Army Enigma Comic Strips, Rod and Alphabet Squares

Enigma Wheels:
Rings
Wheel Starts

Steckers
Enigma Rod Squares

Cipher Text Crib
Rod pairs at start

Enigma Rods

Wheels in square L for left wheel only LM for Left and Middle, LMR for all.

Enigma Alphabet Square


German Army Enigma is demonstrated.

The Rod Square was an important tool in breaking Enigma. It shows for one wheel the encipherment of the alphabet down the right hand side for each of the wheel start positions along the top of the square. Click on "Rod Squares" for Enigma to show the squares for the left hand wheel number in the "Wheels" text box.

Rod pairs were an important way of breaking the unsteckered Enigma. The "Rod Pairs" part of the procedure demonstrates the breaking of the right hand wheel and its setting.

Rod Pairs allow comparison between the rods and a cipher text and its guessed Crib. If the right pair have been selected, the rods reveal some same letter pairs, at the same positions, as in the cipher/crib. When this happens more than once it was known as a "Click" and the seperation between Clicks, known as the "Click Distance".

The rods have to be brought into a poition corresponding to the original Enigma encipherment of the cipher text and this is achieved by the Startletter. This in effect rotates the rod letters by the numeric value of the start letter.

The default text settings show the correct position, H, of the start and the correct rod pairs. The multiple Clicks confirm this start and wheel number.

If you want to try for yourself, clear the Rod Pairs box and put A in the start box. Now click on Rod Squares and look down the first column to find J and D, the first letters of the cipher/crib pair. They are in rods k and r so enter KR in the rod pairs text box and click on Enigma Rods. The rods pair lines up with the start of the cipher/crib pair and show a single match on the first pair, as it should since that is what you have chosen. But it shows no other matches so it is probably not the correct start. So now move to the B column and find J and D again. This time they are on rods f and g so clear the pairs box and just enter FG and start B. On clicking Enigma Rods again, the lower case index above the cipher text moves on one letter but still no clicks on the rod pair. So now try "ot" rods for JD in column C. This gives a click at distance 1, not good but needs investigating so look up the rods which contain the cipher/crib pair after the click, ie NE in column D. This gives rods "xd" and add XD to the rod pairs list. Clicking Enigma Rod Pairs shows both rod pairs but no clicks on the second rods. Now go back to column D and pick up JD rods "pq" putting the start on to D Progress like this with no results until you get to column H, ie start H. Now JD is on rods "yz" and bingo! A long distance click. The next column, I gives rods "ks" for AE add this to the pairs list. No extra clicks but now try rod cl for NE gives a click and then ZW on rods "aj" gives three clicks which means that H is almost certainly the correct Enigma wheel start.

This might seem a long process but it was remarkably quick with practice and remember you are getting towards defeating a 105,000 combination search space! The Alphabet Square is shown for Army Enigma. It was important in finding wheel start positions when cribs were available for messages set in depth.

Click on "Alphabet Square" to show it.

The wheels selected refer to the rightmost wheel selected and assume that any wheels to the left of this wheel do not increment, ie there is no carry.

If just L is selected for the leftmost wheel, then it is as if the middle and right hand wheels were not present. This therefore gives just the encipherement by the left hand wheel and the Umkerwalze for all possible start positions of the left hand wheel.

If LMR is selected then all wheels are included but again, only the right hand wheel increments as per the letters along the top of the square. The start positions of the middle and right hand wheels can be changed by altering the wheel starts text box. Thus alphabet squares can be produced for various combinations of wheels and starts except for the wheel being incremented. The contents of the wheel starts box are ignored for the wheel being incremented and any wheel to its right.

The rod or alphabet squares or the instruction text can be printed but make sure that the square has focus by clicking on it just before printing.

The comic strips are also produced below the rod squares. These strips are for the same wheel, rings and start positions as the alphabet square.

Any entry in the steckers box and the rings box, is ignored in producing the rod Square but will be included in the comic strips.

The comic strips presentation is the same as in the comic strip decoding procedure.
A background sheet of paper has printed on it vertical strips of letters. On the left hand side is the representation of the Umkehrwalze (reflector), U.K.W. This contains two columns. The right hand of these is the entry and exit terminals, just the alphabet repeated. The left hand column contains the connection within the U.K.W. For instance the entry terminal A is connected to the Y terminal.

The column of letters on the background sheet on the right hand side represent the Stecker, (plugboard) connections. This column is overwritten with the Steckers entered into the Steckers text box.

The wheel strips contain a lower case alphabet on the right hand side, an upper case alphabet down the centre and the wheel wiring in lower case in the left hand column. The letter entered into this column is the letter to which it is connected on the right hand column.

The upper case alphabet down the centre represents the Ringstellung or tyre setting on the wheel. It is placed so that the Ringstellung letter on this strip is alongside the letter Z in the left hand column of the wheel.