The solution existed in their own country. In 1918 an engineer working in Berlin invented an enciphering machine in a high level of complexity. Through a process of changing the settings applicable altogether to transmission and reception throughout the connected network, messages will be inviolable.
The extreme subtlety of Enigma lies in the fact that the coding of a letter changes continuously by the action of the rotors according to an algorithm that applies to all machines. The basic plugboard wiring and the initial position of the rotors are renewed very frequently, even daily on the most secret networks, by instructions transmitted to the operators.
When hitting a key, the electrical signal is transmitted through the three rotors to another component named the reflector and passes back through the rotors to light a small bulb which reveals the reading value of the letter. The German military developed additional complications such as the interchangeable rotors or the movable reflector.
Widely used until the end of the war, the Enigma machines have mostly been destroyed at first by the Germans for not falling into enemy hands and then by the British after the end of the war. They have become very rare.
An Enigma of the first type with three rotors is estimated $ 160K for sale by Bonhams in New York on September 21, lot 73. The machine and the rotors are kept in matching numbers, which is very rare. The serial number indicates that this Enigma dates from the early 1930s, in the transition period between Reichswehr and Wehrmacht.
The code was not unbreakable despite the almost unlimited number of combinations. The discovery of a fast decryption process by Turing and his team is the most sensational feat of the cipher war and an extraordinary example of applied mathematics.
I invite you to watch the video shared by the auction house.