May 29, 2017

DRM for Chargers: Possibly Good for Users

Apple has filed a patent application on a technology for tethering rechargeable devices (like iPods) to particular chargers. The idea is that the device will only allow its batteries to be recharged if it is connected to an authorized charger.

Whether this is good for consumers depends on how a device comes to be authorized. If “authorized” just means “sold or licensed by Apple” then consumers won’t benefit – the only effect will be to give Apple control of the aftermarket for replacement chargers.

But if the iPod’s owner decides which chargers are authorized, then this might be a useful anti-theft measure – there’s little point in stealing an iPod if you won’t be able to recharge it.

How might this work? One possibility is that when the device is plugged in to a charger it hasn’t seen before, it makes a noise and prompts the user to enter a password on the iPod’s screen. If the correct password is entered, the device will allow itself to be recharged by that charger in the future. The device will become associated with a group of chargers over time.

Another possibility, mentioned in the patent, is that there could be a central registry of stolen iPods. When you synched your iPod with your computer, the computer would get a digitally signed statement from the registry, saying that your iPod was not listed as stolen. The computer would pass that signed statement on to the iPod. If the iPod went too long without seeing such a statement, it would demand that the user do a synch, or enter a password, before it would allow itself to be recharged.

How can we tell whether a DRM scheme like this is good for users. One sure-fire test is whether the user has the option of turning the scheme off. You don’t want a thief to be able to disable the scheme on a stolen iPod, but it’s safe to let the user disable the anti-theft feature the first time she syncs her new iPod, or later by entering a password.

We don’t know yet whether Apple will do this. But reading the patent, it looks to me like Apple has thought carefully about the legitimate anti-theft uses of this technology. That’s a good sign.


  1. I’m not sure why you’re attaching this to the DRM moniker.

  2. I can see why it is labeled DRM.

    Unauthorised use can mean use by an unauthorised person. (i.e. a stolen device becomes disabled when someone other than the authorised owner uses it).

    But unauthorised use can also mean use for an unauthorised purpose, by the legitimate owner.

  3. How does this introduce any advantages that software-based locks — such as those commonly available on cell phones — do not? You’d have to implement that sort of functionality anyway, since determining whether a battery is secured by whether it has a charge isn’t reliable. One can easily imagine stolen devices taken to a chop shop where the 5V rail of the connector is rewired into a resistor leading straight into the battery, bypassing the DRM circuitry. This would be dangerous for the next owner, but not much more difficult than replacing an iPod battery. So no: the security needs to surround the use of the charge, not whether charge is allowed into the battery. The latter is too easily circumvented.

    Besides, such a system would mean that for a battery to be charged it would have to be attached to an interface. For many Apple products this is already the case. But other companies offer the convenience of easily interchangeable batteries. It would be inconvenient if this DRM technique spread to those lines.

    Charging is the wrong location for this functionality. Retreating from open standards is a bad idea in general; it happens that this would also be a bad design decision. We should be pursuing a standardized charging regime, both for energy efficiency and interoperability reasons. Allowing companies to retreat into customized, DRM-laden charging solutions is exactly the wrong idea.

    I suspect Apple is pursuing the idea in order to minimize liability and reduce AppleCare claims related to poor-quality third party chargers. I can’t say I blame them for that impulse, but I still don’t think DRM is the answer.

  4. I see this as being analogous to the “kill switch” chips in some inkjet printer cartridges — Apple makes a killing on its accessories and on licensing “official” endorsement of 3rd parties, but then some Taiwanese outfit comes in and sells a very similar product (with perhaps somewhat lower build quality) for a quarter the price, and they want to cut out the competition. I think the “DRM” label is appropriate, because both are used as bludgeons to engage in anti-competitive practices. Apple would like nothing more than to enforce collection of its licensing fees on all accessories, just like Nintendo used to do with NES lockout chips. I *could* see this being used to protect consumers, but as Tom points out, a simple lock code like a cell phone has would be about as effective at theft deterrence.

  5. The Physicist says:

    Apple is a bit too late. Nature was first. For my apple ipod charger I the right combination of metal wires. Copper and zinc work fine. Unauthorized combinations do not work (naturally DRM locked). After the apple charger charged the apple ipod, you may it the apple. BTW, there are better choices than an apple. Even a lemon beats the apple.

