Well, one day or one evening, I don't remember which, one of the younger mathematics students came up to me and said that on such-and-such a day, at such-and-such an hour, Professor Zdzislaw Krygowski, director of Poznan University's Mathematics Institute, wanted me to come to the Institute. This student had some sort of list, and he would go and tell each of the persons on the list about this. Not everyone was invited, only a certain number of selected students. What the criteria were, I can only guess . ... I expect it wasn't Professor Krygowski who selected the students but rather Section II, the Intelligence Section of the Polish General Staff, that had made the selection. Probably there had been correspondence between Section II and Professor Krygowski, and on the basis of this correspondence Professor Krygowski had given them a list of all the third- and fourth-year students ... who were close to graduating, and then Section II had by its own methods conducted some kind of selection. In any case, not all the students were selected ...

A few weeks into the course, the students were given real German ciphergrams to solve. The students were told that this system had already been broken although for a time some consultants of the Polish Cipher Bureau had considered it unbreakable. The students were also told what the text was about which helped to narrow down the vocabulary used. A couple of hours later, some of the students including Rejewski, Zygalski and Rozycki proved capable of decoding the message. As the course progressed, the ciphers became increasingly more difficult. Unsuccessful students started dropping out of the course and others decided they did not have enough skill to keep going. Only the above-named three students managed to reconcile their regular course work with the cryptography course.

There were a few secretaries, a few employees ... . In addition, when passing through the corridors of the Staff Building we knew some people by sight, like the manager of the Russian ciphers cell and the manager of the Polish ciphers cell. Soon, Rozycki, Zygalski and me were so thoroughly isolated from the rest of the staff that even the janitor who brought tea for breakfast did not have the right to enter our room, at the door of which, on top of that, a black curtain was hung, as a result of which our room was jokingly nicknamed "Black peace".

The Polish team tackled what was considered by the German military to be unbreakable. These twenty-year-old mathematicians, unversed in traditional schematic routines of academia, using their linguistic and imaginative abilities, formulated bold new theories of probability, permutations and group theory.

At the end of 1932, Rozycki was entrusted with an additional task related to the theoretical foundations of breaking Enigma codes. Using a converted commercial machine and a photocopy of the day keys provided by Captain Gustav Bertrand from the French intelligence service, Rozycki and his colleagues managed for the first time to read German military radio messages from the period from September to October 1932, secured with the Enigma. However, this was only a partial success, as it was due in part to the mistakes of the German ciphers, who used repeated letters in the ciphers and thus used only a small part of the machine's capabilities.

Completely unraveling the mystery required extremely hard work. Initially, the number of combinations generated by the Enigma machine was set to $3 \times 10^{114}$. Determining the design details allowed the number to be reduced to 105,456 combinations. This, however, was still very large, and developing a method for finding the correct key among all possible machine settings was difficult. ... Rozycki's contribution to the development of Enigma was significant. He was responsible for the invention of the so-called 'clock methods' which made it possible to determine which Enigma rotor is in the first position. It was based on a brilliant observation about the statistical properties of the language and the picking of identical pairs of characters vertically from the German text. If their number in relation to the length of the message corresponded to German, the shift was appropriate. In this way, Rozycki independently developed a method that was the first theoretically described by the American cryptologist William Frederic Friedman in the 1920s under the name "Index of coincidence".

... on that day [9 September] we were so close to personal tragedy when we hid from a raid: myself with our child, Jurek [Rozycki] and Zyga [Zygalski] when a bomb fell nearby. A deep funnel had formed in front of us, but luckily we are only partially covered with sand.

... three young Poles - Jerzy Rozycki, Marian Rejewski and Henryk Zygalski. ... the experience of these people can shorten our work by months.

... there was a deeply disguised French counterintelligence in the area, organised by Vichy state officers sabotaging the activities of Marshal Philippe Petain and cooperating with the Allies. Jerzy Rozycki then used the false name Julien Rouget. The conditions in which he worked were not the best. The cryptologists were placed in rather primitive quarters without running water, but the Polish mathematician received a salary and food from the French.

A group of several dozen people from Wyszkow participated in the commemoration of Polish cryptologists - Marian Rejewski, Jerzy Rozycki and Henryk Zygalski - which took place on 6 September [2019] in Krakow. In the Crypt of the National Pantheon, in the crypt of the Church of Saints Peter and Paul, urns with soil from places related to the death or burial of the Polish cryptologists were placed in a sarcophagus. For Jerzy Rozycki ... it is a symbolic grave.

The primary task for the Board of the National Pantheon Foundation was to create a symbolic grave for Jerzy Rozycki, for whom, despite the benefits he gave to his country and the world, there was no place that could be described as his eternal resting place. However, taking into account the fact that the achievements in deciphering the Enigma was the work of all three mathematicians equally, the Pantheon Chapter decided to erect one sarcophagus in the Crypt, containing the earth from the three places related to their deaths, i.e. the bottom of the Mediterranean Sea, from Chichester and from the vicinity of the grave in Powazki.

In 2002, a group of history and cryptology enthusiasts proposed commemorating this achievement with a monument where the history of breaking the Enigma ciphers began - in Poznan, Poland. ... From the 24 proposals received, the jury unanimously selected the design by Grazyna Bielska-Kozakiewicz and Mariusz Krzysztof Kozakiewicz. Their work represented the prism of a regular triangular base - its sides covered with rows of numbers. On each side of the monument, the name of one of the codebreakers emerges from the chaos of numbers. In its verdict, the jury remarked that the winning project "represents in the purest form the brilliant thought of the three mathematicians. The artist himself seems to step aside permitting the spectator to contemplate the purely intellectual achievement of the three cryptologists."

... modelled on an educational and scientific institution, the new Enigma Cipher Centre is divided into three parts which include opportunities for visitors to test their own code-breaking skills, send messages in morse code and see an actual German Enigma machine on loan from the Museum of Polish Arms in Kolobrzeg.