Thursday, December 31, 2099

Enigma Machine Simulator Documentation

Product documentation, build instructions and software for Enigma Uno, Enigma Z30, Pico Enigma and Mega Enigma, all of our Enigma Machine Simulators:

Sunday, June 28, 2020

Lessons learned from the last few projects

It is said that a picture is worth a 1000 words. This post condenses two years of learning into some instagram posts. 

Quoting another maker: "Just look, maintaining internal silence, until the meaning of my work becomes clear".

Here is a sample of my abilities before embarking on the projects on this page. This board was autorouted by Fritzing.

Enigma Uno

Keep part count low. Every added part adds complexity to a kit.

How to design laser cut enclosure with finger joints using Sketchup and Inkscape

Pay attention to how the grain runs on the wood. In Ponoko, it runs from left to right. All the vertical pieces tend to crack when a nail is driven into them.

External Lamp Field

How to use charlieplexing to illuminate a large number of LED <n> output lines control n*(n-1) LED

Route PCB using horizontal lines in the front and vertical lines in the back

Do not solder/work when tired:

Sinclair Scientific Calculator:

Pins A6 and A7 in the Arduino Nano are analog input only. They can be used to read buttons provided a pull-up or pull-down resistor is used.

Route tracks on seven segment display modules by laying down horizontal tracks under the displays and vertical lines in the back to connect the same pins on each LED module together.

Sometimes it is necessary to eliminate the current limiting resistor in order to obtain decent brightness out of LED modules (older style bubble LED displays).

When unsure how something will fit, order a small board and try different spacings. You do not need to provide holes for all the pins. Be considerate of Oshpark and size your board so they don't lose money on shipping:

How to design LED and Keyboard multiplexing circuits in order to drive and read the largest possible number of displays and buttons. What happens when multiple keys are pushed at the same time.

If this is the first time you are doing something, breadboard it

Don't forget the mounting holes, make sure the PCB has four holes in the corners. Holes are free.

Don't forget any extra holes for things like lid hinges. Again, holes are free.

A PCB does not have to be square. It can have gently rounded corners or other shapes. The inner sharp corners shown here are impossible as the board fab house will cut the outline of the board with a rotating bit, they will come out webbed. 

Tent those vias

The Arduino VIN pin takes anywhere from 3.9V to 12V. Operation from 4 AAA to a 9V battery is possible. A power switch can be used to select between two power sources. They do not need to be the same voltage, as long as only one is connected at a time.

Measure battery endurance to find out how long will a device run on batteries., either use a light sensitive CdS cell and an external arduino to record changes in resistance or save a value evey minute to EEPROM

Test displays before soldering. Assemble one device and keep the displays unsoldered or make a dedicated device with a Zero Insertion Force (ZIF) socket.

Put years / version numbers on the PCB. Text is free.

LED Dimming using PWM

Use solder with water soluble flux, makes cleaning things easier

7 Segment Digits can be vertically scrolled. The bit representation of the digits can be rearranged so a shift left or shift right will move the bits from the previous to the new segment.


14 Segment Displays can be vertically scrolled:

Use the F("") statement to store data tables in program ROM.

Pin D13 is connected to an external LED that can bias the pin. Avoid connecting this pin as an input. Either remove the LED or always set the pin as output and write high or low to force it to a known value.

Print a PCB design to paper and make sure components fit:

Don't trust Fritzing

Do not AliExpress when tired, you may buy a bag of unneeded components 

Sometimes soldering is the right solution, sometimes gluing is the right solution

Use the internal pull up resistor in order to connect the end of one or more push buttons to a pin, the other end to ground. Set the pin as input and write high to it. Reads 1 if nothing is pushed, 0 if pushed.

Use a fast pin library to read I/O. May need to write a wrapper function with a select statement to translate the pin number to the named variable used to access the pin.

Twist ties can be used to keep a top hinged lid in place, just make sure the PCB has a hole to secure it. Holes are free.
If your project has only LEDs and push buttons, there is no need for any extra external components. With careful coding they can be connected directly to an Arduino.

Use state machines as much as possible. Need to read many keys, that's one state machine. Need to drive many leds, that's another state machine. Need to do some time consuming processing and want to keep the keyboard and leds refreshed, split the time consuming task into simpler tasks using a state machine.

Route a PCB using the horizontal in front/vertical in back rule, then use vias placed under the components to minimize the amount of copper in the front layer.  

A daughter board can be used to hide the Arduino and the power connections on your project. It is cheaper to have 2 boards smaller than 100x100mm than one large board.

The new oshpark afterdark service can be used to embed some color on your boards. Try adding some logos or text to the copper layer.

