alt.hn

5/10/2026 at 5:26:03 AM

Debian must ship reproducible packages

 https://lists.debian.org/debian-devel-announce/2026/05/msg00001.html

by robalni

5/10/2026 at 9:47:40 AM

This is a huge achievement for Debian and the free software world.

It took a while though until this was understood. In 2007 when pointing out on debian-devel that this is needed, I was still told what huge waste of time this would be. And indeed it took a huge amount of work by many people to get there, but it is well worth it.

by uecker

5/10/2026 at 10:09:37 AM

There was no bug or attack on Debian since 2007 that reproducible packages would prevent.

"Well worth it" is not correct. And it just ups the the contribution barrier to Debian higher, I already heard a lot of people complaining that contributing to Debian is hard and while in past I defended it by "they need all the checks and bounds to make sure packages play with eachother nicely", this is just step that makes it hard for no reason and little benefit.

by PunchyHamster

5/10/2026 at 10:34:25 AM

” If you are wondering why we are doing this at all, then hopefully the Reproducible Builds website will explain why this is useful.”

https://reproducible-builds.org/

Could you perhaps respond to the argumentation here?

by savolai

5/10/2026 at 12:43:52 PM

(Not OP, but...) I still fail to see the current value in confirming that a reproducing builder also included the same compromised dependency that I did when I built it. I understand that reproducible builds are guarding against dynamic attacks within build infrastructure. However I just don't see those happening. Compromised source dependencies are a 100x more common problem.

by dvogel

5/10/2026 at 2:24:47 PM

I agree that compromised source dependencies are the bigger problem, but that doesn't mean a compromised build infrastructure isn't. Just this last week, we had two Linux kernel LPEs that could have been leveraged to implement just such an attack, for example.

Another thing to consider is that Debian has quite a few derivatives who may also rebuild packages from source, so you have a multiplier there.

by ckastner

5/10/2026 at 2:00:37 PM

https://en.wikipedia.org/wiki/XZ_Utils_backdoor

by fsflover

5/10/2026 at 3:15:31 PM

that's example of attack reproducible packages do not protect from, why you are linking it ?

by PunchyHamster

5/10/2026 at 3:23:27 PM

A distro automatically verifying that installed packages are reproducible would protect the user?

by fsflover

5/10/2026 at 4:49:06 PM

No, it wouldn't. The xzutils attacker compromised the source repository. The build pipeline portions were used to obscure the purpose of the exploit embedded in the source code repository.

by dvogel

5/11/2026 at 12:40:48 AM

Your wrong. It was both. The payload was embedded in the binary blob test file. The mechanism to pull it into the build was added to the release tarball only.

Here's the quote from the guy that discovered it in the initial public disclosure [1]:

  After observing a few odd symptoms around liblzma (part of the xz package) on Debian sid installations over the last weeks (logins with ssh taking a lot of CPU, valgrind errors) I figured out the answer. The upstream xz repository and the xz tarballs have been backdoored. At first I thought this was a compromise of debian's package, but it turns out to be upstream. One portion of the backdoor is *solely in the distributed tarballs* and debian's import of the tarball ... it is also present in the tarballs for 5.6.0 and 5.6.1.
[1]: https://www.openwall.com/lists/oss-security/2024/03/29/4

by theteapot

5/11/2026 at 5:42:16 AM

You're mistaking a compromised build pipeline versus a compromised source repo that only triggers in some build pipelines. You can do reproducible builds from compromised source tarballs. Nothing about reproducible builds necessarily requires source control. Yes, if some people who built from source control compared their builds to the builds from the tarballs it could detect the xzutils compromise. However I have yet to see a reproducible build project that includes such cross-build checks.

by dvogel

5/11/2026 at 6:27:42 AM

> Yes, if some people who built from source control compared their builds to the builds from the tarballs it could detect the xzutils compromise.

Good. Then we are on the same page.

by theteapot

5/11/2026 at 6:16:29 AM

Nowadays you would work in git and then you would be able to easily detect any discrepancy between the upstream tar ball and the upstream source imported via git. But yes, better support for securing more of the process is needed.

by uecker

5/11/2026 at 12:33:20 AM

In xz-utils hack the attacker slipped changes into the Github release tarball that were not present in the Github version / git commit history. The Debian maintainer built from the release tarball instead of just pulling from the git repo directly. Shouldn't have been doing that but good luck convincing him not to use the workflow he's been using for the last X years (I tried). With repro builds we can clone the git directly confirm we get the same build.

by theteapot

5/10/2026 at 3:14:01 PM

I know why they are useful. I am arguing they are waste of time for effort involved.

Forcing devs to use hardware keys to sign commits/CI requests would be actual security improvement, thwarting many supply chain attacks that only worked coz the attacker got to developer credentials. Hardware keys at least have option to make some operations require physically pressing the key so there is chance developer will notice.

But thanks to reproducible builds, at least someone can... validate that the binary code of vulnerable package can be reproduced. Very fucking useful.

I am not saying it is useless. I am saying it is one of highest hanging fruits on security tree.

by PunchyHamster

5/10/2026 at 4:11:24 PM

A hardware key does not help if the developer's machine is compromised, as there is no change to understand what is signed anymore, or do you think the hardware key will show all the source code on its little display before signing?

With reproducible builds, you do not need to trust that the system that build the binary was not compromised, because this would be detected immediately.

Source compromises are still an issue, but there is a much bigger change that they are detected. Also if there is a compromise, reproducible builds allow you to later track it to the source. For an infected binary it is much more difficult to understand how it got there and what else might be compromised.

by uecker

5/10/2026 at 5:33:48 PM

The way at least YK works is that you can set it up that pressing a key is requires for signing so at least "silently steals creds and sends malicious code" case (which is vast majority of compromises) gets handled

> Also if there is a compromise, reproducible builds allow you to later track it to the source.

They do not. Git log and build logs allow for that.

