Several very good articles on the Enigma machines (this one was a Model 3): https://www.cryptomuseum.com/crypto/enigma/ https://www.cryptomuseum.com/crypto/eni

Several very good articles on the Enigma machines (this one was a Model 3): https://www.cryptomuseum.com/crypto/enigma/ https://www.cryptomuseum.com/crypto/enigma/ "As early as mid 1928, the Poles had been able to purchase a commercial model of the Enigma and began studying its' components.... In January 1933, two other cryptologists collaborated with Rejewski's work and in the same month decrypted the first German messages." : https://polishgreatness.blogspot.com/2011/03/enigma-machine-part-i-polish-code.html https://polishgreatness.blogspot.com/2011/03/enigma-machine-...