December 21st 2020

Interview: Reproducibility and the future of free software

Irecently took part in an interview with Vladimir Bejdo, an intern at the Software Freedom Conservancy, in order to talk about the Reproducible Builds project, my own participation in software freedom, the importance of reproducibility in software development and to have a brief discussion on the issues facing free software as a whole:

VB: To start off with, it might be useful to first ask you this – how would you relate the importance of reproducibility to a user who is non-technical?

CL: I sometimes use the analogy of the food ‘supply chain’ to quickly relate our work to non-technical audiences. The multiple stages of how our food reaches our plates today (such as seeding, harvesting, picking, transportation, packaging, etc.) can loosely translate to how software actually ends up on our computers, particularly in the way that if any of the steps in the multi-stage food supply chain has an issue then it quickly becomes a serious problem.

For example, even if we could guarantee that only the most wholesome apples were picked in our orchards, if they became tainted on the way to the supermarket it will be a real problem for us at the end of the day. We may not even be able to even tell by simply inspecting our Pink Ladies or Honeycrisps, and washing them thoroughly under the tap may not be enough either.

In an ideal world, we would be able to personally inspect the provenance of our food at all of the stages of manufacturing and transportation. But at some point, we must place our trust in the process and in brands, as well as various regulatory bodies to ensure that potential problems in our food are minimized, possibly even paying a time/effort premium by growing our own or buying direct from local markets in order to minimize the number of steps, etc.

However, when we use free software we can do better: ‘Reproducible builds’ are a set of software development practices, ideas and tools that create an independently-verifiable path all the way from the original source code to what actually runs on our machines. Reproducible builds can reveal the injection of back-doors introduced by the hacking of developers’ own computers, build servers and package repositories, and also expose where volunteers or companies have been coerced into making changes via blackmail, court order, and so on.

With reproducible builds, there is no longer any need to trust any particular source of authority. In the same way that, say, a Mr Smith might check that his calculator is giving him the right answer to “2+2=4” by asking enough of his friends to check theirs too, users and developers of a reproducible build can verify the software they are using by creating a collective consensus instead.

The full interview can be found on the Conservancy webpages.