Reproductive builds only have value after the source. They protect build servers from being compromised (and then only if some other uncompromised environment is also running verification passes), if the bug is at source reproductive builds are exactly as valuable as writing commit that was used for build in app's code/package metadata.

by PunchyHamster

5/10/2026 at 6:53:12 PM

If your compiler (or other tool or automatic build environment) is compromised and inserts a backdoor in the binary during building, the fact that you need to hold a key while signing or not is completely irrelevant.

git log and build logs do not help you at all, if you can not even determine that the compromised binary has any relation to the build log or the source you may want to look it. This is what reproducible builds give you. You are right that it does not protect against compromised sources.

by uecker

5/10/2026 at 10:10:51 PM

> I know why they are useful. I am arguing they are waste of time for effort involved.

Not being reproducible is a bug.

There is no reason for a build to not be reproducible, but somehow we let the built binaries become infested with timestamps, login names and file system paths. We recently moved to reproducible builds at work, and discovered that our login names and local home directory paths were being shipped in every release. No one was was very happy about leaking PPI like that.

You may not consider it worth the effort, but you aren't the one putting in the effort so I'm not sure why that matters to you. It is very much worth the effort to those people doing the work. Debian is a do-orcracy and so the people doing the work get to make the decisions.

by rstuart4133

5/11/2026 at 8:14:04 AM

Sure. The site appears to be a bunch of warm-fuzzies that could apply to almost any other measure you take, it's nothing specific to reproducible builds. As the original poster said "There was no bug or attack on Debian since 2007 that reproducible packages would prevent". In fact, it could be argued that reproducible builds lead to a reduction in security, not an improvement: They give an attacker an exact fixed memory layout for all of the binaries, so if you develop something like a ROP exploit for a copy on your local system you know that exploit will work on every other system as well because the binary layout is identical. It's a perfect monoculture where everything is vulnerable to the same exploit. It seems to have been something created by geeks to impress other geeks, without any considerations for whether it has any actual benefit or not.

by pseudohadamard

5/11/2026 at 8:48:00 AM

This comment is misinformed. Non-deterministic builds would also result in one tarball redistributed to all distro users. The ROP exploits don't work because of ASLR.

by stabbles

5/12/2026 at 4:27:40 AM

ASLR makes ROP attacks harder, it doesn't stop them, as a great many successful attacks have demonstrated. Heck, bypassing ASLR is taught to students at MIT... can't find the direct link ATM but here's a student assignment, https://csg.csail.mit.edu/6.S983/labs/aslr/.

by pseudohadamard

5/13/2026 at 5:36:08 AM

This does not make your comment above less wrong.

by uecker

5/10/2026 at 11:02:46 AM

Reproducible builds are applicable not only to respond to ‘attacks’, a subject you seem to be bikeshedding, but also for other reasons too.

Anyone having to maintain a code base or a distributed fleet of devices will gain from this decision, immensely, as their operational periods come and go.

Reproducible builds are about longevity as much as they are about security.

Please don’t make bold claims about ‘no reason and little benefit’ while demonstrating ignorance of this hard fact: reproducible builds should have been the norm, in computing, from the get-go.

by MomsAVoxell

5/10/2026 at 11:29:46 AM

I longevity is harmed though. Your certs need to expire in a few years we think that your toolchain will not be downloadable.

by bluGill

5/10/2026 at 12:13:03 PM

Those problems need to be solved as well.

by MomsAVoxell

5/10/2026 at 12:16:22 PM

I don't think they do, actually. Longevity sounds good, but in reality anything that's old probably has critical security holes and so you shouldn't use it anyway.

by bluGill

5/11/2026 at 2:53:38 PM

You probably don’t know how industrial computing works.

Toolchains absolutely need to be maintained with some degree of longevity.

The whole world doesn’t march to your consumer-user beat. Sometimes it functions at industrial-user tempo’s, too ..

by MomsAVoxell

5/10/2026 at 1:23:50 PM

A warning is sufficient. Old tech should continue to work, for preservation and archival reasons.

by iamnothere

5/10/2026 at 10:10:53 PM

I've long ago realized that archival needs to be a separate task left to archivists and archive systems. If you take it into account when designing a live system it's liable to seriously compromise your system design.

Say you're making a chat app - you wouldn't incorporate a delete feature, and you might be tempted to use some kind of blockchain to prove all messages were delivered without gaps. But if you ignore archival needs you design something similar to IRC which is much simpler.

by tardedmeme

5/11/2026 at 1:59:24 PM

That depends on your user base. If your group of target users includes professional, corporate, or governmental use, then you absolutely need to build in signing and archival for legal reasons. If your users include people who may only connect occasionally or with flaky connections, then you need a robust way to ensure that messages are held for delivery and that all messages are delivered in order. Basic chat (without delivery guarantees or archival) is already solved by IRC, long ago.

by iamnothere

5/10/2026 at 5:37:34 PM

just archiving binary artifacts and source packages is enough

Reproducibility adds nothing here

by PunchyHamster

5/11/2026 at 6:13:20 AM

It sure does: no need to keep the binaries around if they are reproducible.

by MomsAVoxell

5/11/2026 at 6:12:39 AM

You’re not thinking like an industrial user but rather as a consumer. Maybe you should extend your scope a little bit.

by MomsAVoxell

5/11/2026 at 1:07:36 PM

Industry is learning - often the hard way that out of date software is only acceptable if the device is not connected to a network at all. Even government labs with a separate top secret network that isn't supposed to be connected to anything else get hacked from the internet.

Not that you are wrong, industry keeps thinking they can make themselves immune and so long term reproducibility is useful, but I submit they are wrong.

by bluGill

5/11/2026 at 2:55:39 PM

Disclaimer: I work in the safety-critical/industrial sector of software.

Literally none of your statements are applicable to that realm, sorry.

Rail operators have long since been operating their air-gapped infrastructure with 99.999% safety results, literally not adhering to any of the policies you claim are endemic to the industry.

by MomsAVoxell

5/10/2026 at 5:36:48 PM

> Anyone having to maintain a code base or a distributed fleet of devices will gain from this decision, immensely, as their operational periods come and go.

Just baking in build ID and commit is enough. What you think reproducible builds add ?

> Please don’t make bold claims about ‘no reason and little benefit’ while demonstrating ignorance of this hard fact: reproducible builds should have been the norm, in computing, from the get-go.

