Bletchley Park
Joan Clarke
Basic principles of Enigma, cable tapping, and NIS2
Extremely simplified, Enigma is a cipher device looking much as a typewriter with a keyboard with 26 letters. It has a rotor mechanism that scrambles a letter as resulting in another letter. The same device is used for encryption and decryption.
The encrypted letters are sent through the air using the Morse alphabet. Anyone with a radio receiver could read the messages, but only the one having an Enigma machine of the same type and setting as the sending Enigma machine can understand the message. More detailed information is available by the videos referenced below.
English codebreakers were able to break the Enigma code and recover the messages, which could be called the first cryptographic cyberattack happing for about 80 years ago. The principle for surveillants of Enigma communication is quite like today’s cable surveillants by national intelligence agencies. It almost certain that anywhere a cable can be monitored it is monitored.
NIS2 gives no protection against cable tapping (spying), and it would not have given protection against the Enigma tapping.
YouTube Enigma videos
There are produced several videos showing how Enigma works and how Alan Turing broke the Enigma and much more.
Below are links to two such videos, where the second one is a continuation of the first one. If you do not have a YouTube subscription, you have to accept some commercials and you have to stop the video when it gets to the end if you do not want to watch the follow-on video. As the videos starts under a new tab, just close the tab.
The following links are more centred around the history of Alan Turing and his achievements.