Double check everything, why do we have a small logo on a side panel. Where are the hinge pockets

Double check your connections:

Try to put a standard Arduino power jack on your pcb

Try to put a battery compartment on your enclosures:

A 2 way switch can be used to select between an internal battery compartment and the power jack

Saturday, June 27, 2020

Pico Enigma and Mega Enigma Simulator Test Strings

Test strings to verify the correctness of PicoEnigma and MegaEnigma encryption:

To use the following string, press the menu button and change the machine to one of the models listed below, then paste the string into the Arduino Serial Port Monitor. The !AAA at the beginning changes the wheels to a know position before the lowercase characters are decoded. All of the test strings will result in AAAA when pasted to the correct machine. 

Machine Test String
I A !AAA sqcxf kbqcs rhjmm xtbuf zdmfc piinr dzwcs vutrv rbzus wgfcn cinio
I B !AAA ftzmg isxip jwgdn jjcoq tyrig dmxfi esrwz gtoiu iekkd cshtp yoepv 
I C !AAA twtvp tyixf fppyw svuso lidxh bbdok ztlzn fdube olqxf lhkhw vypem 
M3 B !AAA ftzmg isxip jwgdn jjcoq tyrig dmxfi esrwz gtoiu iekkd cshtp yoepv 
M3 C !AAA twtvp tyixf fppyw svuso lidxh bbdok ztlzn fdube olqxf lhkhw vypem 
M3 D !AAA jgtzx leioy lpwbe hfspo xlbrz zcbgo zfxvf hqjkj fkhmq ndvhr qzczi 
M3 D1 !AAA uipgp ofxtk mkeve tnbwq ohxgu keqoj bzvuc qqufm yfdgj udiuc kfzwq 
M3 D2 !AAA mnkhg vrjgm qrixe nolyc nxvow hdcfx ruqnb zqodc ixppd pdcwb oethu 
M3 D3 !AAA cfomw uxwfg cukke jyzom puzur rosde wsdmt kqqyo jznyi bdrxm ytbpr 
M4 B !AAAA ftzm gisx ipjw gdnj jcoq tyri gdmx fies rwzg toiu iekk dcsh tpyo 
M4 C !AAAA twtv ptyi xffp pyws vuso lidx hbbd okzt lznf dube olqx flhk hwvy 
N !AAA qwscm ijhvv vlrhx igxcw oddwu wzsjq wvfsk kxnqf gjqjn rupge ojrtv 
S !AAA zgdyt swlpz gmjdu zqqzd ewjzj drxpr whwmg jzvek uvnbe ptrkw hgfox 
D !AAAA hlkud thsyv icwnz wwdmw kgeog zyeqi hdtww lzeeu eifjx pgbke hiubr gcufi
K !AAAA inrkj yxuku tpiil mlqrg dofum bxrtz egtki tytpm zdzni usesg zyido 
R !AAAA tepwb pytxx msyid pumxb rqlwo nrzrf pikxr bdzcf oywyj uhumf unykn 
T !AAAA wlznv crjqp pgbdv nxgmg jgxcc iuwor lzcku oukit blizr ctoiu irfnt 
KD K !AAA wchug kzzsf nkioe liwwr ocksi etxxq pzfic euzff cwvsu fwmdg ertbn 
A865 !AAAA egwzq hddmg kuwqt xhuqv xrztx kehje gqtjo jkerw mpdec rttsv puejq 
G111 !AAAA qkuib bgtis ofzts jgmxi efgpi ubeuo bhujy ckssh jtxte wygmv nixec 
G260 !AAAA cknul qypie mmxyg htegz cdlvg tyxdb zgnvs kvqyh glvmz pyceu yczpn 
G312 !AAAA gjuiy cmdgu vttff qpzmx kvctz usobz ldzum hqmjx wtzwm qnnuw idyeq 

The test strings have been verified against Daniel Palloks Universal Enigma Machine Simulator and will also return all A if the wheel changing string !AAAA is removed and only the lowercase characteres are pasted.

To test the strings with either Pico or Mega Enigma using a computer.

1) Plug in either simulator into a computer.

2) Open The Arduino Serial Monitor

3) Press the red button, MACH will be displayed and illuminated in the lamp field

4) Use the up/down keys below the rotors or press K until KD K is displayed.

5) Press the red button repeatedly to exit the menu until all the lights in the lampfield turn off.

6) Copy the whole string on the KD K row: !AAA wchug kz...

7) Paste it into the Serial Monitor, all A will be displayed.

To test the strings with either Pico or Mega Enigma 

1) Press the red button, MACH will be displayed and illuminated in the lamp field

2) Use the up/down keys below the rotors or press K until KD K is displayed.

3) Press the red button repeatedly to exit the menu until all the lights in the lampfield turn off.

4) Start typing the whole string on the KD K row: "wchug kz..."

5) The letter A will be illuminated in the lamp field.

To test the strings with Palloks Universal Enigma:

1) Open this link:

2) On the drop down menu on the top right corner of the page, select KD (rewirable UKWD).

3) On the list above, copy the text on the KD K line starting from wchug kz...

4) Paste it on the input side of the Universal Enigma Machine Simulator. The output panel on the right should display all A.