So far not a single person in the thread gave me concrete example (as in existing project, existing problem, no other solution can solve it). Just claiming it's better based on their feelings. Come on, be the first one.

by PunchyHamster

5/11/2026 at 6:15:54 AM

I already gave you an example, you dismissed it because you know better, but it is clear that you haven’t thought this through from the perspective of systems designers who have to deploy a base OS, with expected lifetimes of years, across a large fleet of devices.

Think industrial applications, such as rail and heavy industry transportation. We use reproducible builds here as part of a wider safety-critical protocol which guarantees that what we are running is what we expect to run - nothing more, nothing less.

Reproducible builds are certifiable. They can be relied on in environments where certification costs millions and takes years.

Think outside your consumer box for a minute.

by MomsAVoxell

5/10/2026 at 10:36:11 AM

Reproducible builds reduce the need for trusted parties.

Have many organizations produce the binaries independently and post the arifacts.

Once n of m parties agree on the arifact hash, take that as the trusted build.

If every party reaches a different hash then we cannot build consensus.

by azkalam

5/10/2026 at 12:25:41 PM

To move away from organizational dependence, there should be an installable project for debian where I can dedicate some configurable small percentage of my compute when idle to reproducibly building debian components to make a robust verification system, starting with the most critical code.

Obviously, it would be a ton of work to make such a system resistant to gaming by malicious actors (see GNU Guix for useful efforts), but it would provide valuable diversity in architecture and (political or other) control.

It would be even cooler if we could have independent projects that could run on various distros and OS, and build packages for any of them. Having packages for bsd verified on linux and vice-versa with statistical logging (this code has been verified x times on y OSes) would be reassuring.

by sgc

5/10/2026 at 3:16:19 PM

I think that project is called Ubuntu.

by PunchyHamster

5/10/2026 at 5:21:14 PM

I don't know of anything Ubuntu is doing that is significantly beyond what Debian is doing in this regard, nor that they have a distributed reproduction system set up???

by sgc

5/10/2026 at 3:38:34 PM

Building Ubuntu does not produce identical binaries to Debian, so no, that's not what they're asking for

by saghm

5/10/2026 at 1:15:04 PM

Is the "Jia Tan" XZ Utils compromise not a good example? That relied on code snuck into a release that was not in source.

(It was caught before being promoted into a stable Debian release, yes, but this sort of relied on a happy accident, too close for comfort)

by benregenspan

5/10/2026 at 1:21:43 PM

The xz hack was still reproducible, because it was included in the distribution archive which did not match the upstream source -- even then, it was so obfuscated it likely would have gone unnoticed, but nevertheless it only lived in the uploaded tarball and not in the repo. Reproducibility is a good thing, but the next step is build provenance.

Still, lots of good non-security benefits to reproducible builds too.

by chuckadams

5/10/2026 at 2:54:32 PM

The xz utils compromise is a very good example... of why reproducible packages doesn't actually solve anything security-wise!

The backdoor relied first on a difference between building a package in a packaging environment versus building the package on your own. And also, it relied on the very common practice of checking in unreviewable artifacts into the source tree (e.g., the configure script, malicious binary test artifacts).

Reproducible builds guarantee that two people can follow the same instructions and get the same, bit-identical outcome. It does nothing to guarantee that those instructions have not been compromised, and all of the great packaging security failures of my lifetime that I can think of have relied on those instructions being compromised (e.g., xz utils, Debian OpenSSL keygen issues).

by jcranmer

5/10/2026 at 3:52:41 PM

An attack would be far easier without reproducible packages. One could upload a compromised binary to debian by becoming a debian developer, blackmail a debian developer to so, or compromise the computer of a debian developer or the distribution.

At the time of xz attack, the package was already reproducible.

by uecker

5/10/2026 at 6:15:39 PM

I'll give an analogy to email and spam. A lot of effort has been spent making sure that if an email is from x@example.com, it actually came from x@example.com, giving us things like SPF, DKIM, and DMARC. And it turns out that the most eager adopters of the newest technology are... the spammers themselves! Because they don't need to lie about their email address; they can have that be completely honest, and instead resort to other tricks to mislead users as to who they are (e.g., the display name, which most email clients blindly trust and happily display).

Similarly for package managers, the biggest issues are typo-squatting or maintainer credentials compromise. And in neither case does the attacker have any incentive to take advantage of it in a way that breaks reproducibility--they can be completely honest about what they're doing. Now even if I were an attacker who had compromised a maintainer's machine, I'd still probably go for compromising the source rather than compromising the final artifact-generation process... simply because compromising the source makes the exploit live longer.

As xz shows, once you have a compromised maintainer, there's basically nothing you can do to fix it except by having someone else discover the compromise and locking out the maintainer.

by jcranmer

5/10/2026 at 7:00:07 PM

Typo-squatting attacks are more of an issue for non-curated software collections, not so much for Debian. If you use npm or cargo or similar, then you have indeed far bigger worries. Compromising the source has the disadvantage for the attacker that it much easier to detect. Again, if you always install the newest things from an non-curated collection that may not matter much, but for something such as Debian, this increases the probability of detection a lot. One can argue that xz shows that it is possible to hide things in the source, but it also shows how much effort was needed to do this. (and the xz package was reproducible, so compromising the debian system and uploading a binary would have a high risk of detection. That this was not done can therefor not serve as evidence that binary attacks are not an issue. )

by uecker

5/10/2026 at 3:18:32 PM

No, reproducible builds make such backdoors more difficult to sneak in together with other checks.

by goodpoint

5/10/2026 at 10:46:10 AM

It makes shipping backdoors a whole lot harder, yes.

by eptcyka

5/10/2026 at 5:38:16 PM

Unless someone spins entirely separate infrastructure dedicated just for verifying Debian packages, it doesn't.

by PunchyHamster

5/10/2026 at 11:50:54 AM

Hmm, it prevents Trojan binaries which is a small subset of backdoor IMHO.

Defense in depth obviously is a good thing

by zaphirplane

5/10/2026 at 10:12:29 AM

There was perhaps no detected bug or attack. There have most likely been bugs or attacks that reproducible builds would have prevented.

by aborsy

5/10/2026 at 1:54:01 PM

There have most likely been bugs or attacks that reproducible builds would have prevented.

