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Enigma help file.

Contents

Background

Enigma Principles

Operating Procedure

Program controls

Program introduction

Mouse and Keyboard functions

Machine menu

Settings menu

Window menu

View menu

Edit menu

File menu

Options menu

Tools menu

Help menu

Glossary - English and German

Further reading


Program Introduction

This help file descibes the operation of a series of Enigma cipher simulators.

Some models of the simulator will not have all of the menu fuctions described here.

Each variant of the Enigma cipher has been given a separate simulator program  to highlight the differences that exist in this family of cipher machines.

The main Services simulator can be switched between the 3-wheel Army / Air Force machine and the three and four wheel Naval machines. This is achieved from a menu option. This program can also be started in a chosen mode by using a command line switch. The command line switch options are:

/a	3 wheel Army / Air Force

/3	3 wheel Naval

/4	4 wheel Naval

/e	Enables the Tools menu

The /e switch can be used in addition to any one other switch.

If a machine switch is not given then the simulator will start off in the last previously used mode .


Mouse and Keyboard functions.

Keyboard operation.

The Enigma keyboard in the main window can be operated by selecting the on screen keys with the left mouse button. The PC keyboard characters A-Z can also be used to operate the Enigma keyboard.  The input text appears in the Message in window and the resultant enciphered text is placed in the Message out window.

Key 'T' pressed, enciphered to 'J'

The main window will only receive  keyboard input when it has the input focus. To set the main windows as the focus window either select it with the mouse or select Enigma from the Window menu.

The PC keyboard character '-' (hyphen) is also accepted as input to the simulator and is intended to allow unknown cipher text characters to be entered to give a clean looking output display:

Cipher:	QNB-F JWMJI RYNGV OPKVN

Plain:	WET-E RVORH ERSAG EYYNU

The maximum message length that can be enciphered by the simulator is 4000 characters, this is somewhat larger than the recommended maximum Enigma message length of 180 characters.

Setting the wheel positions.

The mouse can be used to set the wheel ground positions. Each wheel can be moved by selecting its thumbwheel with the mouse, either below or above  the center line to move it forward or reverse. For the Army/Air Force machine the cover must first be opened by selecting it with the mouse.

A quick method of Setting the wheel positions.

To quickly set a particular wheel position, hold down the left mouse button over the window, then enter the required wheel position (A-Z) from the PC keyboard, whilst keeping the mouse button depressed.

To quickly set all 3 wheels (or 4 in the case of the M4) first hold down the mouse somewhere between the lampboard  and wheels ( but avoiding the thumbwheels ) and then type in the required 3 (or 4) letters from the PC keyboard.

When the wheel positions are set by any of these methods, their positions will be remembered by the program. Selecting Reset will return the wheels to these remembered positions.

The Red and Green markers in the wheel windows do not appear on the real machines, they are used in the simulators to indicate the approach and position of a turn over point. The green marker indicates the wheel position at which the notch is engaged.


Background

The German Enigma is probably the best known of the WW2 cipher machines used by either side of the conflict.

Invented in 1918, it was developed as both a commercial and military encipherment system before and during the war.

Enigma is an electro-mechanical device that utilizes a stepping wheel system to 'scramble' a plaintext message to produce a ciphertext message via polyalphabetic substitution.

The number of ciphertext alphabets is astronomically large - a fact that led the German military authorities to believe, wrongly as it turned out, in the absolute security of this cipher system.


Enigma - principle:

Enigma's output is a very complex polyalphabetic substitution ciphertext. The Enigma machine consists of a number of components.

A message to be enciphered is input from a keyboard - QWERTZU layout. The signal leaves the keyboard and passes through a plugboard where, if the plugboard socket contains a connector, its identity is switched in a monoalphabetic substitution. If the particular socket does not contain a plug, the identity of the input character is unchanged.

From the plugboard the signal then passes to the entry stator which passes it to the first of a series of three wheels.

Each of these wheels has twenty-six contacts on each of its faces, cross-wired in a random fashion so that the identity of an incoming character is changed three times as it passes through the three wheels, which are in electrical contact each with its adjacent wheel.

With each keyboard input the extreme right-hand wheel moves one position. Additionally, once during a complete revolution of a wheel, the wheel to its left steps once.

After passing through the three wheels the signal reaches the reflector which performs two functions - it changes the signal's identity once more and also sends it back, in the reverse direction, through the three wheels to the entry stator.

From here it passes back to the plugboard and then to the lampboard where a lamp corresponding to the now enciphered character is illuminated.

Note the bi-directional nature of the plugboard's substitution process and also the fact that, because of the reflector's function in the encipherment process, no plaintext character can ever encipher to itself. These two weaknesses in the system were to be exploited to great effect by the allied cryptanalysts.


Procedure:

The Enigma operator had to set up his machine according to whatever procedural instructions prevailed at the time by adjusting the following parameters.

Select three wheels from a set of five in the case of the Army and Air Force machines or from a set of eight in the case of the Naval machines†.

Set the Ringsetting on each wheel and arrange these wheels on the machine's spindle in the order prescribed in the daily, or other periodic, instructions for machine initialization.