Sunday, June 7, 2020

Assembly Notes for PicoEnigma

Pico Enigma Assembly Notes:

Top Board Assembly:

-Insert Buttons into PCB (1 red button under Enigma Logo, the rest, black)
-Solder one leg of Buttons while pushing down the PCB to keep them in alignment.
-Verify button alignment
-Solder the rest of the buttons.
-Test LEDs
-Insert LEDs into Lamp Field (short leg points towards buttons, long leg on display side)
-Double check short leg of each LED is in bottom hole.
-Solder one side of LEDs while pushing down on the PCB to keep them in alignment
-Verify LED alignment (double check LED polarity again before committing to soldering them all)
-Solder the other leg of the LEDs
-Verify the 14 Segment Displays
-Insert 14 Segment Displays on PCB (ensure the dot points down towards the lampfield)
-Solder one pin of each 14 Segment Display
-Verify 14 Segment Display alignment
-Solder the other pins
-Break 2 strips, 10 pins long from the double pin header.
-Fully insert the pin strips (short side up) from the bottom of the PCB,
-While pushing down on the PCB, solder 1 pin.
-Verify the pin strips are fully inserted and aligned properly.
-Solder the rest of the pins.
-Insert the power switch
-While pushing down on the PCB and watching the alignment, solder one pin.
-Verify alignment
-Solder the rest of the pins
-Trim the LED legs
-Trim the Power Switch legs very short, otherwise it interferes with the power connector.

CPU Board Assembly:
-Program the Arduino Mega
-Prepare a 10 pin length, a 4 pin length, a 2 pin length and 1 pin length of header pins.
-Insert the pin headers, long side towards flag side of CPU Board. Plastic headers should be on the non-flag side of the board.
-Insert the Arduino Mega on the short pins. The Arduino should be on the non-flag side of the board.
-Flip the board flag side up and while pushing down, solder 1 pin of each header.
-Flip the board, verify alignment and solder 1 pin of each header to the Arduino.
-Solder the rest of the pins.
-From the long female pin header, break 4 x 10 pin lenghts, clean the ragged edges.
-Insert the female pins on the Arduino side of the CPU Board
-Temporarily mate the Top Board to the CPU Board
-Solder one pin of each female header
-Verify the alignment and solder the rest of the pins.
-Separate the CPU Board
-Insert the Power Connector on the Arduino Side of the CPU Board
-Flip the board and tack solder one corner of each pin. Do not apply excess heat to this connector.
-Allow to cool and go back and finish soldering the pins. Do not apply excess heat to this connector.

PCB Bring Up (Initial Power Up)
-Mate the top board to the CPU Board
-Using a 9V battery and a male power plug, apply power to the board
-Flip the power switch to the EXT position.
-The board should power up and display AAAA (if not, check the solder joints, make sure the Arduino is powered up, connect to the board using the Arduino Serial Monitor at 9600 baud, upon powerup it will display PicoEnigma in the Serial Monitor)
-Repeatedly push the red menu button until V16 is shown. 
-Push one of the buttons adjacent to the 14 Segment Displays.
-The display should change to 8888 (if not, check the solder joints of the buttons)
-The lamp fields LEDs will turn on sequentially (if not, check the solder joints).
-Press each key, the corresponding lamp should turn off. (if not, check solder joints)
-Once all the keys have been pressed, the simulator will return to AAAA, use the buttons above and below each letter to change them. Verify the X and T letters display properly. In addition to 8888, this tests all segments. If one segment is not working, check the solder joints).
-Separate the CPU and Main Boards and clean the solder flux (if using water soluble flux, simply wash the boards under running water while scrubbing with a toothbrush)
-Dry the boards thoroughly, use a blower or canned cleaning duster to blow all the water from under the Arduino, the push buttons and the display.
Once the boards are thoroughly dry (do not rush this step), power them up and repeat the key/led test procedure above. If a key does not work or a single key turns off multiple lamps, dry those keys thoroughly.
-If the boards have mouse bites, this is the time to sand them off. Dry, clean and re-test the boards.

Battery Compartment Assembly:
-Locate the base piece of the case. Insert 4 screws in each corner of the battery compartment.
-Drive the screws in until they barely protrude from the other side.
-The first battery compartment piece has a hex nut opening, this allows retaining washers to be used on the battery door.
-Align the holes on the battery compartment piece on the protruding screws.
-While firmly pressing the battery compartment piece to the case base piece, drive the screws in, one at a time, ensure the battery piece is tight against the base piece. Drive the screws in until they begin to slightly protrude from the battery piece.
-The next battery compartment piece has a small round opening. Drive the screws in.
-The next piece will have a hex nut opening, install a nut in each opening. Drive the screws in.
-Install the rest of the pieces, Drive the screws in.
-Finally, install the flat piece with the single hole. The hole needs to be on the same side as the enigma logo and the power switch. Drive the screws in.
-Once the screws heads reach the case base piece, tighten them until the taper sinks into the base piece but do not over-tighten (hard woods such as walnut crack easily).
-Install a 9V battery on a power plug. Cut off and dispose of the male barrel plug (cut one wire at a time), The wires coming off the battery need to be as long as possible.
-Insert the leads from the battery into the battery compartment hole. Insert the battery into the compartment, wire first, the connector will be on the side opposite the hole. 
-Fold the battery leads flat against the top of the battery compartment.
-Fold them down the long side of the battery compartment.
-Install a tie wrap on outside of the battery compartment, holding the battery leads against it. This will prevent pulling on the solder joints if the battery is pulled.
-Put a piece of tape over the battery wires to prevent the keyboard buttons from cutting into them.
-Disconnect the battery
-Solder the battery wires to the CPU Board (separate from main board first).
-Install the battery
-Close the battery compartment.

