[Nexus 5 Q&A, Help & Troubleshooting] Lucian Armasu:
I. Is there no way to use TrustZone or something that doesn't give root access to it, so that rooted users could still use Android Pay?

Either way, why doesn't Google allow for some kind of "high-privilege" account, like we have on Windows or other operating systems? Keep the default as limited as you want, but when you create a new account/profile on your phone, you should be able to select "Admin" or "Super-user" or something.

However this account shouldn't give FULL root powers, that could affect the whole phone. In fact, there should be ZERO interaction between the accounts (I don't think right now that is true? I think I've noticed my Wi-Fi stays connected in the new account, for instance, which SHOULD NOT happen), and enforce that through SELinux if possible.

The Super-user/Admin account should give enough privileges that 90% of "root apps" would work on it. This level of privilege should also not be able to modify the fingerprint stuff. And there should still be the same protections as in the limited account, but instead of enforcing them, they should be in "ask mode" (which I realize would still make the "Super-user" less safe than the default account, but better than to allow everything by default in it, even if it annoys the users a little).

What I'm saying is that even if users "take full responsibility" for using a Superuser account, they should still be protected somehow against malware or doing dumb things, but that enforcement shouldn't be mandatory as it is in the limited account. By the way by "super-user" I don't mean the "superuser" in Linux, so sorry if that makes it confusing. I just mean a "higher-privilege" level in general than the default Android accounts/profiles.

Now the question is why would Google even do this? Because there are quite a few people (millions actually) that want to do "more" with their phones, and I believe Google can provide that in a "safer" way, instead of forcing them to come up with root exploits to do what they want with their phones, which not only essentially creates a "free-exploit market" for Android, but makes the phones less secure, too. It would also be great if Google mandated that ALL bootloaders can be unlocked the way they can be in Nexus phones.

II. And since we've got an Android security guy here, any chance Android would adopt Grsecurity/Pax mitigations in the near future? I think we'll begin to see this more and more from some OEMs, such as Blackberry and Copperhead. If not, why not?

III. I also do hope you guys have already been working on a way to bring security updates (at the very least) to all Android devices, even if it's a 5-10 year project. It simply NEEDS to happen. It's by far Android's biggest security problem. iPhones are now getting updates for FOUR YEARS for crying out loud.

Work with ARM, work with OEMs, with component makers - whatever needs to happen to make Android hardware and software more standardized in the future so something like that can be made possible. Microsoft solved this problem. Linux did, too. I'm sure it can eventually be solved in Android as well. But of course it will never happen if Google isn't even considering it a problem and doesn't actively work on it to solve it.

Where does Microsoft makes the most money with Windows? It's in enterprise. Why would the enterprise customers trust Windows, despite all of its security flaws and viruses written for it in the past? Because Microsoft provides support and updates. So even if Google considers updates only a problem for "Android geeks" because "normal users don't care anyway", Google is actually losing a huge opportunity to make Android popular in the enterprise market here. The enterprise market will end up dominated by Microsoft and Apple and Android will be nowhere to be seen because nobody wants to deal with Android's (frankly) pathetic 18 months of support (which is among the best you can hope for right now).