Android Security Whitepaper 2024

Privacy
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That was a lovely read, thanks for sharing.

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You got a TLDR?

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Not a TLDR on the PDF (any widely-accessible LLM could do that for you), but what I shared on Hacker News some 2 years ago (link) serves as a good overview of where Android is headed:

ex-AOSP dev here

Android and ChromiumOS are likely the most trustable computing platforms out there; doubly so for Android running on Pixels. If you don’t prefer the ROM Google ships with, you can flash GrapheneOS or CalyxOS and relock the bootloader.

Pixels have several protections in place:

  • Hardware root of trust: This is the anchor on which the entire TCB (trusted computing base) is built.

  • Cryptographic verification (verified boot) of all the bootloaders (IPL, SPL), the kernels (Linux and LittleKernel), and the device tree.

  • Integrity verification (dm-verity) of the contents of the ROM (/system partition which contains privileged OEM software).

  • File-based Encryption (fscrypt) of user data (/data partition where installed apps and data go) and adopted external storage (/sdcard); decrypted only with user credentials.

  • Running blobs traditionally run in higher exception levels (like ARM EL2) in a restricted, mutually untrusted VM.

  • Continued modularization of core ROM components so that they could be updated just like any other Android app, ie without having to update the entire OS.

  • Heavily sandboxed userspace, where each app has very limited view of the rest of the system, typically gated by Android-enforced permissions, seccomp filters, selinux policies, posix ACLs, and linux capabilities.

  • Private Compute Core for PII (personally identifiable information) workloads. And Trusty Execution Environment for high-trust workloads.

This is not to say Android is without exploits, but it seems it is most further ahead of the mainstream OSes. This is not a particularly high bar because of closed-source firmware and baseband, but this ties in generally with the need to trust the hardware vendors themselves (see point #1).

And since I wrote that, ChromiumOS is decisively being folded into Android (ref).

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