-Install the 25mm brass standoff on the main board, use the plastic screws to attach them.
-Tie a simple knot on the twist wrap that serves to hold the lid in place. Insert from the bottom of the main board. Apply a drop of glue to the bottom of the board to secure the knot in place.
-Put a piece of tape over the keyboard pins to prevent them from cutting into the battery wire.
-Once the glue dries, connect the Main Board to the CPU Board (the CPU board needs to be connected to be battery compartment at this point). Ensure the Main Board pins are driven all the way into the CPU board headers.
-Using brass screws, secure the standoffs to the case base plate. 
-Turn the power switch to the INT position, the simulator should power up, if not, check the battery lead solder joints.

Case Assembly:
-Prepare the lid pieces, remove any remaining laser film.
-Install the screw that will hold the other end of the twist tie on the side piece. The screw should be above the hole in the PCB where the other side of the twist tie is installed. If using hardwoods, drive the screw in half a turn, then remove it and drill out the hole. Walnut cracks easily and if the screw is simply driven in, it will crack the side piece in half. Cut the tip of the screw off and install on the drilled hole.
-Mock assemble the lid piece, making sure the Enigma logo is to the inside and that the piece with the hinge pockets is near the Enigma Logo. The side piece with the screw should be on the left side of the lid, screw facing up.
-Moisten a paper towel and clean your fingers, cleanliness is paramount at this stage to prevent glue from finding its way into a flat surface.
-Lay down some paper towel and put all the lid pieces in their correct positions, The Enigma logo needs to be facing up so that is readable.
-Apply a drop of glue to the inside of each finger joint of a side piece. Insert into the Enigma piece.
-Repeat until all 4 sides are installed.
-Careful of not touching the glue, push all 4 sides tightly.
-Flip the lid face down into a clean piece of paper and push down on it.
-Set aside to dry.

-Repeat the process for the bottom pieces of the case, mock the side pieces and arrange them around the base piece. 
-Apply glue the side pieces and install them one at a time.
-Apply pressure to each side piece to ensure there are no gaps around them.

-Install the hinges on the lid. 
-Drive the nails in by grabbing them with multi-tool pliers and pushing them into the wood.. Once they are embedded in the wood, use the tip of the pliers to push them in all the way. 
-Align the lid with the bottom case and install one nail. Verify the lid aligns with the case.
-Install the rest of the nails.
-Minor lid misalignments can be corrected by gently twisting the lid when closed.
-Connect a power plug on the back of the simulator and observe the lid angle that keeps the lid from touching the power plug. 
-Fold the twist tie around the screw in the lid so the lid stays open at that angle. Twist the tie around itself and back around the screw so it does not work itself loose.
-Align and glue a Merkblatt

Sunday, May 31, 2020

Designing an UHR Switch for an Arduino based Enigma Machine Simulator

This article will explore some considerations when designing an UHR switch for a modern microcontroller based Enigma Machine Simulator.

The UHR Switch was an external attachment to the Enigma Machine. It is the small square device to the right of the Enigma Simulator shown below.

The UHR Switch connects to the plugboard and performs different substitutions depending on which of the 40 possible values is selected by using the rotary encoder on its face. 

The UHR Switch has 20 plugs, labelled 1a 1b 2a 2b 3a 3b .. 10a 10b.

A typical Enigma Code Sheet would list the 10 plugs to be installed as follows:

When using an UHR Switch, plug 1a would be connected to Q, 1b to P, 2a to W, 2b to Y, 3a to E, 3b to X, ending with 10a to O and 10b to L. Normally, a plug would substitute Q to P and P to Q, but the UHR switch may break that symmetry depending on the setting used. For compatibility with machines not using it, position 0 performs the same symmetric substitution as the plugs Q to P and P to Q. Positions that were multiples of 4 (4,8,12...) perform different symmetric substitutions, for example, position 4, as wired above would substitute Q to B and B to Q.

The image below, found under the Wiring section of the CryptoMusum UHR article, describes the input and scrambler disk wiring.

