[jordigh]

I wonder if people even know what those restrictions are and how exactly the anti-tivoisation clause works. It does not forbid anyone from running software on tivoised devices, which is what some people seem to think it does. All that it requires is that if you distribute the software primarily to be used on a User Product (as GPLv3 calls it), then as part of the installation information (which in GPLv2 used to just mean install and build scripts), you must also provide the signing keys for the hardware.

This also does not mean that GPLv3 makes software signing impossible and that you must forbid users from rejecting unsigned software if they so wish. It doesn't mean that you have to distribute every secret key that you use for signing software. It merely means that you have to give your users a way to install software on the User Product as they see fit, if they see fit. It's up to the user to decide to override any signing feature or not. It's very much in spirit with GPLv2 that required installation scripts. As far as GPLv3, hardware signing keys are just another part of installation scripts (the actual term used in GPLv3 is "Installation Information").

http://radar.oreilly.com/2007/03/gplv3-user-products-clause....

https://copyleft.org/guide/comprehensive-gpl-guidech10.html#...

[eridius]

Or to put it another way, GPLv3 mandates that your hardware be insecure (because you cannot prevent a malicious actor from installing malicious software on someone's device, which would normally be done by requiring all updates to be codesigned by the manufacturer). And it's not just limited to software that would be installed on the hardware; companies like Apple won't even allow employees to install GPLv3 software on their work computer because if a single piece of GPLv3-licensed code makes it into iOS, even completely accidentally, the license demands that Apple release their root signing keys to the world, completely destroying the security of hundreds of millions of devices.

Also don't forget the patent stuff in GPLv3. That's not quite as scary as the anti-TiVoization stuff, but it's still pretty significant for large companies.

[gherkin0]

> GPLv3 mandates that your hardware be insecure (because you cannot prevent a malicious actor from installing malicious software on someone's device, which would normally be done by requiring all updates to be codesigned by the manufacturer).

I think that's wrong: http://www.gnu.org/licenses/gpl-faq.en.html#GiveUpKeys:

> I use public key cryptography to sign my code to assure its authenticity. Is it true that GPLv3 forces me to release my private signing keys? (#GiveUpKeys)

> No. The only time you would be required to release signing keys is if you conveyed GPLed software inside a User Product, and its hardware checked the software for a valid cryptographic signature before it would function. In that specific case, you would be required to provide anyone who owned the device, on demand, with the key to sign and install modified software on his device so that it will run. If each instance of the device uses a different key, then you need only give each purchaser the key for his instance.

It sounds like a manufacturer could ship a GPLv3-compliant User Product with two signing keys: a secret one known only to the manufacturer, and a second per-device key than can be used by the end-user to install modified software. Such a manufacturer wouldn't be forced to disclose their signing key because the user already has access to an equivalent.

I also imagine it would be kosher for the device to provide the user the option, in the name of security, to permanently clear the second per-device key, so only manufacturer updates can ever be installed.

> companies like Apple won't even allow employees to install GPLv3 software on their work computer because if a single piece of GPLv3-licensed code makes it into iOS, even completely accidentally, the license demands that Apple release their root signing keys to the world, completely destroying the security of hundreds of millions of devices.

If Apple is behaving that way, it's Apple's own fault, not the GPLv3's. They could have chosen to design their software in a way that would have given them better options if they are ever forced to comply with the GPLv3, but they chose not to.

[eridius]

What you've just described is a completely insecure hardware platform. Giving out a second private key that can still be used to install third-party updates is just as insecure as giving out their normal private key, the only real difference is if anyone actually looks at the code signature they can tell the difference between third-party and first-party code. Allowing the user to lock out that second key doesn't fix anything because 99.99% of users will never do that, or even know it exists.

> If Apple is behaving that way, it's Apple's own fault, not the GPLv3's. They could have chosen to design their software in a way that would have given them better options if they are ever forced to comply with the GPLv3, but they chose not to.

That makes no sense. What you said is basically equivalent to "That's Apple's fault, they could have just designed their hardware platform to be completely insecure".

GPLv3 is fundamentally incompatible with having a secure hardware platform. This is absolutely GPLv3's fault.

[dTal]

>GPLv3 is fundamentally incompatible with having a secure hardware platform

That's funny because Chromebooks ship with GPLv3 code.

[eridius]

I'm not familiar with the security model of Chromebooks. How does it work?

[dTal]

Out of the box, they only accept Google OS updates. For reference, the OS is basically Gentoo+Chrome.

If you've a mind to, you can put the Chromebook in "developer mode" with a magic sequence of commands (requiring physical access as it's a boot procedure). This gives you root. To protect naive users from being exploited, a Chromebook in developer mode will display a nasty warning on boot. This warning lingers on the screen for an annoying amount of time, accompanied by a beep. The only way (and it's undocumented) of skipping the wait and the beep is with Ctrl-D; pressing any other key while on this screen results in the Chromebook being completely reset. All this is to ensure that it's virtually impossible to run under developer mode unintentionally.

If all this gets too annoying and you want to use the Chromebook as a fully general device, you can blow it away by replacing the bootloader. Doing this requires disabling write-protection on the flash, which requires opening the case.

Disclaimer: I own a Samsung ARM Chromebook. For all I know the precise details may vary across the Chromebook line, though I believe they all work similarly. Fuller details are here: https://www.chromium.org/chromium-os/developer-information-f...

