Lacida
Encyclopedia
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
rotor cipher machine
Rotor machine
In cryptography, a rotor machine is an electro-mechanical device used for encrypting and decrypting secret messages. Rotor machines were the cryptographic state-of-the-art for a prominent period of history; they were in widespread use in the 1920s–1970s...
. It was designed and produced before World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
by Poland
Poland
Poland , officially the Republic of Poland , is a country in Central Europe bordered by Germany to the west; the Czech Republic and Slovakia to the south; Ukraine, Belarus and Lithuania to the east; and the Baltic Sea and Kaliningrad Oblast, a Russian exclave, to the north...
's Cipher Bureau
Biuro Szyfrów
The Biuro Szyfrów was the interwar Polish General Staff's agency charged with both cryptography and cryptology ....
for prospective wartime use by Polish military higher commands.
History
The machine's name derived from the surnameSurname
A surname is a name added to a given name and is part of a personal name. In many cases, a surname is a family name. Many dictionaries define "surname" as a synonym of "family name"...
initials of Gwido Langer
Gwido Langer
Lt. Col. Karol Gwido Langer was chief of the Polish General Staff's Cipher Bureau from at least mid-1931.-Life:...
, Maksymilian Ciężki
Maksymilian Ciezki
Maksymilian Ciężki was the head of the German section of the Polish Cipher Bureau in the 1930s, during which time the Bureau decrypted German Enigma messages....
and Ludomir Danilewicz
Ludomir Danilewicz
Ludomir Danilewicz was a Polish engineer and, for some ten years before the outbreak of World War II, one of the four directors of the AVA Radio Company in Warsaw, Poland...
and / or his younger brother, Leonard Danilewicz
Leonard Danilewicz
Leonard Stanisław Danilewicz was a Polish engineer and, for some ten years before the outbreak of World War II, one of the four directors of the AVA Radio Company in Warsaw, Poland...
. It was built in Warsaw
Warsaw
Warsaw is the capital and largest city of Poland. It is located on the Vistula River, roughly from the Baltic Sea and from the Carpathian Mountains. Its population in 2010 was estimated at 1,716,855 residents with a greater metropolitan area of 2,631,902 residents, making Warsaw the 10th most...
, to the Cipher Bureau's specifications, by the AVA Radio Company
AVA Radio Company
The AVA Radio Company was a Polish electronics firm founded in 1929 in Warsaw, Poland. AVA designed and built radio equipment for the Polish General Staff's Cipher Bureau, which was responsible for the radio communications of the General Staff's Oddział II .After the Cipher Bureau's...
.
In anticipation of war, prior to the September 1939 invasion of Poland
Invasion of Poland (1939)
The Invasion of Poland, also known as the September Campaign or 1939 Defensive War in Poland and the Poland Campaign in Germany, was an invasion of Poland by Germany, the Soviet Union, and a small Slovak contingent that marked the start of World War II in Europe...
, two LCDs were sent to France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
. From spring 1941, an LCD was used by the Polish Team Z at the Polish-, Spanish- and French-manned Cadix
Cadix
Cadix was the codename of a World War II clandestine Polish-French intelligence center that operated at Uzès, on the Mediterranean coast in southern, Vichy France, for over two years from September 1940 to November 9, 1942.-History:...
radio-intelligence and decryption center at Uzès
Uzès
Uzès is a commune in the Gard department in southern France.It lies about 25 km north-northeast of Nîmes.-History:Originally Ucetia, Uzès was a small Gallo-Roman oppidum, or administrative settlement. The town lies at the source of the Eure, from where a Roman aqueduct was built in the first...
, near France's Mediterranean coast.
Prior to the machine's production, it had never been subjected to rigorous decryption attempts. Now it was decided to remedy this oversight. In early July 1941, Polish cryptologists Marian Rejewski
Marian Rejewski
Marian Adam Rejewski was a Polish mathematician and cryptologist who in 1932 solved the plugboard-equipped Enigma machine, the main cipher device used by Germany...
and Henryk Zygalski
Henryk Zygalski
Henryk Zygalski was a Polish mathematician and cryptologist who worked at breaking German Enigma ciphers before and during World War II.-Life:...
received LCD-enciphered messages that had earlier been transmitted to the staff of the Polish Commander-in-Chief, based in London. Breaking the first message, given to the two cryptologists on July 3, took them only a couple of hours. Further tests yielded similar results. Colonel Langer
Gwido Langer
Lt. Col. Karol Gwido Langer was chief of the Polish General Staff's Cipher Bureau from at least mid-1931.-Life:...
suspended the use of LCD at Cadix.
In 1974, Rejewski explained that the LCD had two serious flaws. It lacked a commutator
Commutator
In mathematics, the commutator gives an indication of the extent to which a certain binary operation fails to be commutative. There are different definitions used in group theory and ring theory.-Group theory:...
("plugboard"), which was one of the strong points of the German military Enigma machine
Enigma machine
An Enigma machine is any of a family of related electro-mechanical rotor cipher machines used for the encryption and decryption of secret messages. Enigma was invented by German engineer Arthur Scherbius at the end of World War I...
. The LCD's other weakness involved the reflector
Reflector (cipher machine)
A reflector, in cryptology, is a component of some rotor cipher machines, such as the Enigma machine, that sends electrical impulses that have reached it from the machine's rotors, back in reverse order through those rotors.- Other names :...
and wiring. These shortcomings did not imply that the LCD, somewhat larger than the Enigma and more complicated (e.g., it had a switch for resetting to deciphering), was easy to solve. Indeed, the likelihood of its being broken by the German E-Dienst was judged slight. Theoretically it did exist, however.