davide
4e3d93e167
With proof of work skipped, chaining headers from a checkpoint up to a transaction's block proves nothing: a server can fabricate a header and fake headers after a real checkpoint. The header must now hash-chain up to the nearest checkpoint at or above its height, whose hash is hardcoded. This also anchors heights below the first checkpoint. The cached anchor state is renamed AnchoredDownTo and caches without it are re-verified once. Blocks above the newest checkpoint remain a documented limit. See ADR 0040.