  6. The problem with making something like this good for consumers seems to be like the problem in making any other DRM good for consumers. You need some kind of straightforward override in the case of hardware, software or wetware failure, but that override has to be inaccessible to people who would use it to legitimize lost or stolen ipods. (Oh, and the entire process has to be immune to denial-of-service attacks so that someone else can’t declare your ipod stolen and make it stop working.)

  7. I thought of this idea years ago – I should have got in first with the patent shouldn’t I?
    Bear in mind that the thing you call the “charger” is actually just a dumb power supply – the intelligent part is ALWAYS built into the phone. It has to be this way because with LI batteries you must manage discharge as well as charge. So the “DRM” is being applied to the power input – rather than the charger as such. Unfortunately if this is to be effective there really can be no way of switching it off in the phone – or even enabling the phone to “sync” itself to the charger. The best way is to supply a third device (key) with the phone – which can then be used to enable any number of chargers. That way the phone never has enough information on its own to break the system.

    Also this system is analogous to supplying a lock with a key and should not worry most people – since if you have the key you have total control.

  8. Physicist: funny comment, but I wouldn’t eat that apple when you’re done with it if I were you — there are going to be a lot of metal ions in it from your homemade battery.

  9. It’s technology clearly not inspired primarily for anit-theft purposes.
    Perhaps the ant-theft angle is contrived to establish some legitimate useage and deflect the abuse of DMCA arguament.

  10. Nathan Williams says:

    Motorola has already used the technique of “authorized chargers“, and in the bad way, not the good way. Arguably, because it uses a standard (USB) connector for power with this scheme, it’s even worse, since it goes against a broader concept than just the phone-charger pairing.

    (we have one of these phones in my household as well, and it is indeed picky about its source of power-over-USB).

  11. Apple has a long history of locking people into their own products. DO you honestly believe this is any different?

    If my ipod requires an Apple charger sold for 3 times the price of the one i have, i will no longer require an ipod.

  12. Stuart Lynne says:

    Charger – What charger?

    I suppose there was a charger with my (several) iPod’s, but I havn’t seen them since I bought them. All charging is done when plugged into my Windows box via USB…

    But that really makes it simpler to implement. This can be easily implemented in the various drivers by exchanging DRM info after enumeration. If the host does not present the proper authorization then you simply allow the device to operate using Vbus (USB) power. If authorized then you also allow it to charge.

    Actually allowing for a real charger becomes harder, as you then have to actually implement a fair amount of functionality in the charger. Which would make it must more expensive.

    This really does rely on the device having a non-changeable cert being embedded in it. Such that you can only unlock a device (i.e. allow it to charge its battery) IFF you have a network connection and get authorization from Apple (i.e. it’s not on their stolen list.)

  13. @Stuart Lynne: Your iPod actually charges over USB? Mine refuses to do so; it will only take power over FireWire; a fact stated only around the middle of the manual and not anywhere on the box. Given how abundant FireWire connections are on regular PCs, I couldn’t charge and sync at the same time so I had to get a split cable; one end into the PC and the other into the socket adpater (charger).

    Honestly, I can’t see Apple giving consumers the choice here, and their excuse will be something along the line of “confusing the user”, “not elegant”, etc.

  14. Rather than securing the charger, I’m thinking the most direct way to secure the iPod is to put a password on the iPod. It’s a simple programming change and could make the device unusable immediately if stolen rather than giving the thief a few hours of music before running down.

    I would much prefer it if manufacturers would standardize on a single charger platform: one connector that can recharge anything. Any time I have to travel, I have to take a pile of chargers with me for the various electronic gizmos. With a standardized charger, the hotel could supply one like they do with hair dryers now.

    (Yes, it’s true that different devices require different voltage and current profiles for charging, but I believe you could handle that pretty easily by having the device communicate its needs to the charger when you plug it in. And an added bonus is that the charger could be more sophisticated, say complying with Energy Star requirements and international voltage and frequency requirements.)

  15. I saw a clip once of Martha Stewart in the audience of an electronics trade show or something.

    She pulls about a dozen battery chargers out of her purse and asks, “Why do I have to have all of these”?

    I thought that was very effective and right on target.

    I’ve heard that one of the (unspoken) reasons is that manufacturers make most of their profit by selling you yet another battery charger.