Like what exactly?

by CyberDildonics

5/10/2026 at 10:17:26 AM

And you base it on what exactly ? It's "just" making sure the build process is always ordered.

If anything it will make attacker's job easier, as Ubuntu package will have same files structured exactly same way as Debian one.

by PunchyHamster

5/10/2026 at 3:37:56 PM

> as Ubuntu package will have same files structured exactly same way as Debian one.

As opposed to what? If Ubuntu uses the same source, of course they get the same binaries. And if Ubuntu applies patches, they'll get something different. And that's still true.

by yjftsjthsd-h

5/10/2026 at 2:00:34 PM

"mimimimi".

Those people do not care about quality in opensource at all. For longliving software this is very important.

Of course, all those javascript and kubernetes packages which are irrelevant in a few years again, might complain, but let them complain.

by deknos

5/10/2026 at 2:08:50 PM

> There was no bug or attack on Debian since 2007 that reproducible packages would prevent.

I'm reading this as a suggestion that the reproducible builds effort was an ineffective deterrent.

However, note that your observation could also be explained by the opposite: the reproducible builds effort was an effective deterrent, so nobody bothered with attempts.

> And it just ups the the contribution barrier to Debian higher

Until yesterday, the package just got flagged in the tracker, and you could either ignore it, or fix it yourself, or the kind people behind the reproducible builds effort supplied a patch themselves.

Now, you can no longer ignore it. But fixes are often trivial. Use a (stable) timestamp provided by the build, seed RNGs with some constant (instead of eg: time), etc. These are best practices anyway.

by ckastner

5/10/2026 at 3:19:15 PM

> However, note that your observation could also be explained by the opposite: the reproducible builds effort was an effective deterrent, so nobody bothered with attempts.

There was no attack that reproducible builds would help protect from before 2007 either.

> Until yesterday, the package just got flagged in the tracker, and you could either ignore it, or fix it yourself, or the kind people behind the reproducible builds effort supplied a patch themselves.

> Now, you can no longer ignore it. But fixes are often trivial. Use a (stable) timestamp provided by the build, seed RNGs with some constant (instead of eg: time), etc.

that's the entirety of the problem. App developers don't want to be package experts or build experts.

> These are best practices anyway.

They are not. They are best practices if you want reproducible builds. They are entirely useless waste of time if you don't care.

by PunchyHamster

5/10/2026 at 3:35:30 PM

> that's the entirety of the problem. App developers don't want to be package experts or build experts.

App developers and Debian package maintainers are already separate groups.

by yjftsjthsd-h

5/10/2026 at 4:15:55 PM

> They are not. They are best practices if you want reproducible builds.

Or if you're writing a test suite, and you want failing test results to be actionable.

Or you have any other type of behavior that you'd like to reproduce somehow.

One of the first things app developers ask for in bug/issue templates are the steps to reproduce something. I wonder why you'd think that they would suddenly be opposed to the concept when thinking of a build peocess.

by ckastner

5/10/2026 at 5:44:19 PM

> Or if you're writing a test suite, and you want failing test results to be actionable.

The class of bugs would be extremely small as the stuff that makes build hard to reproduce are 99% of the time stuff irrelevant to runtime like some build time embedded in binary, some file metadata having different timestamp, or maybe linker putting stuff in a bit different order.

> One of the first things app developers ask for in bug/issue templates are the steps to reproduce something. I wonder why you'd think that they would suddenly be opposed to the concept when thinking of a build peocess.

I think you will find amount of people that had problems reproducing because of non-100% exact build is vanishingly small, possibly non-existent.

And that is because if you get package version and want to reproduce it, you get the package, install it and try to reproduce it. The package WILL be 100% the same as the one you got in bug report because you both downloaded the same artifact from same mirror network. You don't need reproducibility to get same binary to reproduce bug

by PunchyHamster

5/10/2026 at 3:12:25 PM

That’s a big logical fallacy, I’m not sure if that’s what you want to go with

by Atotalnoob

5/10/2026 at 9:08:10 AM

https://wiki.debian.org/ReproducibleBuilds has some more infos; some is outdated, but it also has a chart showing how many packages are built in the CI, and how many of those are reproducible builds.

(Orange = FTBR = "failed to build reproducibly")

I'm not good at reading numbers from charts, but I'd guess it's a few percent (4-5ish?).

by perlgeek

5/10/2026 at 10:07:22 AM

all I get is this:

> Forbidden

> <p>You are not allowed to access this!</p>

(yes, with HTML tags on display) :)

EDIT: I also found a "I Challenge Thee" page in history. did I just get blocked by antibot measures? why???

by bpavuk

5/10/2026 at 10:46:28 AM

Do you have JavaScript disabled? They put one of those anti-scraper things on it.

by unleaded

5/10/2026 at 11:42:39 AM

nope, it's enabled. I can pass Cloudflare, reCaptcha, whatever Microsoft is doing, and Annubis, but Debian caught me off-guard

by bpavuk

5/10/2026 at 12:55:20 PM

What people really don't understand about reproducible builds is that they're not a guarantee that there's no backdoor.

They're a guarantee that if there's a backdoor, it's reproducible 100% of the time.

This is a godsend for white hats fighting the good fight.

And, as a side note, it's strongarming vs the bad guys: "Would be too bad if we could reproduce your shiny exploit 100% of the time wouldn't it!?".

Note that we should go further (but it's a bit orthogonal to reproducible builds): builds of the final binary/package should happen by first entirely discarding all files not necessary for the final build (like all test cases and all test assets). The build should literally happen in an environment that gets rid of those (after, of course, having test in another environment that all tests cases succeed): if I'm not mistaken get rid of test assets would have stopped Jia Tan's XZ backdoor attempt dead in its track (for example). Because IIRC there were binary data part of the backdoor hidden in some asset only used by test cases.

