Enlarge /. The Enigma cipher machine found in the Baltic Sea lies on a table in front of the Schleswig-Holstein archaeological office. After its discovery, the machine was handed over to the office by research diver Huber. Photo: Axel Heimken / dpa (Photo by Axel Heimken / Image alliance via Getty Images)
Divers searching the Baltic Sea for discarded fishing nets have come across the rarest finds: an Enigma encryption machine that the Nazis used to encrypt secret messages during World War II.
The electromechanical device was used extensively by the Nazi military to encrypt communications that were typically transmitted by radio in Morse code. Three or more rotors on the device used a stream cipher to convert each letter of the alphabet to a different letter.
The puzzle looked like a typewriter. An operator would use the keys to enter plain text and the converted ciphertext would be reflected in 26 lights above the keys – one light for each letter converted. The converted letters would then be transcribed to derive the ciphertext.
The encryption keys were changed using a number of device settings that were changed periodically using lists that were made available in advance. People who received the messages had to use the same lists as the senders in order for the messages to be readable.
Divers on behalf of the environmental group WWF found the Enigma machine last month while searching for abandoned fishing nets in the bay of Gelting off the coast of Germany. As the picture above shows, the restored device was rusty and corroded, but individual keys with the letters they designate remain intact and clearly visible.
"A colleague swam up and said," There's a network with an old typewriter, "Florian Huber, the lead diver, told the DPA news agency. The team soon realized that the device was something much more remarkable.
"I have made many exciting and strange discoveries in the past 20 years. But I never thought that one day we would find one of the legendary Enigma machines," Huber told Reuters.
The diver suspects that the device was lost shortly before Germany's surrender in May 1945. At that time, the Nazi leaders issued orders to sink submarines in Gelting Bay to prevent their capture by the Allies.
The puzzle made it difficult for the Allies to track down German submarines until a British team led by mathematician and scientist Alan Turing broke the encryption of the device used. The feat, based on breakthroughs by scientists at the Polish encryption bureau, enabled the Allies to decipher messages about German military movements. Many historians attribute the achievement to shortening the war and preventing many thousands of deaths.
Experts from the State Archaeological Museum will restore the machine. The process, which will include extensive desalination, is expected to take around a year.
Updated post to add details about the Polish Cipher Bureau.