In all conflicts, cryptography has always played a crucial role in the secure transmission of information, ensuring that the enemy would not violate the secrecy of the transmitted information. Not only was World War II no exception in this regard, but it actually represented a significant step forward in the advancement of cryptographic technology and techniques.

The Enigma Machine

The Enigma machine was an electromechanical device invented by Nazi German engineers and used for encrypting and decrypting messages. During World War II, it was used primarily by military and government entities. Enigma looked like a typewriter, with a keyboard and a series of light bulbs. By typing the message in plain text on the keyboard, the operator automatically obtained the encrypted message, which could be sent securely via radio, telephone, or telegraph cable, depending on the available means. Using the same encryption key—that is, the same machine settings—the message could be decrypted by the recipient.

By changing the settings of the Enigma machine, the message's encryption key could be changed. To modify the Enigma machine's settings, there were three elements available:

• Rotors: The signal passed through rotating rotors, each with internal wiring that swapped the letters. Sequence The rotors' positions were crucial to encryption.
• Starting ring: The starting position of each rotor could be set.
• Switching panel: Before entering the rotors, the signal could pass through a switching panel, where the letter pairs were swapped.

Enigma settings were changed regularly, typically monthly. However, if the threat level was high, in periods of increased enemy activity, or in cases of suspected code compromise, the change frequency could increase. For example, German submarines, the so-called U-boats, were all equipped with Enigma machines on board, and if a U-boat was captured, German commanders could order an immediate change in the machine's settings, thus changing the code. the encryption key for the messages.

Despite various measures to maintain security, Enigma was not invulnerable. The Allies, especially Great Britain, developed cryptographic techniques to decipher some Enigma messages, gaining a significant advantage in World War II.

Turing at Bletchley Park

At Bletchley Park, during World War II, Great Britain assembled a very large task force, approximately 10,000 workers, with the aim of decrypting enemy codes, particularly the Enigma code. The task force consisted of highly qualified personnel, including mathematicians, linguists, and cryptographers. Among these, the figure of Alan Turing, the father of modern computing, certainly stands out. He was responsible for the mathematical analysis of enemy codes and the development of algorithms to decrypt them. Alan Turing's contribution was decisive in deciphering messages sent by Enigma, and the algorithms he developed were implemented in special electromechanical machines, such as the Bomba and Colossus, designed to automate the decryption process.

The work done at Bletchley Park had a significant impact on the course of the Second World War. The decryption of the Enigma code provided the Allies with crucial information on their opponents' battle plans and strategic moves, contributing to decisive victories that very likely shortened the duration of the conflict.