[gherkin0]

> Allowing the user to lock out that second key doesn't fix anything because 99.99% of users will never do that, or even know it exists.

That's easily solved: On initial device setup, the user could be asked to explicitly disable the key by asking something like "Would you like to secure your device by permanently disallowing the installation of untrusted software? Y/N"

Also, as someone else clarified below, the alternate key I was proposing is unique to the device. So any attack against you would have to be tailored to your device. That leaves the main threats as: 1) an NSA-like shipment-interception and 2) someone getting access to your user key after the device is in your possession. 1) can be mitigated by buying your device in a random retail shop, and 2) can be prevented by immediately permanently clearing the user the key.

[dTal]

Now you have a number of thorny design decisions.

For example, can the user change their own key? If yes, the device can never be trusted second-hand - the OS might have been modified to secretly accept more keys. If no, then the device also can never be trusted second-hand - the previous owner could well have retained the key. And which key is superior, the manufacturer key or the user key? Can the possessor of a key override actions attempted using the other key?

Also, as written, this is just a bad solution. So you ask the user on initial setup. Let's say 99% of users won't know what the question is asking. So maybe they hit "yes", and now we're just back to iPhones and no user freedom, for them or any subsequent device owners. Or maybe they hit "no", and now they're no more secure and there was really no point in asking them. Maybe it's a 50-50 split, depending on how they feel (and not related to how they would choose given informed consent). Or maybe the user is informed, in which case they are very likely to just hit "no", if for no other reason than to preserve the resale value.

Don't get me wrong, I do think this could be done right. But attempting to guarantee "security" (that is, the dubious sort of security that is manufacturer-only updates) to naive users, freedom to power users, and preserve those guarantees as the device changes hands... well, that's a Hard Problem. I think only Chromebooks have attempted it so far.

[gherkin0]

> If yes, the device can never be trusted second-hand - the OS might have been modified to secretly accept more keys.

That's always going to be a risk with second-hand devices (or even new devices). Who knows what kind sneaky things someone did to a device that they had long-term access to. You can never really totally trust something that you didn't build yourself from the ground up, so you always have to accept some level of risk.

That UI solution was just a random idea, I'm sure there are better ones. Like you said, it's a Hard Problem.

[malka]

Each user would get its own private key that could only be used on its own device. It could not be used to sign software for someone else device

[eridius]

Hmm, that's actually the first suggestion I've heard that's at least technically workable, though it's pretty darn impractical to do at any kind of scale.

[gherkin0]

> though it's pretty darn impractical to do at any kind of scale.

How so? It's a solved problem. Don't smartphones already have numerous device-specific identifiers and keys loaded to them? All they would really need to do is slap an extra sticker on the device with the device-specific key printed on it. For instance, my phone came with a sticker with its IMEI printed on it.

[dTal]

As I mentioned in another comment in this thread, it is already done for randomized administrator and wifi passwords in consumer routers.

[jordigh]

Actually, I think Apple is already more or less compliant with this part of GPLv3, as they allow developers to self-sign the software, right? You just have to pay for a self-signing key. That's sufficient, because it means you can run modified software. All they have to do is lift the restriction to pay for the self-signing key.

[eridius]

I'm talking about the OS here. But the App Store is also incompatible with GPLv3 and GPLv2 for other reasons.

[dTal]

Is there a problem with, say, printing the key on the device case, as is done with administrator passwords for consumer routers? Or, if you're worried about casual skimming, inside the case? Under a tamper seal if it makes you feel better? You're basically at the Chromebook security model by that point, which seems well-regarded around here.

It's pointless anyway trying to "secure" hardware against a sufficiently determined attacker with physical access. There's an argument to be made that physical access should equal software ownership, philosophically.

It's also worth noting that requiring all updates to be signed by the manufacturer does not protect you from malicious code, as manufacturer updates can also be malicious. Ultimately, the "owner" of the device should be at the top of the pyramid of trust.

[eridius]

Physical access should not equal ownership. Haven't you been paying attention at all to the Apple vs FBI case? Apple works very hard to keep devices secure even when they're in the possession of someone else. Obviously in this particular case a third-party firm was able to crack the iPhone (though without saying how), but you can bet Apple is doing everything they can to figure out how and fix it.

[tremon]

GPLv3 mandates that your hardware be insecure

Oh please. It really doesn't, it merely mandates that the user is able to override a manufacturer's lockdown. Not that any nitwit should be able to override a user's lockdown.

[eridius]

A platform that is insecure-by-default and relies on users being knowledgeable and motivated enough to learn how to lock down their own devices is still an insecure platform.

[paxcoder]

People have taken their time to draw you a picture of a solution you could have come up with yourself. They are not talking about opt-in security, you are the only one. GPLv3 does not hinder security. You are furthering FUD.

[jordigh]

> Also don't forget the patent stuff in GPLv3. That's not quite as scary as the anti-TiVoization stuff, but it's still pretty significant for large companies.

The Apache license has a nearly identical clause (in fact, I believe GPLv3 was inspired from the Apache license) and companies like Google and Apple have used the Apache license without destroying their business. Anti-retaliation clauses don't seem to be a death knell.

http://en.swpat.org/wiki/Patent_clauses_in_software_licences...

[eridius]

GPLv3's patent clause is effectively identical to Apache License, Version 2.0? I wasn't aware of that. I haven't done much research on the patent angle, I only brought it up because I actually talked to one of Apple's lawyers at one point about GPLv3 and they brought up the patent stuff as an issue.