P.S: as a bonus they also allow to detect bit-flips (I'm not saying there aren't other ways to detect bit-flips: what I'm saying is that if you have deterministic builds anyway and something doesn't reproduce correctly due to a flipped-bit, it's going to be noticed).

by TacticalCoder

5/10/2026 at 4:46:12 PM

[dead]

by sieabahlpark

5/10/2026 at 7:28:17 AM

Good thing. NetBSD has fully reproductible build since 2017. https://blog.netbsd.org/tnf/entry/netbsd_fully_reproducible_...

by jaypatelani

5/10/2026 at 7:58:51 AM

As pointed in your link, NetBSD achieved this with some help from Debian. If I understand correctly, it's not that NetBSD tried harder, it's that their problem was easier: fewer packages which change less (they still use CVS, "stability" is an understatement!).

BTW, most Debian packages have reproducible builds. Those which have not (I'd say 5%) are shown in orange in the graph there: https://wiki.debian.org/ReproducibleBuilds

by idoubtit

5/10/2026 at 9:55:32 AM

Also, the *BSD are structured somewhat differently to a Linux distro.

It's not like the Linux world where you have distinct projects like the Kernel, GNU, OpenSSL, and then it's the distributions job to assemble everything.

In the BSD projects, the scope is developing and distributing an entire base system, i.e., the kernel but also the libc, the shell/all posix utilities, and a few third parties like OpenSSH (which are usually "softforked").

It's quite visible in the sources, it's a lot more than just a kernel: https://github.com/NetBSD/src

Additional packages you could get from pkg_in/pkgsrc (NetBSD), pkg-ng/ports (FreeBSD) or pkg_add (OpenBSD) are clearly distinct from the base system, installed in a dedicated subtree (/usr/src in NetBSD, /usr/local/ OpenBSD/FreeBSD), and provided in a best effort manner.

The reproducible build target was almost certainly only for the base system, which is a few percent of what Debian tries to achieve, and on which NetBSD has a tighter control over (developer + distributor instead of downstream assembler+distributor).

A reproducible base system is useful, but given how quickly you typically need to install packages from pkgsrc, it's not quite enough.

by kakwa_

5/10/2026 at 2:44:30 PM

> it's not that NetBSD tried harder, it's that their problem was easier: fewer packages which change less

Maybe that's trying harder on design rather than trying to remedy the consequences later.

by mmooss

5/10/2026 at 9:53:32 AM

While we are bragging, stagex was the first to hit 100% full source bootstrapped deterministic and hermetic builds last year and the first to make multiple signed reproductions by different maintainers on their own hardware mandatory for every release.

Debian has come along way, but when Debian says reproducible they mean they grab third party binaries to build theirs. When we say reproducible we mean 100% bootstrapped from source code all the way through the entire software supply chain.

We think that distinction matters.

https://stagex.tools

by lrvick

5/10/2026 at 2:04:06 PM

newcomers will always have it much easier. also guix i think also reached this.

also, stagex and others probably profited QUITE A LOT from the debian efforts, because they started to go upstream and talking to developers..

just arch linux profited from debian maintainers a decade before that an debian people asking upstream to improve...

by deknos

5/11/2026 at 4:41:09 PM

Guix did a full source bootstrap first, credit where well due, but it does not apply to their whole tree. E.g haskell is bootstrapped with a binary, qemu includes binary firmware blobs, etc.

Guix is not fully bootstrapped or reproducible.

To your point though, the incomplete efforts of many other distros absolutely accelerated us.

by lrvick

5/12/2026 at 10:19:27 AM

that depends though, which channel you choose. And their efforts for stage0 and such also increased the possibility for all.

Yay for Free software and Opensource! we all benefit! :)

by deknos

5/10/2026 at 1:09:39 PM

This!

Unfortunately, the term “reproducible” can be interpreted in many ways because there is no strict and complete definition. People and projects bend it to their liking.

Your approach is correct.

https://www.bootstrappable.org/

by nrvn

5/10/2026 at 10:20:18 AM

That distro has smaller codebase than Debian Installer.

by PunchyHamster

5/10/2026 at 10:16:51 PM

Stage -1: `hexdump`, `xxd`, or whatever you use to write files to your filesystem.

by matttttttttttt

5/10/2026 at 8:16:07 AM

A great milestone, congrats Debian on taking a stance and holding high standards for yourself, especially in the current era.

by Zopieux

5/10/2026 at 3:57:29 PM

I'm so happy to see this change. I got involved with reproducible builds in 2021 after reading in horror about the SolarWinds attack. [1]

I think Magnus Ihse Bursie said it best while working on reproducible builds of OpenJDK: "If you were to ask me, the fact that compilers and build tools ever started to produce non-deterministic output has been a bug from day one." [2]

[1] https://www.linux.com/news/preventing-supply-chain-attacks-l...

[2] https://github.com/openjdk/jdk/pull/9152#issue-1270543997

by jgneff

5/10/2026 at 10:22:11 AM

I wonder why this is a thing nowadays. I use yocto for embedded devices and it was almost a no-brainer to implement reproducible builds. I can also easily enable Debian package management, so everything is already available.

by micw

5/10/2026 at 11:06:28 AM

What do you mean why is it a thing nowadays?

Reproducible builds are an essential method in industrial computing - Debian isn’t at the forefront of this, it is merely adopting industry wide techniques also applied to other operating systems in use in long-term and safety-related applications.

Certainly, a lot of the hard work of the Yocto and Debian developers is already in your hands.

