Sunday, May 16, 2021

How to use PicoEnigma, an Enigma Z30 Simulator

PicoEnigma is an Enigma Z30 simulator, a rare, numbers only Enigma Machine. 

Its mode of operation is similar to other Enigma machines, it has a keyboard and a lampfield, pushing a key sends electricity to the entry rotor (ETW), then the electricity goes from right to left through the rotor pack, comes back through the reflector (UKW), and returns from left to right through another set of wires in the rotor pack, goes into the ETW and out to a lamp. 

In this machine, the rotors can be rearranged, the ring setting can be changed and the rotor starting position can be set. To successfully decrypt a message, the machine settings must be the same used to enctypt it.

This simulator is designed to operate the same as the Enigma Z30 Simulator for the KIM Uno:

After the simulator is turned on, it is ready to encrypt a message. The rotor starting position is 4321. Pressing a key advances the rotors and lights the result. The result will be illuminated while the key is being pushed. Releasing the key turns the lamps off. 

During machine operation, all the lamps will be off if none of the black keys are pressed, or one lamp will illuminate when a black key is pressed. Pressing the red key enters the configuration mode. To indicate at a glance that the machine is in the configuration mode, all of the lamps are lit except for one. 

When only the first lamp is turned off, the rotor types are being changed. Pushing the keys above or below the displays changes the rotor type for that position. Each rotor can only be used once. Once a unique rotor combination is selected, pushing the red key again advances to the next setting. 

When the second lamp is turned off, the ring settings are being changed. The up and down keys are used to change this setting, Each rotor can be set differently to a number from 0 to 9. Pressing the red menu key advances to the next setting.

When the third lamp is turned off, the stepping mode is being changed. There were two kinds of machines, one with a traditional lever stepping and another with geared stepping. The lever stepping machines suffered from a double stepping anomaly where a 9 in any position steps that wheel and the one to its left.  A double stepping sequence is: 0088 0089 0090 0101 Geared stepping works like a car odometer and no digits are skipped. 

The stepping mode is indicated by the digit on the right. If it shows a 0, the machine is using lever stepping, if it shows a 1, it is using geared stepping. In this screen, pushing the leftmost up and down button also changes the brightness of the lampfield digits. 

Pushing the red menu button again turns all the lamps off and returns to the operating mode screen.

Pushing the up and down buttons changes the rotor starting position. The machine is now ready to encrypt numbers. 

To send a text message, an encoding scheme must be devised. Either substitute letters by two numbers A 01 B 02 ... Y25 Z26 or use a codebook where words are substituted by numbers, first translate the message to numbers then encrypt the numbers. 

To decrypt the message ensure the machine is set up exactly as the machine used to send the message. Ensure the starting position is set the same as well.

For example, to encrypt the message TEST, use the table below.

 A  B  C  D  E  F  G  H  I  J  K  L  M

01 02 03 04 05 06 07 08 09 10 11 12 13

 N  O  P  Q  R  S  T  U  V  W  X  Y  Z

14 15 16 17 18 19 20 21 22 23 24 25 26

The word TEST would be encoded as 20 05 19 20

Typing and holding one number at a time in the machine using the default settings after power up yields 44 57 43 94

The wheels should be at position 4329 after all the numbers have been typed. 

To decrypt it, use the up and down keys to reset the wheels to the starting position of 4321. Then type the encrypted message (44 57 ...) and the original message (20 05 ...) will be displayed.