The Lacida, also called LCD, was a Polish

rotor cipher machine In cryptography, a rotor machine is an electro-mechanical stream cipher device used for encrypting and decrypting messages. Rotor machines were the cryptographic state-of-the-art for much of the 20th century; they were in widespread use in the 19 ...

. It was designed and produced before

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

by Poland's Cipher Bureau for prospective wartime use by Polish military higher commands.

History

The machine's name derived from the

surname In some cultures, a surname, family name, or last name is the portion of one's personal name that indicates one's family, tribe or community. Practices vary by culture. The family name may be placed at either the start of a person's full name ...

initials of Gwido ''La''nger, Maksymilian ''Ci''ężki and Ludomir ''Da''nilewicz and / or his younger brother, Leonard ''Da''nilewicz. It was built in

Warsaw Warsaw ( pl, Warszawa, ), officially the Capital City of Warsaw,, abbreviation: ''m.st. Warszawa'' is the capital and largest city of Poland. The metropolis stands on the River Vistula in east-central Poland, and its population is officia ...

, to the Cipher Bureau's specifications, by the

AVA Radio Company The AVA Radio Company (Polish: ''Wytwórnia Radiotechniczna AVA'') 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 ...

. In anticipation of war, before the September 1939

invasion of Poland The invasion of Poland (1 September – 6 October 1939) was a joint attack on the Republic of Poland by Nazi Germany and the Soviet Union which marked the beginning of World War II. The German invasion began on 1 September 1939, one week aft ...

, two LCDs were sent to

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

. From spring 1941, an LCD was used by the Polish ''Team Z'' at the Polish-, Spanish- and French-manned

Cadix ''Cadix'' was a World War II clandestine intelligence center at Uzès, in southern France, from September 1940 to 9 November 1942. During this period southern France was under the control of Vichy France and not occupied by Nazi Germany. At ''Cad ...

radio-intelligence and decryption center at Uzès, 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 Adam Rejewski (; 16 August 1905 – 13 February 1980) was a Polish mathematician and cryptologist who in late 1932 reconstructed the sight-unseen German military Enigma cipher machine, aided by limited documents obtained by French mili ...

and Henryk Zygalski 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 suspended the use of LCD at Cadix. In 1974, Rejewski explained that the LCD had two serious flaws. It lacked a

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 The commutator of two elements, a ...

("plugboard"), which was one of the strong points of the German military Enigma machine. The LCD's other weakness involved the

reflector Reflector may refer to: Science * Reflector, a device that causes reflection (for example, a mirror or a retroreflector) * Reflector (photography), used to control lighting contrast * Reflecting telescope * Reflector (antenna), the part of an ant ...

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.

Władysław Kozaczuk Władysław Kozaczuk (23 December 1923 – 26 September 2003) was a Polish Army colonel and a military and intelligence historian. Life Born in the village of Babiki near Sokółka, Kozaczuk joined the army in 1944, during World War II, at Bia� ...

, ''Enigma'' (1984), p. 135.

History

See also

References

Further reading