Set up the plugboard according to the same instructions. Normally, ten sets of plugs were used leaving six letters 'self-steckered'.

Close the internal lid of the Enigma and manually set the wheels to the daily Groundsetting.

Enigma was then ready for use.

† In the case of the M4 it was also necessary to select the fourth wheel, Beta or Gamma and a corresponding 'thin' reflector 'B' or  'C'.


Machine

The Machine menu selects the model of Enigma to be used. The choices are:

A: Standard three-wheel Army/Air Force machine.

A17119 is a late model machine. Its identity plate showing that is was manufactured in 1943.

A

17119 S/jla/43

There are five wheels [ I, II, III, IV, V ] from which to make the selection. The wheels are marked with numbers [01 - 26] on the outer ring. Two reflectors are available [B, C] together with a full complement of thirteen plugs. Access to the thumbwheels is gained by raising the top cover, either by 'clicking' on it or via the View menu.

M3: The three-wheel Navy machine.

M2114 is an early example of the type and displays the numerals [0 - 9] on the top row of the keyboard. This is characteristic of early M3 and M4 Navy machines which was absent in later models.

There are eight  wheels [ I, II, III, IV, V, VI, VII, VIII ] from which to select three. Navy wheels are marked with letters [A - Z] on the outer ring. Two reflectors [B, C] and thirteen plugs are also available with this machine.

M4: The four-wheel Navy machine.

M18321 is a late model M4. Its identity plate showing that is was manufactured in 1944.

M

Na 220 900

18321 /aye/ 44

There are eight normal wheels available [I - VIII] together with a choice of two 'Greek' wheels [Beta and Gamma] and their corresponding 'thin' reflectors [B and C]. Thirteen plugs are available for the plugboard.

After a machine has been selected clicking on Info will provide details of the selection.


Inner Settings

The Inner settings dialogue is used to select the wheel order, reflector and ring settings.

Wheel order.

The wheels available for the current machine will be listed in the list boxes. The current settings are shown highlighted [ II - III - I ]. If an error is made in the selection, for example the same wheel is chosen for more than one position, then a warning message box is displayed. The error must be corrected before proceeding.

If the machine type selection is changed and a wheel is installed that is not usually available for the chosen machine, then the Inner Setting dialogue box is automatically displayed with the unavailable wheel positions left blank. You should then select the required wheels from the list box which will now contain all available wheels for the chosen machine.

Ring settings (Ringstellung).

The ring setting can either be entered as letters (A-Z) or as numbers (1-26)

If an error is made in selecting the Ring Settings then a warning message box is displayed. The error must be corrected before proceeding.

Reflector (Umkehrwalze)

For each machine, a list of the available reflectors is shown in the list box.

The four - wheel  Naval machine has a special set of 'thin' reflectors that are used in conjunction with the extra fourth 'greek' wheel.

Stecker:

The Stecker dialogue box allows the stecker board connections to be specified. The stecker connections are entered as pairs of letters in one of the 13 text input boxes.

The letter pairs may be entered in any order. If an error is made in the selection then a warning message box will be displayed. The usual errors are a letter used twice or a missing letter. The Clear button can be used to erase all the selections.

The Cancel button can be used to ignore any changes - the previous stecker connections will then be retained.

The number of steckered connections in use depended on the procedures that prevailed at the time but was typically 10 with 3 pairs left unsteckered.

Reset

Sets all wheel positions to the previous starting positions.

Freeze wheels

Enciphers the keyboard input without advancing the wheels.

Fast wheel only

Enciphers the keyboard input and only advances the 'fast' right wheel.


Window:

Selects the operating window.

Arrange all

Allows the main Enigma window and both message windows to be displayed at the same time.

1 Scrambler [default]

Displays, dynamically, the signal path through the Enigma from the keyboard input to the lampboard illumination. The #1 option may be changed to display the signal path behaviour within the plugboard, an individual wheel or the reflector via the options in the View menu.

2 Enigma

Selects the main Enigma window. This is necessary to enable operation of the machine with mouse or computer keyboard input.

3 Message Out

Selects the Message Out window. This is necessary to enable the File and Copy menu options.

4 Message In

Selects the Message In window. This is necessary to enable the File and Copy menu options.


View:

Selects which component of the Enigma signal path is to be viewed with the '1' option under the Window menu. The choices are:

Scrambler:	The entire signal path from the keyboard to the lampboard.

Stecker:	The signal path through the plugboard.

Right:	The signal path through the 'fast' wheel.

Middle:	The signal path through the 'middle' wheel.

Left:	The signal path through the 'slow' wheel.

Greek:	The signal path through the Beta or Gamma wheel [M4 only].

Reflector:	The signal path through the reflector.

In some wiring views the red colour coded connection is the signal path passing through the scrambler towards the reflector, the blue connection is the return signal path back out towards the lampboard.


Edit:

Allows the text within the Message In and Message Out windows to be transferred to or from the clipboard:

Copy

Copies the selected text from either Message window to the clipboard.

Paste

Pastes the clipboard contents into either Message window.

The pasted text replaces all previous text in the window.

Select all

Selects all the text in the window.

Text can also be selected by dragging with  the mouse.


