A breakthrough took place in the thirties when a specialist Cipher Bureau was created in Polish Intelligence Agency. It was responsible for the security of Polish military codes with an ambitious goal of solving the Enigma riddle.

Three most talented students from the department of Mathematics at Poznań University were delegated in 1930 to reverse engineer this German technology - Henryk Zygalski, Jerzy Różycki and Marian Rejewski. The last one was even allowed to travel to Göttingen where he studied German, acquiring essential knowledge needed to decipher Enigma. After his return, the trio researched on alternate methods which could be helpful in reaching their goal. This was finally achieved in December 1932. Thus the machine considered to be a German engineering marvel was deciphered in less than three years!

The breakthrough in work on Enigma happened due to close collaboration of the Poles and French intelligence. A short-term acquisition of one of the Enigma's copies was crucial because it allowed the team to familiarize themselves with the mechanism and to create their own duplicate.

Enigma resembled a typewriter with a keyboard and rotating rollers with letters. Moreover, it was equipped with a crank which turned the rotors with numbers. The machine was also complicated by a plugboard changing the code every 24 hours and thus making it insanely difficult to overcome. When entering the text, ciphered letters appeared on a special surface with display windows. When receiving a message, the ciphered letters were typed in and as a result special bulbs lit up showing the decoded text.

Until the war broke out, Poles were giving the decoded messages to French and British intelligence. The allies were informed of decipherment in 1939 – when the Polish-German relations deteriorated rapidly.

During WWII the British were improving the Enigma's decoding technology. As a result, in many historical works, they are credited for the deciphering with the Polish contribution forgotten. Official recognition of the role of the Polish scientists in breaking the Enigma code had place after the Polish accession to NATO in 1999.

Do you know?

• Information sent with Enigma could be coded in 7905875085625 different ways.
• Between 1930 and 1932 the work on deciphering Enigma took place in Poznań. However, fearing the possibility of being tracked by German intelligence, it was moved to Warsaw and then to nearby Pyry (nowadays a part of Warsaw district).
• Jerzy Różycki died in 1942 near Balearic Islands during a mysterious plane crash over the Mediterranean Sea. Several workers of the Cipher Bureau returning from a business trip to Algiers lost their lives as well.
• Henryk Zygalski remained and settled in Great Britain where he taught Mathematics in a provincial school. He died in 1978.
• Marian Rejewski settled in Poland after 1945. During the first years after war, as a former worker of the Cipher Bureau, he was under surveillance from Urząd Bezpieczeństwa (Department of Security). The fact the he took part in decoding of Enigma was not discovered by the communists at that time. He only started mentioning his participation in his late memoirs, interviews and articles published in the seventies (back then the topic of Enigma was talked about again in Western Europe and for the first time references were made to the Polish contribution). After discovering the real merits of Rejewski, the Polish People's Republic authorities decided to reward the scientist. In August 1978 he was decorated with Order of Polonia Restituta by a Chairman of the State. He died two years later.
• Cryptology Day is celebrated on January 25 in order to honour the achievement of Polish mathematicians. The date was set in 2007 by the initiative of Mathematics and Computer Science Faculty at Adam Mickiewicz University in Poznań.