During World War II, the Germans used ENIGMA, a cipher machine, to develop nearly unbreakable codes for sending messages. ENIGMA’s settings offered approx. 158,000,000,000,000,000,000 possible solutions, yet the Allies were eventually able to crack its code.
The machine was developed by the Dutch to communicate banking secrets. The Germans bought the patent in 1923 for intelligence purposes. Polish intelligence was able to purchase an ENIGMA at a trade fair and procure a codebook from a French agent.
In the 1930s, the French had recruited a source who had provided numerous classified documents about the machine; they then approached the British, the Czechs, and the Poles, who took the fullest advantage of the information.
Poland was the first to realize that the solution to breaking ENIGMA would most likely be discovered by a mathematician. Polish cryptanalysts as early as 1932 could decode German ciphers and, by 1939, they were able to successfully decipher messages written with an earlier version of ENIGMA using a replica machine that could emulate the way ENIGMA worked.
By 1933, Poland had demonstrated the ability to break those early ciphers and, by the following year, were producing their own ENIGMA machines.
July 24-26, 1939, Poland hosted a secret tripartite meeting with the United Kingdom and France to discuss the decryption of messages from the German ENIGMA machine. They explained how they had broken ENIGMA, produced two copies of the machine they had built, and shared technical drawings of their version of “the Bombe,” a device that could find ENIGMA keys by testing tens of thousands of possible combinations.
When Poland was overrun by Germany in September 1939, the Polish as well as French cryptanalysts shared everything they knew about ENIGMA with the UK, which allowed the cryptanalysts at Bletchley Park, including the famous Alan Turing, to finally crack the ENIGMA ciphers.