For the chronological categorisation of cryptography, I have proceeded as follows:
- Cryptography by hand (e.g. Caesar, Vigenére, etc., till around 1900/1920)
- Cryptography using machines (e.g. Enigma, TypeX, etc., till around 1960)
- Computational Cryptography (e.g. DES, AES, RSA, etc.)
- The Future of Cryptography (e.g. Quantum crypto)
The slots 1,3, and 4 are well documented and have a lot of different systems. But I'm struggling with slot 2: The heart of all the systems I found were rotors. Some were operated by mechanics, some by electro magnetism, but all use rotors for their cryptographic applications.
My questions: Does cryptography using machines only consist of rotor machines like Enigma, Purple, Typex, etc.? If other design principles exist, can someone give me an overview of them and maybe examples?