The link below lists all substitutions produced by the UHR. It can be used to verify the correctness of an implementation

1a->8b  7b->9a
2a->9b  1b->6a
3a->3b  8b->4a
4a->2b  6b->10a
5a->1b  2b->7a
6a->10b 9b->3a
7a->7b  5b->1a
8a->6b  3b->8a
9a->5b  10b->2a
10a->4b 4b->5a

The enigma machine uses the plugboard twice for each letter encoded. When a key is pressed, it first goes through the plugboard to be either substituted by another letter or be left alone. Then it goes into the rotor pack, through the reflector and back trough the rotor pack to be encoded into a different letter. Lastly, it goes through the plugboard again before going to the lampfield. 

A microcontroller implementation of an Enigma Machine with a plugboard would perform all of the steps above. Typically, all 26 plugs would connect directly to a microcontroller with sufficient I/O pins or to an IO port expander. Either way, each pin needs to be bi-directional and can be used as an output or an input. When used as an input, an internal 10k pull up resistor can be activated so the port will read 1 if not connected to anything. 

To see if a plug is installed, first all the ports are switched to input and the internal pull up activated, then the port corresponding to the letter to be substituted is switched to output and driven low. One by one all the other ports are read, if a plug is not installed, it will read as 1. If a plug is installed, another port will read 0. If all the other ports are read and neither returns 0, a plug is not installed and that letter is not substituted. 

This behavior is performed twice, once when a key is pressed to see if it needs to be changed on the way to the rotor pack and once more as it comes out of the rotor pack to determine the letter to illuminate in the lamp field. 

Let's use Daniel Palloks Universal Enigma to analyze how the UHR works. A default M4 machine with B reflector and Beta thin wheel has been selected. The following plugs have been installed QP WY EX RC TV ZB UN IM JK OL. The plugboard has been activated and UHR has been set to position 06

The first two lines in the signal monitor show the substitutions performed by the UHR.

         abcdefghijklmnopqrstuvwxyz    top
         aotdxfghbvewrjczmyspnqkiul    bottom

these can be expanded using the actual plug substitutions listed above (1a->8b) as shown below:

         11 22 33 44 55 66 77 88 99 00
         ab ab ab ab ab ab ab ab ab ab
Plugged: QP WY EX RC TV ZB UN IM JK OL top 
Uhr: 06  MZ KU XI YT PQ LO NJ BR VE CW bottom
         86 97 38 25 11 00 79 64 53 42
         ba ba ba ba ba ba ba ba ba ba
Lets press A:

The arrows indicate the direction the signals are traveling. The topmost green arrow going down into A shows the keyboard going into the UHR, since this letter is not plugged, it goes into the ETW, the entry rotor as itself. It comes out of the rotor pack as F, and again, this letter is not wired to the UHR, so it goes out to the lamp field as itself.

Now lets press A again.

It goes in as A, an unplugged letter, so it goes into the rotors as A, comes back out as T, a plugged letter and the UHR performs a bottom to top lookup and goes out to the lampfield as C.

Now lets press a plugged key, P:

It goes in as P, a plugged letter and the UHR performs a top to bottom lookup, sending it into the rotor pack as Z. It goes through the rotors and comes out as A, an unplugged letter, so it continues as an A to the lampfield..

Lastly, lets press P again:

It goes in as P, a plugged letter and the UHR performs a top to bottom lookup, sending it into the rotor pack as Z. It goes through the rotor pack and comes out as O, a plugged letter and the UHR performs a bottom to top lookup and goes out to the lampfield as B.

Now, lets press P until the green arrow going from the keyboard into the UHR and the red arrow coming from the rotors out into the UHR align:

P gets translated by the UHR as Z when going from the keyboard into the rotors and the resulting P gets translated by the UHR as T when going out from the rotors into the plugboard.

And this is the point where one realizes that a software implementation of the UHR switch on a simulator that has a plugboard with a single plug per letter is not a straightforward task. The UHR needs to know whether the signal is going into the rotors or coming out of the rotors.

The real enigma machine uses two connectors per plug, A normal wired plug crosses the top connector on one side to the bottom connector on the other side and vice versa. The plug has an internal shorting bar that connects to top connector and the bottom connector. The plug pushes that shorting bar with an insulated tip and connects the top and bottom of one letter to the bottom and top of another letter. The UHR connects the top side of the plugs to the bottom side of the plugs using the A and B connectors. 

A software UHR with single connector per letter needs to somehow differentiate whether the signal is going into the rotors and it needs to perform a top to bottom translation or it is coming out of the rotors and into the UHR and it needs to perform a bottom to top translation. 

The different substitutions have been highlighted below. The entry substitution is the highlighted P on the top left side of the diagram, that gets translated through a top to bottom lookup into a Z. The exit substitution is the highlighted P on the bottom right part of the diagram, that gets translated through a bottom to top lookup into a T.

         11 22 33 44 55 66 77 88 99 00
         ab ab ab ab ab ab ab ab ab ab
Plugged: QP WY EX RC TV ZB UN IM JK OL top 
Uhr: 06  MZ KU XI YT PQ LO NJ BR VE CW bottom
         86 97 38 25 11 00 79 64 53 42
         ba ba ba ba ba ba ba ba ba ba

Another thing to keep in mind is that the UHR does not see all the letters being encoded. 

