AOSP having a regression causing a timestamp to be added somewhere isn't a reasonable justification for blocking security updates. No system without the ability to investigate the cause and determine if it's okay would be reasonable. We would need to finally have early access to new Android releases to test this in advance and have fixes ready to go prior to the stable releases. We do not currently have this early access but will likely obtain it from the OEM we're working with soon. We would still need additional resources to have ongoing testing for this and fixes for any relevant regression that finds. Porting to new releases prior to them being stable and specifically testing this would be needed.

We can't risk introducing a very a fragile system which could result in substantially delayed updates. Our plan for reproducible builds is to provide an opt-in feature where people can select which additional parties they trust to reproduce builds without falling behind significantly. This would solely be for the OS update client and App Store updates. It would not be for other uses of signing such as verified boot which are not designed to handle this. It would a system to verify that signed hashes from other parties have been published for an update. The meaning of that can be defined by these parties reproducing builds, such as how they'll investigate a mismatch and the way they'll determine if it's an issue.

In practice, this would be based on tools we publish for others to use for building and comparing. Similar to the rest, people are trusting the source code and the people who wrote it. Source code is not inherently trustworthy and provides no magical privacy or security properties. Reading the sources does not mean you will find all the vulnerabilities, particularly subtle ones or hidden ones. It clearly doesn't provide that even for extensive audits/review. Why does the Linux kernel have so many serious vulnerabilities being found on a regular basis including ones which are years and even decades old if this approach works?

If you truly believe that I'm insane, why do you think it's reasonable to use code that I wrote or supervise writing as long as the build matches the sources?

> Until at least those points are covered, the centralized trust model of GrapheneOS is a liability and the central keyholder is at high risk of being targeted for manipulation or coercion.

You use many open source projects with far fewer review. GrapheneOS itself is based on AOSP which uses a huge number of open source projects from a huge number of people. The Linux kernel alone has a massive number of contributors and most code has little review. It's filled with vulnerabilities which are found regularly. https://lore.kernel.org/linux-cve-announce/ provides a very flawed overview of this based on what is backported. These devices are compromised in the real world by exploiting vulnerabilities like many of these. Reproducible builds and checking that others have reproduced builds is not actually going to stop a software supply chain attack in practice, which would work within the constraints and use source code. If one of the projects used by AOSP has a backdoor added to the sources, how do reproducible builds help? We'd just be building the code and the backdoor would be reproducible.

> Honestly there is no good solution to these problems right now, and as a security and privacy researcher my best advice today to potentially targeted individuals is don't carry a phone at all, or if you must carry one, keep it in airplane mode whenever possible and do not do anything sensitive on it. Consider QubesOS or AirgapOS for such things.

Computers have closed source hardware and firmware in general. A few small closed source libraries are not significant compared to the overall complexity of the closed source hardware and firmware. Those libraries are easy enough to review. Pixels have debug symbols enabled for them. Reviewing firmware is a larger scale and much harder undertaking. How do you review the hardware itself? Even if the hardware design was fully open source for the SoC including the CPUs, GPUs, MMU and everything else along with the radios and other peripherals, how would you verify that what a chip manufacturer like TSMC produced matches the hardware design?

> If you are fine with centralized control of a phone, and fine with binary blobs controlled by random corpos having God access to your device, but would prefer to eliminate as much proprietary corpotech bullshit as possible, then I would suggest considering CalyxOS which is at least run by a former LineageOS maintainer with a great reputation.

The lead developer of CalyxOS is a former Copperhead employee directly involved in the takeover attempt on GrapheneOS in 2018. You're talking about someone who was a direct participant in doing shady things for Copperhead's CEO going against the ethics of the open source project the company was meant to be supporting including participating in the takeover attempt and then leaving following it.

He was involved in subsequent attacks on GrapheneOS including similar harassment to what you participate in yourself. CalyxOS does not have current Android privacy/security patches. It's still missing the June 2025 patches for Pixel drivers/firmware. It isn't a hardened OS like GrapheneOS with similar privacy or security improvements, and it doesn't maintain all of the standard security model due to the privileged code they add to the OS.