What is interesting is that this is now being applied in a more forward-focused policy by the Debian developers, that it will now be the norm rather than an option…

by MomsAVoxell

5/10/2026 at 3:19:20 PM

Did you actively verify that your builds were bit-reproducible?

by dezgeg

5/12/2026 at 4:37:38 AM

So these are broken on amd64. Debian arm64/forky rebuilderd stats https://reproduce.debian.net/arm64/stats/forky/

Most with failed to reproduce: NT_GNU_BUILD_ID. The others on some other bits. Mostly timestamps or hashes I assume

by rurban

5/10/2026 at 1:29:01 PM

amd64 forky

reproduced: 97.02% good: 17586 bad: 511 fail: 30 unknown: 0

This, statistics for other architectures, and the reasons for unreproducibility can be found at https://reproduce.debian.net.

by tofflos

5/10/2026 at 11:00:53 AM

I am always surprised Debian are leading this and not the commercial vendors. You'd think big organisations paying for RHEL and Ubuntu would be beating down the door for verifiable binaries.

by suprjami

5/10/2026 at 11:28:02 AM

If a competitor can prove that their packages are bit-for-bit identical to what a big organization is shipping, that allows the competitor to benefit from the security assurances of the big org. This is great for software freedom, not so great for wannabe monopolists.

by tremon

5/10/2026 at 11:52:07 AM

Reproducible builds exist to reduce the need for trust, while commercial vendors are in the business of selling trust.

by jorams

5/10/2026 at 11:40:07 PM

This fights against "opensource-washing" which is the practice of large companies claiming to release open source code, but the compile takes so long (as well as being overly-convoluted) that most people and many distros can't afford to maintain the package.

It feels like AI and traditional software are converging in complexity.

by casey2

5/10/2026 at 8:34:24 AM

Forbidden

You don't have permission to access this resource. Apache Server at lists.debian.org Port 443

:/

by pixel_popping

5/10/2026 at 9:41:59 AM

I can see it just fine; maybe an overzealous firewall thinks you're a bot? At any rate, the Wayback Machine has it: https://web.archive.org/web/20260510074120/https://lists.deb...

by ameliaquining

5/10/2026 at 11:22:19 AM

Unfortunately, many of these "protections" don't know what is a bot or a human. Many clueless websites are often just blocking huge swaths of legitimate readers and customers.

by baranul

5/10/2026 at 2:38:27 PM

Why would you block access to a static page, even Bots, what's the point? I'm not a bot, very typical non-privacy setup (Firefox, Linux, VPN) for personal usage.

It does work with my privacy/scrapping setup (residential proxy, spoofed fingerprints, Qubes and so on), great job debian.

by pixel_popping

5/10/2026 at 8:26:07 AM

Has anyone fought Microsoft Visual Studio successfully to produce reproducible builds of C++ programs? From what I have heard, it is one of the worst contexts to do it.

by inglor_cz

5/10/2026 at 2:45:21 PM

It's that RICH header that you need to exclude. I just tested my copy of MSVC 2019, and `/emittoolversioninfo:no` will exclude the RICH header from the binary. Supposedly also works in MSVC 2022.

The build timestamps in the PE header and export table are also a problem as well.

by Dwedit

5/10/2026 at 10:31:51 AM

Probably easiest way is to use Bazel to leverage the effort that has gone in there

by azkalam

5/10/2026 at 11:01:03 AM

Well, you can't build MSVS yourself, reproducibly or otherwise, so this is a less appealing endeavor I would think.

by einpoklum

5/10/2026 at 2:48:46 PM

”Optimize the code for 5 seconds”, as many compilers, including vc++ on windows did, was probably one of the dumbest thing ever invented. It meant that the binaries became more optimized when building on faster computers.

by kkyktkrkekk

5/10/2026 at 6:53:33 AM

A small step for debian,

giant leap for mankind.

by shevy-java

5/10/2026 at 7:17:19 AM

As someone who recently spent a lot of time on making a large C++ program entirely reproducible on 4 different OS’es, one cannot understate just how many tiny details matter here.

by stingraycharles

5/10/2026 at 9:41:14 AM

"overstate"

by gjvc

5/10/2026 at 10:36:49 AM

Whoops, yes. Well I hope the point came across anyway.

by stingraycharles

5/10/2026 at 11:11:46 AM

it's funny that as a non-native speaker, I have to check with Gemini about how "cannot overstate" is used

I also asked Gemini whether we express ourselves that way in my mother tongue (Mandarin), and yes, we do, but it came off as being too formal way of speaking. We don't normally use it (I'm not from China/Taiwan though)

by cyh555

5/10/2026 at 4:49:13 PM

... and most of this work is done by other distros and maintainers. Starting with binutils

by rurban

5/10/2026 at 2:07:00 PM

That's cool but I'm honestly a bit disappointed in how apt refused to embrace/support both the container and AI/GPU aspects of computing. Are we going to see some changes there?

by amelius

5/10/2026 at 2:54:43 PM

Those seem like unrelated things? I can imagine ways for apt to integrate with containers, but what would it possibly do for AI or GPU other than delivering packages like it already does?

by yjftsjthsd-h

5/10/2026 at 4:40:39 PM

What exactly are you talking about? Those don't seem related.

by Arrowmaster

5/10/2026 at 9:44:14 AM

[dead]

by idovmamane

5/10/2026 at 12:40:04 PM

[flagged]

by peterhadlaw

5/10/2026 at 11:15:48 AM

Why the fuck does that site break the back button? DO NOT do that.

by Hendrikto

5/10/2026 at 1:04:29 PM

since there is no other way to reach you please allow me to use this off topic message to let you know that there is a response to your comments on the gnupg discussion from two weeks ago.

by em-bee

5/10/2026 at 10:57:57 AM

Debian must ship packages without the hard dependence on systemd.

by einpoklum

5/10/2026 at 6:17:33 AM

zero improvement on end-user experience. does not solve supply chain issues, debian package will reproducabily contain the malware from upstream.

by blueflow

5/10/2026 at 6:45:46 AM

> zero improvement on end-user experience.

Maybe not by itself, but it does allow for the ecosystem to be audited, in a way that ultimately benefits the end-user. It really is an important part of a healthy supply chain.

by quantummagic

5/10/2026 at 10:11:40 AM

no problem in Debian since the start of the effort would be solved by reproductible builds

This is nice pat yourself on the back achievement for people that prefer security theatre and checking boxes than doing something actually useful, and they wasted thousands man hours of poor victims that had to implement it

by PunchyHamster

5/10/2026 at 7:27:25 AM

[flagged]

by miohtama

5/10/2026 at 9:43:09 AM

NK isn't the hostile superpower I'm most concerned about.

by LtWorf

5/10/2026 at 8:05:50 AM

While taking no stance on your statement, I think “fewer” works better in this context than “less”.

by testdelacc1

5/10/2026 at 9:42:10 AM

"fewer" when the measure is discrete, "less" when it is continuous

by gjvc

5/10/2026 at 6:51:14 AM

That's not what reproducible builds aim to prevent, and no one claims that. When upstream pushes bad code, that's on upstream.

