Dorotheum has unveiled an Enigma encryption device produced in 1944, used in World War II by the German military, to be sold at the Vienna-based auction house on June 4 with an estimate of €30,000–€40,000.

Invented by German engineer Arthur Scherbius around 1918, Enigma was first introduced to German military use in 1926. Believed to be indecipherable by enemies, the machine became a crucial tool for the army in the later 1920s to 1930s. It was placed under restricted production for military and state use before the start of the war.

During WWII, at London’s Bletchley Park, a team of army cryptographers under the direction of famed British mathematician Allan Turing deciphered Nazi Enigma radio messages. The codebreaking team’s interception was crucial to Allied success and played a central role in the “Ultra” mission used to trace German submarines. The Enigma encryption interception did not come to public light until decades after the war, in the 1970s.

The storied wartime device is a rarity in the secondary market, with an estimated 20,000 editions made in the pre- and inter-war period. About 50 remain in private and institutional collections. The highest price paid for an original Enigma model includes one sold at Christie’s in June 2017 for $547,500.