Question

Information is encoded in English alphabets (there are 26 distinct alphabets and capitalization is ignored) and four rotors are used in a rotor-machine based cipher. The random key is hardcoded on the rotor machine and corresponds to the substitution mappings within the rotors, where the substitution mappings are independent across the rotors. After the key is coded in the machine, the rotors rotate for every letter/encryption.

Question: How many letters would it take for the rotor machine to make a complete cycle, i.e., until it repeats itself?

Answer 1

The mechanism of the rotors have been explained in the question itself. The wiring is placed inside a rotor. When a signal is passed from one face to the opposite face of the rotor, and then rotated with a gear every time a letter was pressed, it is permuted into a different character. So while pressing A the first time might generate a Q, the next time it might generate a J. Every letter pressed on the keyboard would spin the rotor and get a new substitution. So it would be little difficult for the one who is trying to break the cipher to break it as it will take him much more time to do so.