  16. Hamster says:

    I like the ruling of the Chinese government, which forced all manufacturers of cellphones to make it possible to charge the devices with an ordinary usb-cable. Hopefully that will apply to other portable devices too.

  17. This is bad.

    Already you can’t buy a 3d party charger for your Power Book because the “MagSafe” connector is patented and not licensed to any 3d parties. Now apple wants to lock your device to an Apple only DRM’d charger and the Prof. thinks that is probably fine? I disagree.

    Apple likes lock in. More lock in==bad for consumers.

  18. sake, it’s because the terrible old ways of pointless competition and messy lack of standards is giving way and the government has finally realized that letting big business always have its way is doubleplusgood.

  19. The Grammarian says:

    “the first time she syncs her new iPod” The impersonal pronoun here should be “his” or even the god-awful politically correct “their” but not “her.” When will people realize that political agendas lead to bad writing?

  20. DRM good? Analogously it would be good for your cough syrup to contain ethylene glycol instead of glycerin, so that if it is stolen from your medicine cabinet, the person who steals it will suffer harm.

  21. Grammarian,

    I disagree. When referring to an abstract person of unknown gender, my practice is to mentally “flip a coin” to pick the person’s gender. Your practice is different. Some readers will prefer my way, others will prefer yours.

    Whether my writing, or yours, is good or bad depends on other factors.

  22. Scott G. says:

    It is interesting to note that the patent was filed over a year and a half ago, in December 2005, so this is obviously something they have been thinking about for some time. It makes you wonder if this is something they expect to actually launch or if they are merely protecting their IP by patenting the idea.

  23. Interloper says:

    Tarkeel, it sounds like you have a pretty old iPod since Apple has not sold iPod cables that are Firewire with iPods in years. Having owned every iPod, I still have some FireWire iPod cables. I use them when I want to charge an iPod from my MacBook Pro, but not sync. When I need to synch, I use a USB cable. If your USB iPod cable wasn’t working, I don’t think it would sync. Perhaps you just don’t understand that your iPod is indeed being charged, though you should be able to tell by the charging icon.

    Physicist, who’s fault will it be when you fry your iPod?

    sake, the fact you don’t know PowerBooks don’t use MagSafe adapters makes me doubt that you have a real gripe. As for the patent, third-party manufacturers may be able to license the technology or come up with their own chargers that don’t rely on the MagSafe slot. Contrary to what you think, Apple is very third-party manufacturer friendly.

    I am doubtful that Apple needs to ride herd on device theft and loss. Consumers just need to be more careful with their devices.

  24. This is tricky, because such a system is only effective in a preventative sense: the average thief is not going to return your iPod when he/she discovers that he/she can’t charge it. Thus, the system only works if the thief can reasonably expect that a substantial fraction of iPods are protected–I only benefit from inconveniencing myself if MOST other iPod owners do the same. If only 1 in 3 iPod owners enable the protection, for example, then 2 out of 3 iPods are still worth stealing.

    So the question becomes: can Apple make this technology easy enough to use that MOST iPod owners will take advantage of it?

  25. Perhaps I’m just cynical but just because they’ve thought about it for the patent application only means that they’re trying to be as creative as possible in order to get the patent.

    Once they have it, they will use it in ways that have the most direct economic benefit to their company which, I fear, will only sometimes overlap with the most consumer friendly ways.

  26. How does this benefit the consumer at all? To believe it does you would have to believe that preventing charging of a stolen ipod is more important than allowing users to charge at whatever charger is convient. Imagine if a charger at work or a friends charger wouldn’t charge your ipod because it could possibly be stolen. Ridiculous. Is ipod theft that common that it has to be discouraged? I think not.

    The obvious answer is that this is a move by apple to create an interface so that peripheral devices must be licensed.

    Also its not DRM, bypassing such a restriction would perfectly legal.

  27. Apart from a couple of completely confused comments (for example, iTunes doesn’t limit the number of copies of a track you can burn at all – it limits the number of copies of a playlist you can burn, and it takes about three clicks to make a new playlist), this protest has completely missed the real villain of the peice. The largest distributor of DRM-infected technology isn’t Apple, it’s not even Microsoft (though they beat Apple on several counts), it’s the movie industry. Every DVD player, every DVD, is infected with DRM. Why aren’t you up in arms over that? Because you don’t notice it? Because it doesn’t effect you?