OFAC-sanctioned cryptocurrency address census and analysis code for the opacity frontier

Replication package for the paper on the opacity frontier in illicit-cryptocurrency detection. It contains a complete census of the cryptocurrency addresses carried by the U.S. Treasury OFAC Specially Designated Nationals (SDN) list — 963 addresses across 19 assets, held by 91 sanctioned entities, each joined to its entity and sanction programme — together with the derived measurement artifacts reported in the paper (actionability taxonomy, composition by sanction programme, on-chain value resolved for the sanctioned Bitcoin tier, source-verified OSINT migration timeline) and the code that produces both. Two inputs are deliberately not redistributed: the raw SDN advanced XML (retrievable from the primary OFAC endpoint; the SHA-256 of the snapshot used is recorded in the README) and the Elliptic dataset, which carries its own licence and is fetched from its public PyG mirror by the included script. Derived data are released under CC BY 4.0, code under the MIT licence. The address census derives from a public record of the U.S. government.