one algorithm, its own package, an audited provenance

Before an algorithm can be trusted it has to be inspectable in isolation. Ours arrived tangled into a larger system: key generation, signing and the arithmetic underneath all moved together, and a defect anywhere looked like a defect everywhere.

The decision was to extract exactly one algorithm into its own small package with no dependency on the application — its own parameter set, its own test vectors, its own build posture, including a build that refuses the operating system's standard library and fixes its allocation discipline. Nothing from the application could leak in, and nothing leaked out except a deliberately small surface.

The part that mattered most happened before any code: a provenance audit of the external sources the work would touch. Eight were surveyed. Four could be reused under permissive terms and were brought in one component at a time with the mapping recorded. Three carried no license at all, so they were demoted to algorithm reference only — read and not copied, with the behaviour re-derived from the published description. The eighth was a paper.

That audit is why the package can be shown to anyone. Every line has a recorded origin or was written here, and the parameter choices come from the published specification rather than from tuning until the tests went green.

The cost is that importing arithmetic primitives is tedious and the constraint list is long. The benefit is that the most consequential code in the product is the part a reviewer can read end to end in an afternoon.