A->F (A is unplugged, F is unplugged, the UHR sees neither)
A->C (A is unplugged, C is plugged, the UHR sees only the exit path)
P->A  (P is plugged, A is unplugged, the UHR only sees the entry path)
P->B  (P is plugged, B is plugged, the UHR sees two signals, one as an entry, one as an exit)

Furthermore, in the P->Z translation and P->T translation, the UHR sees both as P, but in one case the correct translation is Z and in the other one is T.

So, the UHR is not in a position to monitor all the letters being encoded and a letter sometimes needs to be translated as an entry signal (top to bottom) and sometimes as an exit signal (bottom to top).

An initial solution was to have a state variable in the UHR device. The first signal would be translated as top to bottom. Then when the first signal is released, activating a second signal would get translated as a bottom to top. The enigma machine would then perform two plugboard queries when a key is pressed. The first query would return the top to bottom substitution and the result would get used to send it through the rotors. The second query would be performed just to keep the UHR in sync with the enigma, its result would not get used. The letter would then get sent through the rotors and it would come out as a different letter. The output letter would be queried through the plugboard again. The first query would be translated by the UHR as a top to bottom translation and it would get disregarded by the enigma logic. The enigma logic would then query the plugboard again and the UHR would perform a bottom to top translation. The enigma logic would use that result to illuminate the lampfield. This logic works but it tends to get lost if the UHR is changed while a key in the enigma is pressed.

Since the UHR is in no position to see all the encoded letters, it needs to return the top to bottom and bottom to top translations for a given letter. A better solution is described below.

When the Enigma activates a letter in the plugboard, the UHR first activates in response the result from the top to bottom lookup. This is noticed by the pluigboard reading logic in the enigma simulator. After a period of time, the UHR releases the first response, and activates the result corresponding to the bottom to top lookup. It is up to the enigma and plugboard logic to decide whether the first or the second result gets used. 

The UHR code below performs the top to bottom lookup and activates that plug

The plugboard logic detects the first and second responses and returns the one value the enigma needs

The enigma logic requests the first value going into the rotors

And the second value when going out of the rotors and into the lampfield
And now it makes sense why the UhrBox-E kit included a replacement CPU for the Enigma-E. If an enigma simulator is developed first, all the subtleties of developing an external UHR switch are not going to be known before hand. A protocol and timing between the Enigma and the UHR needs to be developed. 

Wednesday, May 20, 2020

The listing for NanoEnigma is live


This is #NanoEnigma by @arduinoenigma, a simulation of the numbers-only Enigma Z30, a rare leaf in the Enigma Machine family tree. Similarly to their bigger cousins, this machine uses rotors and an ever changing maze of wires to encrypt numbers entered through keys labelled 0..9 into similarly labelled lamps.

The existence of the Enigma Z was first revealed by (Arturo Quirantes (2004) MODEL Z: A NUMBERS-ONLY ENIGMA VERSION, Cryptologia, 28:2, 153-156, DOI:10.1080/0161-110491892845).

More recently, three machines were discovered in Sweden and their wiring, including their rotors, reflector and entry rotor were recovered. (Anders Wik (2015): Enigma Z30 retrieved, Cryptologia, DOI:10.1080/01611194.2015.1055387)

Operation is similar to other enigma machines. The rotor order and starting position are the encryption key. Pressing a key first advances the rotors and then sends electricity through the rotors until the reflector is reached and then the current travels back through a separate set of wires in the rotor maze until it comes out and illuminates a lamp. Same as a real machine, the key must be held down for the lamp representing the encrypted result to be illuminated. Releasing the key turns off the lamp.

Pressing and holding the same key again moves the rotors and another lamp is illuminated. Decryption is achieved by setting the machine to the same starting position and typing the encrypted numbers, the decrypted numbers will be illuminated in the lamp field.

This simulator is an attempt at a reconstruction of a working machine, applying the rotor and reflector wiring recovered in the Wiks article to the way an Enigma Machine is known to operate. The rotors, by default step using a simulated lever mechanism that suffers of the double stepping anomaly. A geared stepping mechanism that works similarly to a car odometer is also implemented. 

Since no surviving machine has been powered up, this simulation cannot be verified against an actual machine. The assumptions made in its development can be observed by searching for the project log titled "Using the Excel Paper Model to encrypt a message". This log shows how to use a paper model named "6502 ENIGMA Z ROTOR DEFINITIONS v3.xlsx". 

This simulator is also compatible with another one written for the KIM Uno.

This simulator is powered by an Arduino Nano and its software can be modified. Its USB port is exposed. The source code for the firmware is available in Gitlab ("EnigmaZ30Simulator" Project ID: 12769524).

Power is supplied by one of three possible sources: 4 internal AAA batteries, an external 6-9V power source using a standard Arduino male barrel jack, or its USB connector.

The case is made from laser-cut 3mm Birch plywood.

