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Smart Meters Reveal What You're Watching

Posted by Unknown on from the we're-always-watching dept.

xororand writes "H-Online reports that 'researchers at the Münster University of Applied Sciences have discovered that it is possible to use electricity usage data from smart electricity meters to determine which programmes consumers are watching on a standard TV set. By analysing electricity consumption patterns, it is, in principle, also possible to identify films played from a DVD or other source.' It's time for some clever EEs to come up with a countermeasure. Unfortunately alumfoil hats have already been dismissed."

18 of 170 comments (clear)

  1. Hmmm... by MightyMartian · · Score: 2

    I'm guessing if you built a plugin AC device that just sort of created random draws on your electrical supply, say ten times a minute, for random durations, I imagine that would pretty much kill any leak of such information.

    --
    The world's burning. Moped Jesus spotted on I50. Details at 11.
    1. Re:Hmmm... by MatthiasF · · Score: 3, Informative

      You could also buy a cheap uninterruptable power supply (battery) or line filter (capacitors) for the same effect.

      Unlikely the battery or filter would draw 1 for 1 from the wall and would probably smooth the signal out enough to be indistinguishable.

    2. Re:Hmmm... by MightyMartian · · Score: 2

      That's a good point. A UPS isn't a bad idea for your electronics, and can save you from nasty things like lightning strikes and overloads.

      --
      The world's burning. Moped Jesus spotted on I50. Details at 11.
    3. Re:Hmmm... by fuzzyfuzzyfungus · · Score: 2

      It might well be easier(and possibly even more efficient) to plug the object you don't want leaking data into a proper dual-conversion UPS, tweaked slightly to allow itself to discharge to a random level(somewhere between 50 and 90 percent, say) before starting a charge cycle.

  2. A new DPA application by Andy+Dodd · · Score: 2

    In the cryptography world, this is known as a sidechannel attack - specifically DPA.

    "It's time for some clever EEs to come up with a countermeasure."
    There are plenty of countermeasures for DPA in the crypto world - However:
    1) The negative impact of this is a hell of a lot lower than key extraction
    2) The positive effects of having power consumption tied to scene brightness are significant. Localized backlight dimming means that a scene with low average brightness uses less power. OLED displays take this to another level - black pixels use no power.

    Also - In this case it appears they were only able to identify which channel a TV was tuned into. DVR makes this MUCH more difficult because fast-forward/rewind vastly increases the number of datasets you need to compare against. Also, while in theory you could identify a DVD, the selection of possible DVDs is so great and the amount of noise in the measurements is such that you're never in practice going to be able to identify someone's watched content reliably.

    --
    retrorocket.o not found, launch anyway?
  3. How about... by walkerp1 · · Score: 2

    simultaneously running an identical device with an inverted signal? Now may I please have my daily allotment of tinfoil? Yummy!

  4. Re:Why do it like this when the cable box can repo by LordKronos · · Score: 2

    Well, for starters, I'm assuming the cable company wouldn't want to be sharing its data with the electric company. Second, this is useful for anyone who doesn't have a cablebox. Cablecards installed into a TV, PC, or anything other than a cablebox are inherently one-way devices. The current spec has no mechanism for them to do 2-way communication (unless it's a SDV system that requires a tuning adapter). The same is true for the little DTA devices and QAM tuners.

  5. I fail to see how it would work anyhow by Sycraft-fu · · Score: 2

    They say that "a minimum of interference from other devices". Right, except my electricity meter is for my house, and it has many other devices. So unless you think I'm going to turn off all my lights, my computers, unplug my fridge, shut off my A/C, and so on when I watch a movie, then I can't see this working.

    Also there's the fact that light vs dark really doesn't have much difference in terms of power draw on an LCD. Yes there is a bit used to change the crystals, but not nearly as much as the backlight. Then to that you add maybe a receiver, drawing power to do sound and so on.

    I could see this perhaps working if you had a meter right on the feed to the TV, but on the whole house? Good luck getting useful data when the A/C is running, drawing 30 amps.

  6. Countermeasures by StikyPad · · Score: 2

    Countermeasures already exist. They're called capacitors.

    --
    https://www.eff.org/https-everywhere
  7. Standard TV set by vlm · · Score: 2

    I think the key in the article is "standard TV set" by which they mean a CRT. A CRT varies its HT current draw by scene brightness, and its quite visibly obvious when troubleshooting. Heck even a cheapie consumer grade wattmeter could probably detect it. On /. a CRT is probably not considered a "standard TV" anymore, but out in the real world, deployed CRTs on the ground showing shiney pictures probably still outnumber all other deployed and working technologies, at least for a few more years...