The thing reproducible builds aim to prevent is Debian or individual developers and system administrators with access rights to binary uploads and signing keys to get forced to sign and upload binary packages by attackers - be these governments (with or without court orders) or criminal organizations.

As of now, say if I were an administrator of Debian's CI infrastructure, technically there would be nothing preventing me from running an "extra" job on the CI infrastructure building a package for openssh with a knock-knock backdoor, properly signing it and uploading it to the repository. For someone to spot the attack and differentiate it, they'd have to notice that there is a package in the repository that has no corresponding build logs or has issues otherwise.

But with reproducible builds, anyone can set up infrastructure to rebuild Debian packages from source automatically and if there is a mismatch with what is on Debian's repository, raise alarm bells.

by mschuster91

5/10/2026 at 8:25:44 AM

Reproducible builds shows that, within a specific configuration, the code produced the binary, regardless of who signed or published it.

Indeed, this could mitigate an attacker replacing the binary with something that's not produced from the code, but it does not mitigate the tool chain or code itself containing the exploit, creating a malicious binary.

by ownagefool

5/10/2026 at 6:23:05 AM

Debian has had a better "software supply chain" posture than any other player in the ecosystem since before the turn of the century. While we all face the risk of malware from upstream, Debian is the least at risk of being affected by it. See for example the stream of issues from npm et al. None of it has affected Debian.

by rlpb

5/10/2026 at 11:32:27 AM

You do remember the xz-utils backdoor was found in Sid right?

https://en.wikipedia.org/wiki/XZ_Utils_backdoor

by suprjami

5/10/2026 at 2:55:42 PM

It would have been found in a whole lot more places if it hadn't been for that meddling Microsoft employee.

by Dwedit

5/10/2026 at 6:26:33 AM

> for example the stream of issues from npm et al.

Curious, what distros where affected by npm supply chain attacks?

by alkindiffie

5/10/2026 at 8:25:07 AM

It's npm that's affected, therefore it's not even considered when choosing language/ecosystem for writing distro tools. You'll find no sane distro writing package manager in javascript precisely to avoid this joke of a supply chain.

by throw_a_grenade

5/10/2026 at 11:50:20 AM

I quite like the OpenBSD approach to Go and Rust projects in ports. They store all the dependencies and their hashes in the build recipe, not trusting the project ones. And they’re more readable.

Here is jujutsu’s list of dependencies[0] and their hashes[1]. As an aside, that’s why I don’t like those packages managers. Something like Python’s numpy or lib curl, get sliced into atomic portions.

[0]: https://github.com/openbsd/ports/blob/master/devel/jujutsu/c...

[1]: https://github.com/openbsd/ports/blob/master/devel/jujutsu/d...

by skydhash

5/10/2026 at 12:14:16 PM

ECMA-262 doesn't require the use of NPM or NodeJS. (In fact, they are at odds, even 10+ years after modules were standardized in ES6.)

by cxr

5/10/2026 at 6:33:37 AM

It does not solve all supply chain issues, it do solve some supply chain issues.

Not being able to see if the source code shipped is the same as been used for creating the binary is scary

by iveqy

5/10/2026 at 7:51:01 AM

Has there been a single publicly known attack that would have been prevented by this?

by murderfs

5/10/2026 at 11:13:56 AM

Why should it only be valuable if the effects were to be publicly known?

There are plenty of places in industrial computing where reproducible builds have prevented subterfuge within the organizations themselves. Injecting binaries to do inf-/exfiltration is a long-standing industrial espionage activity which is of immense value to all users of the operating system - not just the consumer users.

by MomsAVoxell

5/10/2026 at 12:47:49 PM

My magic beans have prevented thousands of tiger attacks in top secret underground moon bases, never you mind that there's no way for me to actually prove this.

There's a certain irony in pushing for verifiable builds with completely unverifiable claims.

I've worked at several of the biggest targets for espionage, industrial or otherwise, and to the best of my knowledge, the only thing that's ever been discovered by their reproducible build efforts has been failing hardware on build reproducers

by murderfs

5/11/2026 at 6:11:44 AM

You probably don’t have enough experience with professional enterprise IT departments. Rootfs audits are a thing made a lot easier, and more effective, with reproducible builds.

by MomsAVoxell

5/10/2026 at 10:13:37 AM

Zero in Debian. They have enough other procedures to catch it.

Less diligent projects had it but there are easier ways to fix it

by PunchyHamster

5/10/2026 at 9:44:22 AM

Several actually. Pypi is regularly targeted in this way.

by LtWorf

5/10/2026 at 10:33:51 AM

But how many of those attackers also had the ability to publish a github commit but didn't to remain more stealthy.

by charcircuit

5/10/2026 at 12:11:22 PM

This question is meaningless. Attackers will pick the best attack if they have more at their disposal. The fact that they didn't push a commit shows it's better not to. So closing that attack is good.

by LtWorf

5/10/2026 at 11:42:30 PM

There is meaning. The difference in detection time does have meaning. If the improvement of detection time was marginal there may have been a different project time could have been invested in to make it even faster to catch such things than reproducible builds.

by charcircuit

5/10/2026 at 10:12:51 AM

Hasn't happened in Debian

by PunchyHamster

5/10/2026 at 11:15:17 AM

“Hasn’t happened” is quite naive. It happens internally - putting unscrupulous code in a company’s distro before torching the place is a surprisingly regular occurrence in places which have long since adopted Debian as a platform host. IT departments around the globe will benefit from this immensely.

by MomsAVoxell

5/10/2026 at 4:59:48 PM

And reproducible builds do not prevent that.

The one single fail point they prevent is infected build hosts.

