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History of the Enigma Machine

The Enigma cipher machine was a device developed in Poland prior to World War II. It allowed for, at the time, a reasonable level of security in data transmission. It was thought at the time that it was an unbreakable cipher, and as happens all too often, it wasn't.

The heart of the machine was a set of rotating wheels. These wheels had contacts on the two sides around the edge that allowed electrical contact to be routed through the wheels. Each letter was represented on the wheels, and an electrical signal was passed through each of the left hand side contacts for a given letter to a different right hand side contact.

These wheels where then stacked side by side on a common shaft and where then placed between a frame an a thing called a "reflector". The reflector had electrical contacts around it's left side, just like the wheels. But it differed in that instead of connecting the right side to the left, it simply rerouted the left side signals for a given letter position back to some other left side contact.

The machine worked by converting a key stroke into an electrical signal that then went into a corresponding contact on the far left frame. This then made contact with the first wheel, say A, and was rerouted through the wiring of the wheel into say a T. The signal then left the right side of wheel 1, to enter the left hand side of wheel 2 at position T. The signal would then map through wheel 2, starting at position T and come out as position V. This would go on through three or four wheels, depending on what time during the war you are talking about, until it hit the reflector. The reflector would reconnect the signal and ship it back through the wheel set until it came out of the left hand side of wheel 1 in a position other than the one it came in on. Because of the one to one mapping through all of the wheels, and the reflector, this is guarenteed by the design.

Once out of the wheels, the signal would then go through a thing called the plug board. This flipped pairs of characters around in a fixed way. Later analysis of the Enigma machine proved this to be one of the best features of the device. By forcing particular characters to always be flipped in the last stage, it made the rotor selections far harder to determine.

In any case, once the signal left the plug board, it entered an array of lamps that were set behind letters to illuminate. The final operation that the Enigma then performed was to rotate the wheels. It did this in a fairly simple clock like motion (rotate the first wheel 26 times, then rotate the next wheel once; when the second wheel had been rotated 26 times, rotate the third). This made the translation of two subsequent characters operate off of different wheel settings, thus making it very hard to decrypt the message.

Because of the reflector, if you put in a "C" and it comes out as a "T" for any one wheel setting, you can also put in a "T" and get out a "C". This was a simplicity that worked well for this machine. You didn't have to care about whether you were encoding or decoding. You just had to setup the machine right prior to the attempt.

The operation crew for this device usually consisted of three folks. One would read (or receive it by Morse Code off of the radio) the input text to be encoded or decoded and type it into the Enigma. One would read off the lamps and the last person would write the resulting text down or transmit it via Morse Code to the receiving party. This made duty in the signal corps fairly hazzardous, in that to encode or decode any one message, there were three guys, all heads-down working on the message. All of them had their hands full, and as such, didn't have hands for weapons to defend themselves.

Each day, the Enigma operators had a setting for the machine to start all messages on. This setting included which of the wheels to use, where they should "start", and what the plug board settings should be for the day and hour that you were transmitting the message. Relying on this human interaction with the machine helped break the Enigma cipher. Operators would get lazy, and as they typically knew the guy on the other end of their message, they would come to a mutual understanding on what they would simplify.

In any case, a group of mathemeticians at Blechy Park in England broke the Enigma Cipher with a machine that they built called "the bomb". It was basically a series of wheels that dealt with all of the perumutations of the wheels. Given an Enigma machine with 3 wheels, the bomb used 5 wheels (one for each possible starting wheel), and each wheel's output would then go to a set of 4 wheels (having removed the first one from the resulting set) and when would try to do the whole thing over. The British team used paper tape telegraph machines to print out the text rather than the light pannels that the Germans used. Scores of people would then stare at the paper tapes and would wait for reasonable German words to come out. The first tape to indicate valid German would then be referenced back to figure out what the settings for the original Engima was that encoded the message. This would be recorded with the original start time for further research.

This is where the Blechy Park team got some of their early breaks. That human interaction between the German signal corps Enigma operators came back to haunt them. The logs of what the starting state of the Enigma machines was proved to indicate which German operators were "simplifing" their machine's setups. Using the information about how they simplified things, allowed the British team to zero in on the starting state of a given Enigma machine's operational settings were for any one given day and operator.

All of this, of course, is history. The Enigma cipher machine is now a thing of antiquity. As an encryption mechanism, the Enigma is now very out of date. Modern computers can easily do a brute force attack on correctly encoded Enigma ciphers and come up with the plain text rather easily. However, as one of the first encryption mechanisms used in a warfare setting, the Enigma machine has the distinction of being one of the most costly devices ever built.

Enigma Example

Let's encode the message "Hello Sam". To be true to the original Enigma machine, all letters must be upper case and if any spaces or punctuation is needed, it must be spelled out. In our case, our message would become "HELLOSAM". Next, we would take one character at a time and pass them through the wheels given below:

Wheel 1

Current Setting = 0
Forward Index Reverse
A 2 0 8 A
B 23 1 4 B
C 25 2 0 C
D 7 3 9 D
E 1 4 25 E
F 10 5 23 F
G 14 6 12 G
H 13 7 3 H
I 0 8 17 I
J 3 9 20 J
K 11 10 5 K
L 18 11 10 L
M 6 12 13 M
N 12 13 7 N
O 15 14 6 O
P 22 15 14 P
Q 19 16 21 Q
R 8 17 22 R
S 21 18 11 S
T 24 19 16 T
U 9 20 24 U
V 16 21 18 V
W 17 22 15 W
X 5 23 1 X
Y 20 24 19 Y
Z 4 25 2 Z
Wheel 2