    On the other hand, the florescent backlight in my piece of junk basement LCD TV is constant power draw, no matter if the LCD pixels let light thru or not. The LCD pixels themselves draw about the same no matter scene brightness. Anyone who's ever done anything with embedded systems knows this... the LCD display itself is usually rated around a milliamp, most of which is wasted in the control ckts, and the backlight usually draws a good fraction of an amp. Even allowing for much higher current draw for fast moving scenes and higher contrast, I'm betting the backlight still wins for power draw.

    --
    "Science flies us to the moon. Religion flies us into buildings." - Victor Stenger
  8. What else you could do with a smart meter by prefec2 · · Score: 2

    See when you open your refrigerator, when your heating kicks in even if it is gas driven due to the start pulse. Every electricity consumption can be monitored and it can be interpreted allowing to see when you get up, what your behavior is (at home). That's why we need data security. No company should be allowed to use these data other than to control electricity production.

  9. How this would actually work, and its real limits. by queazocotal · · Score: 2

    This is not as simple as some people think to block. A simple random load added to the mains signal will not do it.
    In order to find out if you're watching a given TV program - first you take the TV program, and measure every 5 second periods average brightness..
    This gives you 720 samples for an hour.
    Now, you load up 720 5 second samples from the targets electricity meter.

    You subtract the average value from each of these, so they're symmetrical about 0.

    Now, you go through the list, multiplying the first brightness by the first measured energy use, and add this to a total. Repeat this 720 times.

    Now, you have the correlation of the power with the TV program.
    This is _MUCH_LARGER_ than the correlation of any single time period, and any noise or random non-correlated signal such as fridges or freezers drops out to a large degree.

    Random signals have to be of the order of sqrt(720) - 36 times larger than the signal to mask it.

    (It's not quite this bad, as there will be some false correlation, epecially given there will be millions of candidate programs, and 5s offsets that can occur)
    And yes, LCDs, especially LCDs with newer variable power 'energy saving' backlights that dim or brighten along with the program content to optimise contrast and power use will work for this just fine.

  10. Re:In Soviet Amerika.. by prefec2 · · Score: 3, Funny

    I thought TV in America is like TV in 1984, but in color and with more channels.

  11. Re:I make these Smart Metering Devices by xororand · · Score: 2

    First you are not going to get second by second readings from your standard L&G or Itron meter. The back haul doesn't have the bandwidth and even if you had a second broadband ESI (energy service interface) in your home there are a few technical hurdles preventing 1 second granularity (2.5 seconds is the fastest that I've seen and not sustained).

    However these meters also report the phase difference between the Voltage and the Current. Using this information you can filter out pool pumps, air conditioners, furnace fan etc. As you learn more about what is on in a persons home it does become easier to figure out how an individual appliance is working.

    There are a large number of privacy concerns that need to be addressed with Smart Metering. We should probably solve them before some companies start using your personal electricity consumption as a revenue stream

    Thanks for the info, AC.
    I wish I had mod points.

  12. Re:Why do it like this when the cable box can repo by marnues · · Score: 2

    To add to the other commenter, cableboxes are mostly one-way devices as well. They keep trying to implement 2-way communications, but even if the box is capable the cable company I work for does not implement this. Video engineers are a dying breed because they don't want to learn about things like 2-way communication and packet switching. I can guarantee that once the network engineers have their way and video is just another packet service, the pipes will be cleaner, your digital feed will be much smoother, and Nielson will be dead as a doorknob.

  13. There's no way this is right by sxltrex · · Score: 3, Informative

    I work for a large utility that is currently implementing an AMI system. I can tell you from first hand knowledge that no utility gets (or wants) usage data from its customers every 2 seconds. At my utility we collect usage in 1 hour bins for residential customers and 15 minute bins for commercial and industrial customers. The amount of database storage we would need to collect 2 second interval data from all of our customers would be staggering. As it is we've had to invest in a large server farm to handle the data we are getting.

    If I had to guess I'd say that the 2 second intervals are for in-home monitoring using a ZigBee HAN, or something similar (the EasyMeter website is in German and does not appear to have much technical info).

  14. Re:Why do it like this when the cable box can repo by networkBoy · · Score: 2

    I was told that I "had to connect my receiver to the phone or internet for correct operation". I said I have kids, I will not honor any PPV purchases. They dropped the issue.

    --
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  15. Not so much. by Sycraft-fu · · Score: 2

    http://en.wikipedia.org/wiki/Smart_meter

    Smart meters just talk to the utility company more often. It is still a single point of reading because that's all they care about. The power company doesn't give a shit what I spend my power on, they just need to know how much so they can charge me for it. Not only would they have trouble getting people to agree to monitors on every outlet, but there's no way they'd want to bear the cost, or the insurance issues. They want a single point of demarcation past which nothing is their problem, and that is the meter. They just want meters that can read automatically, and more often.