The TgS-1 DUDEK (Polish: hoopoe) (Dalekopisowe Urz?dzenie Do Elektronicznego Kodowania -- Teleprinter Device for Electronic Coding) was an on-line and off-line encryption system developed during the Cold War in the 1960s in communist Poland by the Telkom Teletra company and the Ministry of Interior for use on teleprinter circuits. The units saw use in the Polish Ministerstwo Spraw Wewn?trznych networks serving the (Milicja Obywatelska), the (S?u?ba Bezpieczeństwa), the Polish Ministry of National Defense (Ministerstwo Obrony Narodowej), the Ministry of Foreign Affairs (Ministerstwo Spraw Zagranicznych) and the National Bank of Poland (Narodowy Bank Polski).