Current Setting = 0
Forward Index Reverse
A 3 0 24 A
B 2 1 3 B
C 24 2 1 C
D 1 3 0 D
E 4 4 4 E
F 8 5 22 F
G 11 6 16 G
H 21 7 8 H
I 7 8 5 I
J 25 9 19 J
K 10 10 10 K
L 13 11 6 L
M 19 12 20 M
N 23 13 11 N
O 22 14 23 O
P 15 15 15 P
Q 6 16 17 Q
R 16 17 25 R
S 20 18 21 S
T 9 19 12 T
U 12 20 18 U
V 18 21 7 V
W 5 22 14 W
X 14 23 13 X
Y 0 24 2 Y
Z 17 25 9 Z
Wheel 3

Current Setting = 0
Forward Index Reverse
A 23 0 4 A
B 2 1 21 B
C 21 2 1 C
D 18 3 16 D
E 0 4 23 E
F 24 5 9 F
G 6 6 6 G
H 22 7 13 H
I 9 8 15 I
J 5 9 8 J
K 10 10 10 K
L 20 11 25 L
M 12 12 12 M
N 7 13 19 N
O 15 14 24 O
P 8 15 14 P
Q 3 16 17 Q
R 16 17 18 R
S 17 18 3 S
T 13 19 22 T
U 25 20 11 U
V 1 21 2 V
W 19 22 7 W
X 4 23 0 X
Y 14 24 5 Y
Z 11 25 20 Z
Reflector

N/A
 
1
0
3
2
5
4
7
6
9
8
11
10
13
12
15
14
17
16
19
18
21
20
23
22
25
24

'H' would map to 7 and go into the first wheel. '7' would become '13' going forward through wheel 1. '13' would become '23' going forward through wheel 2. '23' would become '4' going forward through wheel 3. The reflector would convert '4' to '5'. '5' would become '9' going back through wheel 3. '9' would become '19' going back through wheel 2. '19' would become '16' going back through wheel 1. This would result in mapping 'H' into 'Q'. Now we rotate wheel 1. The resulting wheel settings look like:

Wheel 1

Current Setting = 1
Forward Index Reverse
A 22 0 3 A
B 24 1 25 B
C 6 2 8 C
D 0 3 24 D
E 9 4 22 E
F 13 5 11 F
G 12 6 2 G
H 25 7 16 H
I 2 8 19 I
J 10 9 4 J
K 17 10 9 K
L 5 11 12 L
M 11 12 6 M
N 14 13 5 N
O 21 14 13 O
P 18 15 20 P
Q 7 16 21 Q
R 20 17 10 R
S 23 18 15 S
T 8 19 23 T
U 15 20 17 U
V 16 21 14 V
W 4 22 0 W
X 19 23 18 X
Y 3 24 1 Y
Z 1 25 7 Z
Wheel 2

Current Setting = 0
Forward Index Reverse
A 3 0 24 A
B 2 1 3 B
C 24 2 1 C
D 1 3 0 D
E 4 4 4 E
F 8 5 22 F
G 11 6 16 G
H 21 7 8 H
I 7 8 5 I
J 25 9 19 J
K 10 10 10 K
L 13 11 6 L
M 19 12 20 M
N 23 13 11 N
O 22 14 23 O
P 15 15 15 P
Q 6 16 17 Q
R 16 17 25 R
S 20 18 21 S
T 9 19 12 T
U 12 20 18 U
V 18 21 7 V
W 5 22 14 W
X 14 23 13 X
Y 0 24 2 Y
Z 17 25 9 Z
Wheel 3

Current Setting = 0
Forward Index Reverse
A 23 0 4 A
B 2 1 21 B
C 21 2 1 C
D 18 3 16 D
E 0 4 23 E
F 24 5 9 F
G 6 6 6 G
H 22 7 13 H
I 9 8 15 I
J 5 9 8 J
K 10 10 10 K
L 20 11 25 L
M 12 12 12 M
N 7 13 19 N
O 15 14 24 O
P 8 15 14 P
Q 3 16 17 Q
R 16 17 18 R
S 17 18 3 S
T 13 19 22 T
U 25 20 11 U
V 1 21 2 V
W 19 22 7 W
X 4 23 0 X
Y 14 24 5 Y
Z 11 25 20 Z
Reflector

N/A
 
1
0
3
2
5
4
7
6
9
8
11
10
13
12
15
14
17
16
19
18
21
20
23
22
25
24

Then we would encode "E". 'E' would map to 4 and go into the first wheel. '4' would become '9' going forward through wheel 1. '9' would become '25' going forward through wheel 2. '25' would become '11' going forward through wheel 3. The reflector would convert '11' to '10'. '10' would become '10' going back through wheel 3. '10' would become '10' going back through wheel 2. '10' would become '9' going back through wheel 1. This would result in mapping 'E' into 'J'. Now we rotate wheel 1.

Continuing on in this vein, the resulting encoding of "HELLOSAM" would be: "QJIYZLTY".

I would also like to point out here that each time you reload this page, new wheels are generated and actual encryption occurs. However, as I do not give any way to interact with what is encoded, this page serves only as an educational tool.

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The website "Redline" by Roland J. Stolfa is licensed under a Creative Commons Attribution-ShareAlike 3.0 United States License.
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