What a certificate is actually for

There is a temptation, in this trade, to design for the adversary. It produces documents dense with features that only a laboratory can read, and it is usually the wrong instinct.

The realistic examination of a diploma is a hiring manager glancing at a framed sheet on a wall. The realistic examination of a ticket is a steward at a gate at dusk. The realistic examination of a provenance seal is a curator forty years after the seal was applied, who has never seen one before and has nothing to compare it with.

Designing for thirty seconds

That reality suggests a hierarchy. The first feature should require nothing: no lamp, no loupe, no training. Hold it to the light; tilt it; touch it. The second should require one cheap thing that the checking institution can own — an ultraviolet lamp on a desk. Only the third should require a laboratory, and it should be there to settle disputes rather than to prevent them.

A document built that way is harder to specify and easier to check, which is the correct direction for the difficulty to run.