“Packages should be reproducible” added to Debian Policy

Such randomization can mitigate against certain kinds of attacks, especially making particular instances of an attack work differently between each kernel build, and thus increasing the difficulty of writing exploits that work across a broad range of kernel builds. There are about 30 different patch releases of the kernel for Debian Jessie alone; so such randomness, if applied across the different builds of a kernel within a release, across various different Debian releases, across different architectures, and also applied by other distros, can substantially increase the difficulty of writing an exploit that can affect a substantial fraction of Linux systems on the net.

That helps provide a form of "herd immunity", where the herd is all deployed Linux systems on the net. It doesn't provide any real protection for a particular build; so it's no harder to write an exploit that targets all system running the exact same kernel. But it does dramatically increase the difficulty of writing a widespread worm which relies on the given exploit, and which can easily spread between a variety of different systems.

Anyhow, that footnote was on a policy for explicit exceptions from the general policy. The general policy is that yes, builds should be reproducible, and any randomness should be generated locally. The footnote was giving a few example of potential exceptions which may be required, as a way of demonstrating that it would be fine to have the general requirement be reproducible builds with case-by-case, narrow exceptions for cases in which non-reproducible builds provide significant value.

And note that such exceptions may be based on how an upstream project operates. If the upstream kernel has some modules that build non-reproducibly in such a way, it may be more viable to encode an explicit exception to the policy for that case, than to remove that non-reproducibility.

It's important to keep in mind that someone applying a cleanup once accidentally removed almost all entropy from OpenSSL's random number generator on Debian (they even asked for review from upstream, and failed to get it, because of the confusing naming of upstream's mailing lists). Having an excessively rigid policy could mean that Debian maintainers would be forced to remove features that do provide some kind of benefit.

>Like if 500 people can independently confirm a build produces a binary with result X then they could all share in the reward, whatever that is.

In a cryptocurrency blockchain, every single node verifies every block received from another node in order to check whether it should be included in the node's local copy of the blockchain. If computing and verifying are the same operation, it's not "500 people independently verify a source produces a given binary and the rest of the network rewards them", but "the entire network verifies that a source produces a given binary and they all equally pat each other on the back". Unless you only reward the first to verify a build, but then no node would bother spending time verifying blocks made by other people and building off that chain rather than mining its own blocks if they both take as long as each other.

>The problem is in verifying that someone actually did the work and didn't steal someone else's solution.

Bitcoin uses the hash of the rest of the block (which includes the address for the reward of the miner who is doing the proof-of-work) as an input into the proof-of-work such that the result of the proof-of-work is only valid for that input. It's not apparent to me whether where there could be room to add an input like that into checking whether a source compiles to a binary. (I thought through whether you could make a Lamport-signature-like scheme involving picking specific intermediate values generated during the compilation that correspond to parts from a pre-committed series of hash pairs, but then I realized it wouldn't work because anyone who does the build once would get all of the intermediate values and be able to create as many of these signatures as they wanted for little effort.)

>Maybe encrypting the result you get and sending it off in escrow to a centralized verification location would work, and once a sufficient number of solutions are collected the solutions are unsealed and the results shared so everyone can see what happened and raise any objections.

Sounds like what you're looking for is some kind of web-of-trust reputation system with a trusted authority rather than a cryptocurrency blockchain. (If you have a trusted authority, then nearly all of the design of a bitcoin-like cryptocurrency is ridiculous dead weight. You can shed nearly everything, you don't need a broadcast-everything blockchain, and you could choose to have really cool things like blind signatures for anonymous transactions.) (Though if you have a trusted authority who can afford to be running build processes, it'd be a lot simpler to just have them do all the build-verifying for you, and you could do away with anything discussed in this post and just have them publish a PGP/HTTPS-encrypted webpage with their results.)

1. Too few marketing. I only heard of Nix for the first time last year.

2. When you boot a virtual server, the UI usually offers you Debian, Ubuntu and Centos/RHEL images, sometimes Suse/SLES or Arch. So again, less visibility, and if the hoster does not allow you to bring your own image, it's a pain in the ass to install anything else.

3. (Going off topic for a second: I probably would have switched to Nix(OS) already if it wouldn't entail effectively abandoning the configuration management tool that I maintain.)