If you were to survey people: Who broke the Enigma code? You’re more likely to get the same response that it was none other than the legendary and brilliant mathematician Alan Turing of Britain. While that is definitely not wrong, it is also not entirely right. If it wasn’t for the grueling work and effort of the overlooked Polish mathematicians, cracking the seemingly formidable German code would be a lot harder. Thus, this was how the team of mathematics genii poured their brains out against the clock at that time when uncertainties and threats of German invasion over Europe were just an arm’s length away.

Securing Independence Through Interception

Poland as a country only gained its independence after World War I. As a young country, they had to work on everything to make sure that they would keep that independence. Its military leaders knew that to do that, they had to stay one if not two steps ahead of its potential adversaries. One way to do that was to intercept and decode those nations’ encrypted messages to make sure that they were not brewing any plan against their country. Lieutenant Jozef Serafin Stanslicki of the Polish Army was tasked to set up a new cipher section in May of 1919. This would later become the Polish Cipher Bureau of the country.

It turned out to be the right idea. They benefited from it when the Polish-Soviet War happened from 1919 to 1921. They successfully intercepted the Russians’ encrypted signal that did not change from what they used during World War I. Because of this, they won the conflict after the decisive Battle of Warsaw. To them, it was a clear sign that their successful interception was a major key to securing both success and independence had a future conflict arise.

The Enigma Code

It was in 1924 when the Poles intercepted baffling broadcasts of a new type of encrypted messages from the German Navy. These messages were almost impossible to decipher because, unknown to the Poles yet, the Germans started using the machine designed and created by German engineer Arthur Scherbius called the Enigma machine. Now, this machine was a whole new different level of encryption that would soon be used by all branches of the German military forces.

Enigma Machine A16672. (ArnoldReinholdCC BY-SA 4.0, via Wikimedia Commons)

This machine looked nothing more than an oversized typewriter, with the main purpose of encrypting messages by scrambling the words into what seemed like an indecipherable string of jumbled letters. The sender would type the message on the Enigma’s keyboard, and the three rotors inside the machine would change each letter of the message into a different one, which would light up on display above the keyboard. Each of these letters would be written down and then sent through morse code to the operator of a second machine, which was the receiver. The receiver would then enter these incomprehensible strings of letters into his machine. A reflector inside his Enigma would reverse the rotor process, lighting up the original letters that the sender entered into the first machine. Now, there was also a plugboard attached to the front of each Enigma to complicate the already complicated process further. Its purpose was to change each letter typed into the machine before the rotors altered them.

Exploded view of an Enigma machine rotor (Created by Wapcaplet in Blender.CC BY-SA 3.0, via Wikimedia Commons)

When the British, the French, and the Poles started picking up the messages sent through Enigma, they assigned linguists to work on deciphering them. They did not yield any result. Persistent in cracking these secret messages, the British kept on trying with their linguists. On the other hand, the Poles decided to try and consult with their mathematicians.

Numbers, Not Words

The Polish Radio-Intelligence office was soon merged with the cipher section in 1931 to form the Cipher Bureau. It was led by Major Gwido Langer and Captain Maksymilian Ciezki, who had long been convinced that the solution to unraveling the encryption was not through linguistics but mathematics. Before joining the bureau, Ciezki had first taught a secret course in cryptology at Poznan University, with three of his students showing highly promising potential— Marian Rejewski, Jerzy Różycki, and Henryk Zygalski. They all approached codebreaking mathematically and not linguistically. Ciezki hired these students to work for the bureau and help with the Enigma struggle.

Maksymilian Ciężki. (unknown-anonymous, Public domain, via Wikimedia Commons)

Meanwhile, in France, the Cipher Bureau counterpart was headed by Gustave Bertrand, a military intelligence officer. Their approach was different, as they decided the best course of action was not through linguistics or maths but by worming their way in through the German secrets with the help of Hans-Thilo Schmidt, whose brother was a high-ranking officer in the German army. He obtained the secret documents from his brother, one of which was the settings of Enigma for September and October 1932, as they changed these monthly. Upon getting the information, he passed these over to the British and the Poles.

The settings for the rotors were changed more often in 1936— from every quarter of a year to monthly and then to daily. The plugboards were also fitted with extra leads to increase the number of ways the letters could be changed.

By July 1939, the Cipher Bureau chiefs Gwido Langer, Maksymilian Ciężki and Rejewski and his team passed everything they knew about deciphering the Enigma to French cipher chief Gustave Bertrand and British Alastair Denniston. At that time, the Poles were able to crack at least 95% of the Enigma messages, all with the use of their mathematical approach.

Alan Turing got into the picture when the war broke out, and Poland fell. Alan Turing and his team were left to continue the works and build the Colossus machine at Bletchley Park, deciphering the more complicated German Lorenz cipher after Enigma.

COLOSSUS, part of the machine, presented by Director GCHQ to Director NSA in 1986 – National Cryptologic Museum. (Daderot, CC0, via Wikimedia Commons)

When the war ended, the works of Rejewski and the Cipher Bureau were all overlooked, if not totally forgotten as their country went into a communist break for about fifty years. All the while, Turing had completely cracked the Enigma that shortened the war by about two years.

The Polish government, after the hiatus, worked on having the names of Marian Rejewski, Jerzy Różycki, and Henryk Zygalski get the recognition that they rightfully deserve. A plaque of recognition was erected outside Bletchley Park to commemorate their contribution to the war effort.

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