Developer ID might not seem restrictive, but it is

I need to talk about Gatekeeper and Developer ID.

In short, I am very uncomfortable with this previewed security feature of Mountain Lion. Apple is trying to assure that users are only going to be safer and that developers are still going to be able to do business as usual, but the Mac ecosystem is not limited to these two parties and this ignores pretty much everyone else: for these people Gatekeeper is going to be a problem. Enough so to make me consider switching.

I don’t mean to say it’s all bad, as Apple is set to allow more at the same time as it allows less. Indeed, with Developer ID Apple is clearly undertaking better support of apps from outside the Mac App Store, if only because they will have to maintain this system going forward, and I can only hope this support will improve in other areas (such as distribution: disk images are long past cutting edge). But while Apple gives with one hand, it takes away with the other, as Mountain Lion will by default (at least as of the current betas, though that seems unlikely to change) reject unsigned apps and apps signed by certificates other than Mac App Store and Developer ID ones; of course most people will not change that default, and so you will have trouble getting these people to run your code unless you get at least a Developer ID from Apple, and while better than requiring you to go through the Mac App Store this requirement is quite restrictive too.

The matter is not that with Developer ID apps will now be exposed to being blacklisted by Apple; honestly, speaking as a developer I personally do not mind this bit of accountability. Maybe there are going to be issues with this power now entrusted to the hands of Apple, such as the possibility of authorities (through executive branch bullying, or with a proper court order) asking Apple to neutralize an app perceived as illegal, but if this ever happens I believe the first incidents will cause this eventuality to be properly restricted by law.

No, the matter, as I wrote to Wil Shipley in an email after his proposal, is that many people who are important to the Mac platform are going to be inconvenienced with this, as getting a Developer ID requires a Mac Developer Program membership.

  • Sysadmins/IT people, to begin with, often need to deploy scripts, and either those don’t need to be signed, and they become the new malware vectors, or they do (Apple could define an xattr that would store the signature for a script) and then any company deploying Macs needs to enter the Mac Developer Program and manage a Developer ID that IT needs to be able to access day to day (that is, not just for releases, like in a software company) and so could leak, just so that the company can service its own Macs internally.

  • Then we have people using open-source tools that Apple doesn’t provide, such as lynx, ffmpeg, httrack, mercurial, etc., and who likely get them from projects like MacPorts; maybe we have an exception for executables that were built on the same machine, but how is it enforced then?

  • Student developers have historically been very important to the Mac platform, if only because many current Mac developers started out as such. If entering the Mac Developer Program is required to distribute Mac apps in the future, it’s a threshold that many will not clear, and as a result they will not get precious feedback from other people using their code, or worse they will not choose Mac development as a career as they could have if they had been encouraged to do so by people using their software (for instance, Jeff Vogel wasn’t planning on making Mac games as a career, but he quit grad school when Exile started becoming popular). At 99$ (per year), it seems silly to consider the cost of the Mac Developer Program as an obstacle, especially when compared to the cost of a Mac, but you have to consider the Mac likely benefitted from a student discount and was possibly entirely paid by the family; not so for the Mac Developer Program. Regardless, any extra expense will, rationally or not, cause it not to be taken by a significant portion of the people who would have otherwise tried it, even if it would have paid for itself eventually.

  • Many users will tinker with their apps for perfectly legitimate reasons, for instance in order to localize it and then submit the localization to the author, or in the case of games to create alternate scenarios or complete mods. It’s something that I am particularly sensitive to, as for a long time I have both enjoyed other’s people’s mods and conversely tinkered myself and shared with others: I have created mods, documented the formats to help others create mods, extracted data from the game files, gave tips and tricks and development feedback on other people’s in-progress mods, I was even at some point in charge of approving mods for a game to the official mods repository, and I created tools to help develop mods (more on that later). The user modding tradition is very strong in the Ambrosia Software games community, going back to Maelstrom nearly 20 years ago, and that’s merely the one community I am most familiar with. However, tinkering in such ways typically breaks the app signature; an app with an invalid signature will currently run on Lion (I know it if only because my Dock currently has an invalid signature), but it will likely change with Mountain Lion as otherwise Gatekeeper would be pointless (an important attack to protect against is legitimate apps that have been modified to insert a malicious payload and then redistributed). So we will have to rely on developers excluding files that could be desirable for users to tinker with from the signature seal… well, except that the developer will then need to make sure the app cannot be compromised if the files outside the seal are, and I’m pretty sure it’s impossible to do so for nibs for instance, so app developers will not be able to simply leave the nibs out of the seal so that users may localize them; they will need to roll out systems like the one Wil Shipley developed for localizations, completely out of the realm of Apple-provided tooling.

