Army Enigma Comic Strips, Rod and Alphabet Squares
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
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
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.