The front panel of this product is the actual Printed Circuit Board (PCB) to which all the components are mounted. As such, be careful with electrostatic discharges to any of the exposed contacts. I have not fried one yet and if careful, neither will you.

This is not a toy, but a delicate product, the hinges and nails are small, if treated with care, it will provide years of service. I still have simulators made in 2015 that work just fine.

This is a not a factory made product, it is hand-made and has its unique imperfections. You are getting the actual product shown in the pictures. Ships immediately anywhere in the world.

Lastly: A lot of care went into making this. Enjoy... 

Monday, May 18, 2020

A Picture of Four Different Enigma Machine Simulators

From left to right:
-Original Enigma Uno: Enigma I, M3, M4, UHR Switch, Printer
-Nano Enigma: an Enigma Z30, a numbers only Enigma Machine.
-Mega Enigma: A full featured universal Enigma Machine Simulator.
-Pico Enigma: Same as Mega Enigma, minus the plugboard.

Sunday, May 3, 2020

The Listing for PicoEnigma is live.

Pico Enigma PE0001:

eBay Listing for PicoEnigma

This is #PicoEnigma by @arduinoenigma. It is an Arduino based Universal Enigma Machine Simulator that's open source and hackable. It simulates all well known enigma machines that have 26 keys. There are a couple of oddball machines like the Swedish Enigma B A-133 and the Enigma Z30 that this does not simulate. For machines with a plugboard, one is emulated in software as well. Once 10 plugs are set, an additional scrambler, a software emulation of the UHR switch can be enabled and set to any of its 40 positions.

The accuracy of this simulator has been verified against Daniel Palloks Universal Enigma v2.5.

The list of machines emulated is as follows:

Enigma I (A, B, and C reflectors), Enigma M3 (B, C, and rewirable UKWD reflector). Enigma M4 (thin B and thin C reflectors), Norway "NorEnigma", S "Sonder-Enigma", D (commercial), K (Swiss), R "Rocket" (Railway), T "Tirpitz" (Japan), KD with rewirable UKWD, A-865 Zählwerk (1928), G-111 (Hungary/Munich), G-260 (Abwehr, Argentina), G-312 (Abwehr, Bletchley)

The menu structure is as follows, upon powerup, the simulator shows the rotor position (AAAA) and is ready to encode with the current settings loaded from non-volatile internal storage memory (FLASH). Pressing an A-Z key animates the rotors rotating.

Depending on the rotor position and the machine type, anywhere from 1 to 4 rotors will turn. For lever stepping machines, the double stepping anomaly is faithfully replicated and can be observed by setting the rotors to AADQ. Geared stepping machines and their more frequent irregular stepping are also simulated.

Once a key is pressed and held down, the encoded result is shown in the lamp-field. Because of the reflector, which sends back electricity through another set of rotor contacts, a letter can never encode to itself. This property was exploited by Bletchley Park to break the Enigma Cipher.

The following 3 behaviors were implemented in this simulator for that extra physical realism. They were verified with an actual Enigma Machine.

1) While a key is held down, the rotors can be manually moved forward by pressing the button under each rotor, and a new lamp corresponding to the result for the new rotor position and pressed key will illuminate in the lampfield, this may or may-not help in cryptanalysis of Enigma. If the stepping lever is not engaged, the left rotors can be moved backwards by pressing the button above the rotors. Since the stepping lever is always engaged in the rightmost rotor when a key is pressed down, the rotor can only be advanced, never moved back. Once the middle rotors are in position after the double stepping anomaly has just occurred, they cannot be moved backwards either, only forward.

2) While a key is held down, a key from another row can be pressed as well and the result for the additional key will illuminate in the lamp fields. Due to limitations of the keyboard circuit, only one key per row can be pressed without distorting the position shown in the rotors. If a key encodes to a lamp in a different row and that key is pressed, both lamps are turned off, as the normally closed contacts in the keyboard are opened up, releasing either key illuminates one light in the lampfield. For example, if pressing Y, illuminates G, while holding down Y, G is pressed, the G lamp turns off. If G is released, G illuminates.

3) Up to three keys (one in each row) can be pressed at the same time, one of the rotor change buttons can be pressed as well, the rotors will change and up to three lamps will illuminate.

Pressing the red button enters the configuration menu. Holding the red button for approximately two seconds performs an emergency zeroise of the machine configuration. It returns to an M4 with B reflector, Rotors B 3 2 1, Ring settings A A A A and all plugs are removed. Those settings are then saved to internal non-volatile memory.

The machine can be identified as a glance as being in the configuration menu since multiple lamps in the lampfield will be illuminated without any keys being pressed. The illuminated letters will match the menu name, for the MACH menu, the M, A, C and H keys in the lampfield will be lit.

