LACIDA, a rotor machine developed in Poland, uses conventional rotors, like a Hebern machine. However, it is unusual in that its moving rotors come in three different sizes; with 24, 31, and 35 contacts.
These rotors each move one step with every character enciphered, thus providing a period of 24*31*35, or characters.
The input alphabet consists of the alphabet with the letters Q and V omitted; the output alphabet uses all the letters, and all the digits except zero.
The conversion between 24 contacts and 31 contacts, and the conversion between 31 contacts and 35 contacts, are claimed, in the accounts I have read, to be accomplished by stators: rotors that don't move during encipherment, but which can be set initially to any position. (The rotors and stators are marked with the alphabet from A to Z, and at most 26 initial positions are used with any rotor.) In addition, an extra 35 contact rotor is used as a stator on exit. Originally, I thought that rather odd, as it seemed to require rotors made of rubber, but because mechanically, the rotors are similar to those of the Enigma, in that they contain one set of spring-loaded contacts, and a flange that serves as a gear, upon further reflection I realized that the conversion stators were possible, and would probably be achieved by placing the teeth on their gear flange at somewhat irregular positions.
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