Name: No Snake Oil: Verifying Python Package Builds - Jens Dietrich, Victoria University of Wellington
Start: 2026-10-06T14:17:00+0200
End: 2026-10-06T14:35:00+0200

No Snake Oil: Verifying Python Package Builds - Jens Dietrich, Victoria University of Wellington

Tuesday October 6, 2026 14:17 - 14:35 CEST

South Hall 3A

Python has become the default language for interacting with AI, with packages being distributed through registries like the Python Package Index (PyPi). This creates a need to analyse supply chains comprising such packages. One such analysis is to rebuild packages in order to identify compromised builds injecting malware. Independent rebuilds in hardened environments have the added advantage that they can generate and record provenance in order to increase the trustworthiness of packages. Two tools that are designed to automate such rebuilds and run them at scale are macaron and oss-rebuild. We study 12,180 popular releases from pypi and find that the byte-for-byte equivalence rate is generally low. We analyse the reasons why they produce different wheels, and find that equivalence between the original and rebuilt wheels can often still be established, preserving most of the guarantees users expect from rebuildable releases. We present and evaluate daleq4py, a tool to establish the equivalence of Python wheels through the kernel of a normalisation function that is based on provenance-preserving datalog rules. Experimental results show that daleqpy substantially expands the set of rebuilds that can be accepted as equivalent. Although only 15.4% of macaron rebuilds and 19.1% of oss-rebuild rebuilds are byte-for-byte identical to the published PyPi wheels, daleq4py establishes wheel equivalence for 60.2% and 78.9% of source-equivalent rebuilds, respectively.

Speakers

Jens Dietrich

Victoria University of Wellington

Jens is an Associate Professor in the School of Engineering and Computer Science (ECS) at Victoria University of Wellington in Wellington, New Zealand. He has a Master in Mathematics and a PhD in Computer Science from the University of Leipzig in Germany. After graduating in 1996... Read More →

Tuesday October 6, 2026 14:17 - 14:35 CEST
South Hall 3A

SCORED Sessions, Supply Chain Ecosystems

OpenSSF Community Day Europe 2026

Jens Dietrich

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OpenSSF Community Day Europe 2026

Jens Dietrich

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