The menu structure is as follows, the machine starts at AAAA in the encryption mode, pushing the red menu button once changes to MACH, the first level menus. Pushing the menu button changes between (AAAA, MACH, UKWD, ROTOR, RING, PLUG, UHR, V16). Once in a first level menu, pushing either of the rotor change buttons enters the second level menu and examines the current setting for that menu, pushing the red menu button again advances to the next first level menu without change. Pushing the rotor change buttons again while inside a menu, changes that setting. All of the settings can be changed in order, or one at a time. Keyboard accelerators can be used in some of the submenus.

For example, while inside the MACH menu, pushing N, instantly changes to the Norenigma machine. The ukwd, ring and plug settings can be set with the up/down buttons or by typing them. Some of the menus, like UKWD and PLUG can be hidden if the currently selected machine did not have those features.

The last menu entry shows the software version running on the simulator (V16). If any of the rotor change buttons is pressed, the lamps are illuminated one at a time. Their brightness can be adjusted by pressing the rotor up/down keys. Once all the lamps are illuminated, pressing a key turns off the corresponding lamp. Once all the lamps are extinguished, the simulator returns to AAAA, the encoding mode.

Pushing the menu button repeatedly exits to AAAA, the encoding mode. The menu button is then disregarded for one second to prevent reentering the MACH menu accidentally.

While going from V16 to AAAA to exit the menu, if any of the settings have been changed, the display blanks for a second while the machine configuration is saved to internal non-volatile memory (FLASH). The settings are saved in duplicate so in the unlikely event that the power cuts off during the write operation, the last known good settings can be recovered from the unaffected memory block.

This can also be operated through the included USB cable. Connect it to a computer and open the Arduino Serial Monitor at 9600 baud. Any characters sent will be encoded and displayed in groups of 4 or 5 characters depending on the machine selected. The position of the rotors can be altered through the serial port by first sending an exclamation mark ! followed by the rotor position (!aaaa) any extra characters after the 3 or 4 rotor position will be encoded. (!aaaaencodethis). The machine type and configuration cannot be changed via Serial Port. The machine needs to be the encoding mode for the Serial Port encoding to work. Any characters sent while inside the menu will be disregarded. 

This device can be powered from an external battery (4-9V) through a standard Arduino center positive barrel jack, an internal 9V battery or through the exposed USB connector. The power switch is used to select between the internal and the external power sources. To turn the unit off, select a power source that is not connected. The USB connector is unswitched and can be used to power up the unit indefinitely. A 9V battery lasts approximately 6 hours in standby mode.

The case is made from laser-cut 3mm Birch plywood.

This device is hackable, want to turn it into a Akafugu word clock? Go ahead, it uses an Arduino Mega compatible Meduino Mega2560 R3 Pro Mini ATMEGA16U2 with 253KB available program space, 8KB RAM and 8KB FLASH. The source code for this simulator is provided at GitLab.

What do you get:
1x PicoEnigma S/N PE0001
2x 9V Barrel Jack Power Plug
2x 9V Batteries
1x USB Cable

Dimensions: 105mm x 95mm x 43mm
Weight (empty / with internal 9v battery): 188g / 234g

Menu Structure:

    (lampfield and keyboard selftest/lampfield brightness adjustment)

The front panel of this product is the actual Printed Circuit Board (PCB) to which all the components are mounted. As such, be careful with electrostatic discharges to any of the exposed contacts. I have not fried one yet and if careful, neither will you.

This is not a toy, but a delicate product, the hinges and nails are small, if treated with care, it will provide years of service. I still have simulators made in 2015 that work just fine.

This is a not a factory made product, it is hand-made and has its unique imperfections. You are getting the actual product shown in the pictures. Ships immediately anywhere in the world.

Lastly: A lot of care went into making this. Enjoy...

Sunday, April 5, 2020

Setting Up MegaEnigma to decode the Rasch Message, a 1942 intercept by H.M.S Hurricane

This is part of the documentation of MegaEnigma, a Universal Enigma Machine Simulator:

In the following videos, the machine will be set up to decode a real U-Boar message, available here:

MegaEnigma 1/8: All Menus and Brightness adjustment

MegaEnigma 2/8: Selecting an Enigma Machine model.

MegaEnigma 3/8: Selecting the Rotors

MegaEnigma 4/8: Ring Settings

MegaEnigma 5/8: Viewing the installed plugs.

MegaEnigma 6/8: Confirming All The Settings

MegaEnigma 7/8: Setting up the starting rotor position.

MegaEnigma 8/8: Decoding the message (BOOT KLAR)

Additional Menus:

MegaEnigma: UKWD, Software Plugs and UHR Switch

MegaEnigma: UKWD menu appears for machines that feature it.

MegaEnigma: UKWD menu: Viewing plugs in UD and BP notation

MegaEnigma: UKWD menu: editing plugs

Tuesday, March 17, 2020

Enigma UHR Switch Test Vectors

While working on an Arduino based Uhr Switch to be externally attached to an Enigma Machine Simulator, the need to verify the correctness of the implementation arose.

The UHR switch is described here:

A reference implementation can be found here:

Most likely nobody needs these, but here they are just in case:

Enigma UHR Switch Test Vectors...