Counterfeiting of valuable documents is an increasingly serious problem. Banknotes, drivers licenses, passports, diplomas and stock certiﬁcates are all the subjects of increasingly frequent and accurate counterfeiting efforts. This is in part due to the performance improvements of consumer inkjet printers. Design features which required great labor and skill to reproduce on an engraved-plate printing process pose essentially no difﬁculty to a counterfeiter armed with an accurate scanner and high-resolution color printer. We show how simple changes in banknote design coupled with possible changes in rendering engines can make the task of counterfeiting enormously more difﬁcult.