The Cipher Department of the High Command of the Wehrmacht was the Signal Intelligence Agency of the Supreme Command of the Armed Forces of the German Armed Forces before and during World War II. OKW/Chi, within the formal order of battle hierarchy OKW/WFsT/Ag WNV/Chi, dealt with the cryptanalysis and deciphering of enemy and neutral states' message traffic and security control of its own key processes and machinery, such as the rotor cipher ENIGMA machine. It was the successor to the former Chi bureau of the Reichswehr Ministry.

The Oberkommando der Wehrmacht was the supreme military command and control office of Nazi Germany during World War II. Created in 1938, the OKW replaced the Reich Ministry of War and had oversight over the individual high commands of the country's armed forces: the army, navy, and air force.