  • Power users/budding developers will often create small programs whose sole purpose is to help users of a main program (typically a game, but not always), for instance by interpreting some files and/or performing some useful calculations; they typically develop it for themselves, and share it for free with other users in the community of the main program. It’s something I have done myself, again for Ambrosia games, and it’s a very instructive experience: you start with an already determined problem, file format, etc., so you don’t have to invent everything from scratch which often intimidates budding developers. However, if it is required to register in the Mac Developer Program to distribute those then power users will keep those to themselves and they won’t benefit from the feedback, and other users won’t benefit from these tools.

(Note that Gatekeeper is currently tied to the quarantine system, and so in that configuration some of the problems I mentioned do not currently apply, but let’s be realistic: it won’t remain the case forever, if only so that Apple can have the possibility of neutralizing rogue apps even after they have been launched once.)

In fact, a common theme here is that of future developers. Focusing solely on users and app developers ignores the fact that Mac application developers don’t become so overnight, but instead typically start experimenting on their spare time, in an important intermediate step before going fully professional; it is possible to become an app developer without this step, but then the developer won’t have had the practice he could have gotten by experimenting before he goes pro. Or worse, he will have experimented on Windows, Linux, or the web, and gotten exactly the wrong lessons for making Mac applications—if he decides he wants to target the Mac at all in the end.

Because of my history, I care a lot about this matter, especially the last two examples I gave, and so I swore that if Apple were to require code to be signed by an authority that ultimately derives from Apple in order to run on the Mac, such that one would have to pay Apple for the privilege to distribute one’s own Mac software (as would be the case with Developer ID), then I would switch away from the Mac. But here Apple threw me a curveball, as it is the case by default, but users can choose to allow everything, but should that matter, since the default is what most people will ever know? Argh! I don’t know what to think.

In fact, at the same time I am worrying about the security of the whole system and wish for it to be properly secure: I know that any system that allows unsigned code to run is subject to the dancing bunnies problem; and maybe the two are in fact irreconcilable and it is reality itself I am having a problem with. I don’t know. Maybe Apple could allow some unsigned apps to run by default, on condition they have practically all the sandboxing restrictions to limit their impact. The only thing is, in order to be able to do anything interesting, these apps would at least have to have access to files given to them, and even that, combined with some social engineering, would be enough for malware to do harm, as users likely won’t treat these unsigned apps differently from regular desktop apps, which they consider “safe”. Maybe the only viable solution for distribution of tinkerer apps are as web apps (I hear there is work going on to allow those to access user files); I don’t like that very much (e.g. JavaScript is not very good to parse arbitrary files), but at the same time users do tend to take web apps with more caution than they take desktop apps (at least as far as giving them files goes, I hope), and any alternate “hyper sandboxed” system that would be introduced would have to compensate the 15+ years head start the web has in setting user expectations.

The same way, the very same cost of the Mac Developer Program which is a problematic threshold for many is also the speed bump that will make it economically unviable for a malware distributor who just had its certificate revoked to get a new one again and again.

This is why, paradoxically, I wish for iOS to take over the desktop, as by then iOS will likely have gained the possibility to run unsigned apps, and users having had their expectations set by years of being able to use only (relatively) safe iOS App Store apps will see these unsigned apps differently than they do apps from the store.

Anyway, nothing that has been presented about Mountain Lion so far is final, and important details could change before release, so it’s no use getting too worked up based on the information we know today. But I am worried, very worried.

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