …[E]ach market participant had many and varied reasons for its specific actions and decisions on May 6. … [T]he evidence does not support the hypothesis that delays in the CTS and CQS feeds triggered or otherwise caused the extreme volatility in security prices observed that day.

Nevertheless … the SEC staff will be working with the market centers in exploring their members’ trading practices to identify any unintentional or potentially abusive or manipulative conduct that may cause such system delays that inhibit the ability of market participants to engage in a fair and orderly process of price discovery.

Given this evidence, I guess we can simplify “interesting if true, and interesting anyway” to just “interesting anyway”.