That might be some reasonable benefit for the company if it is building it on public architecture, but for projects like Debian that insist build hosts are basically offline (package in, package out with no internet access during build process) it is very fringe benefit.

by PunchyHamster

5/11/2026 at 6:10:28 AM

Nonsense, of course reproducible builds can be used by IT departments to catch nefarious behavior - they regularly do.

by MomsAVoxell

5/10/2026 at 6:56:16 AM

This is some of the best news I've heard recently when it comes to figuring out how to produce high quality Software Bills of Materials for the upcoming EU Cyber Resilience Act, for what it's worth. Reproducible packages are actually worth a great deal when you are selling products with digital elements. Much easier to scan through, audit, etc. with confidence.

by hiAndrewQuinn

5/10/2026 at 7:20:13 AM

If you find yourself holding opinions of the kind: "If it can't be made perfect, it shouldn't be changed at all?" you may want to consider that most things that work well today were incrementally improved.

Reproducable builds are not solving all issues as you rightly observed, but they can be a stepping stone (or even a pre-condition) for further measures.

by atoav

5/10/2026 at 6:55:03 AM

Well - reproducible also means code guarantee. It may not improve an end-user experience directly, but you get an extra quality control step, as guarantee, here. I think reproducibility is great. If we can achieve that, it should be achieved. See also NixOS; it can guarantee that snapshot xyz works, not just for one user, but ALL users. I see it as hopping from guarantee to guarantee. That's actually a good thing in the long run. Just think differently here.

by shevy-java

5/10/2026 at 10:05:56 AM

> zero improvement on end-user experience

The end-user experience is that now you can host your Debian binaries in caches and CDNs without worrying about supply chain hackers.

You can verify that file hashes match the ones on Debian's website and sleep much better at night.

If you don't trust Debian's website then you can rebuild yourself and check if Debian has been compromised.

by otabdeveloper4

5/10/2026 at 11:34:49 AM

You could already do that since Debian cryptographically signs all its package indexes, and the indexes contain the hash of all packages. The additional guarantee that reproducible builds bring is that you can re-build the packages in your own controlled environment and verify that the resulting package is bit-for-bit identical to what Debian offers.

by tremon

5/11/2026 at 5:50:36 PM

Cryptographic signatures only protect against MitM (something extremely rare in the real world) and do nothing against compromised Debian infrastructure and supply chains (the real attack vector 99% of the time).

Reproducible builds protect against all attacks.

by otabdeveloper4

5/12/2026 at 1:28:27 PM

> Reproducible builds protect against all attacks.

Generic statements like this are always false. As a simple rebuttal, reproducible builds do not protect against source-level attacks such as intentional backdoors or disabled/obfuscated access checks. In fact, I'd say that reproducible builds protect against one class of attacks only: compromise of the build infrastructure.

by tremon

5/10/2026 at 11:10:34 AM

Who is this mythical end user? Reproducible builds are good for everyone - not just the average joe.

by MomsAVoxell

5/10/2026 at 9:56:21 AM

So much time has been wasted on reproducible builds which could have better spent on securing more important parts of Debian. Practically minor changes like a build timestamp being different is not an issue.

by charcircuit

5/10/2026 at 11:27:25 AM

It allows verifying that the binaries actually match the source, which is extremely valuable.

by Hendrikto

5/10/2026 at 4:14:48 PM

Bit for bit matching is not required for that.

by charcircuit

5/11/2026 at 1:55:26 PM

It makes it much simpler and more robust though. Also, it allows for content addressing a la Nix, among other benefits.

by Hendrikto

5/11/2026 at 6:57:17 PM

I reject that those benefits are actually that useful compared to the effort needed to do so.

You can content addressing without reproducible builds. You just have a canonical version, which typically is built by the application developer.

by charcircuit

5/10/2026 at 12:15:18 PM

Yes, making sure build timestamps are reproducible isn't a security win.

What is a win is that two independent parties can run the same build, and get the same binaries.

This is important because it removes trust from builders: anyone can verify their output.

It just so happens that unimportant things like build versions impede that.

by farfatched

5/10/2026 at 4:15:59 PM

Anyone can verify the actual code in the binary matches even if some bytes within the binary file itself are different. The verification routine doesn't have to be a basic bit for bit equality test.

by charcircuit

5/11/2026 at 8:39:33 AM

For sure.

This has been the status quo in Debian for a while now. You can build, and use diffoscope to audit the differences.

It's a stronger security property to have bit-for-bit reproducibilty, and it looks like Debian are ready to commit to it.

by farfatched

5/11/2026 at 6:57:24 PM

You are just restating the point of the thread and not addressing the low return on investment doing this is.

by charcircuit

5/12/2026 at 4:17:29 AM

Fair point.

I had figured the cost would decrease in time as deterministic builds became the norm (i.e. build tools stop including build timestamps).

I agree that it might not have positive POI. Bit tricky for me to judge.

by farfatched

5/10/2026 at 2:17:41 PM

you are free to provide patches instead of bitching.

by deknos

5/10/2026 at 4:17:40 PM

And Debian is able to offer me a few million dollars yearly to help fix their security situation.

by charcircuit

5/11/2026 at 5:45:49 AM

the idea that debian has a few million dollars to spare creates the assumption, that even if they would have... you would either not know how to fix issues, or not worth it.

by deknos

5/10/2026 at 7:43:33 AM

Debian, like any other legacy distro, mush became declarative, because the '80s model of manual deploy and the absurd pain of D/I and Preseed must end.

by kkfx

5/10/2026 at 10:08:09 AM

In the end, Nix is just a thin veneer on this stuff.

Given how many quick & dirty sed patching or exec commands I've seen in the few nix package/modules I've read, I would not exactly bet my life on it being completely idempotent & reproducible.

by kakwa_

5/10/2026 at 10:07:16 PM

it's the best option after IllumOS (OpenSolaris) IPS integrated with ZFS. Far less powerful not imposing zfs (only well supported for root, swap, encryption etc), so not integrated in the package system and bootloader management (BEs, Boot Environments).

It's not reproducible bit by bit, it fetch the current version of anything, but it's still easy to reproduce enough, stable enough and complete enough, while classic distros need a fresh install every major release or facing issues an keeping a system in unknown state for long until it explode.

by kkfx

5/10/2026 at 12:16:51 PM

I've been 100% on NixOS on many years, but it's Debian that really drove this project.

They're still a pragmatic choice for many usecases.

by farfatched