File:

Message window file operations.

The files created by the simulator are plain ASCII with embeded spaces to separate the groups. The files also contain carriage return and line feed characters to allow them to be conveniently examined using a text editor.

The simulator will also accept plain ASCII text files created with a text editor program. Embeded spaces and newline characters will be ignored, the text will be formatted in the receiving window according to the Group setting.

Open Pt....

Opens a plaintext [*.pln] or other file for the selected Message window.

Open Ct....

Opens a ciphertext [*.cyp] or other file for the selected Message window.

Save Pt as....

Saves the selected Message window as a plaintext [*.pln] file to disk.

Save Ct as....

Saves the selected Message window as a ciphertext [*.cyp] file to disk.

Print....

Sends the contents of the selected Message window to the printer.

Print Pt-Ct....

Prints the machine start settings, followed by the plaintext  and the ciphertext.

Print Setup....

Sets the printer options.

Exit

Quit Enigma program.


Options:

Encipher Text....

Enciphers [or deciphers] the text in the Message In window and places the resultant text in the Message Out window.

Fast encipher allows a long message to be enciphered/deciphered  without updating the wheel display or message windows. On completion of the message, the wheels will be set to their final position and the Message out window will display the enciphered [or deciphered] text.

Slow encipher shows the wheel movement as each character is processed.

The message length is shown in the Message window title bar.

Clear Message In

Clears all text from the Message In window.

Clear Message Out

Clears all text from the Message Out window.

Lamp filter

Toggles the green lampboard filter on/off. The Lamp filter is a green celluloid sheet that is placed over the lamp board to reduce eye strain in bright sunlight.

Sound

Toggle the sound on/off.

When the sound is on, a wave file [.WAV] is played when any Enigma key is operated and released. This function will only operate if a sound card is installed in the PC.

Group 4

Sets the text display groups to a length of four characters. [default type M3 and M4].

Group 5

Sets the text display groups to a length of five characters.  [default for type A].

Scheme 1/2/3

Selects the background color and contrast of the machine panel.


Tools:

Useful items for Enigma researchers.

Print Map....

Prints the alphabetic substitution mapping for the first forty wheel positions starting from the current wheel setting.

Machine Period

Displays the first ten and the last three wheel settings for the entire cycle period.

This allows the machine period to be established together with any possible one or two 'lead in' positions.

Crab

Searches for 'crabs' and 'lobsters', for one complete machine period and lists the results in a text file.

Female....

Searches for the occurence of 'females' for a specified machine period and lists the results in a text file. There is an option to search with fixed wheels and random keys or free running wheels and random keys.


Help:

Help

This file.

About....

Copyright notice and credits.


Further reading:

Books

Deavours, C.A. Breakthrough '32 - The Polish Solution of the Enigma. Agean Park Press, 1988.

Deavours, C.A. and Kruh, L. Machine Cryptography and Modern Cryptanalysis. Artech House, 1985.

Enever, T. Britain's Best Kept Secret. Sutton Publishing, 1996.

Garlinski, J. The Enigma War. Scribners, 1979.

Hinsley, F.H. and Stripp, A. (Eds.) Codebreakers, The Inside Story of Bletchley Park.  Oxford, 1993.

Hodges, A. Alan Turing: the Enigma. Vintage, 1992.

Kahn, D. Seizing the Enigma. Houghton-Miffin, 1991.

Kozaczuk, W. Enigma. Univ. Pub. of America, 1985.

Welchman, G. The Hut Six Story. M & M Baldwin, 1997.

West, N. GCHQ The Secret Wireless War 1900-86. Weidenfeld & Nicolson, 1986.

For Young People

Reynard, R. Secret Code Breakers II. Smith and Daniel, 1997.

Articles

Erskine. R. Naval Enigma: A Missing Link. Int. J. of Intelligence and Counterintelligence, Vol. 3, No.4.

Erskine, R. and Weierud, F. Naval Enigma: M4 and Its Rotors. Cryptologia, Vol. XI, No. 4 1987.

Hamer, D. H. Enigma: Actions Involved in the 'Double Stepping' of the Middle Rotor. Cryptologia, Vol. XXI, No. 1 1997.

Miller, A.R. The Cryptographic Mathematics of Enigma. Cryptologia, Vol. XIX, No. 1 1995.

Rejewski, M. How Polish Mathematicians Deciphered the Enigma. Annals of the History of Computing, Vol.3, No.3 1981.

Fiction

Harris, R. Enigma. Random House, 1995.


Glossary: English and German

BP - Bletchley Park

Decipher - transform a cipher text into plain language

Eintrittwalze - entry wheel (stator)

Encipher - transform a plain language text into cipher.

Greek  - wheels Beta and Gamma [for obvious reasons] used in the M4

Grundstellung - groundsetting

Machine period - number of keystrokes for a complete machine cycle

Ringstellung - ringsetting

Rotor - wired wheel [wheel was commonly used at BP]

Scrambler - consists of the entry stator, moving wheels and the reflector.

Self-steckered character - a letter that is not 'switched' in the plugboard

Stecker - plug

Steckerbrett - plugboard [sometimes referred to as 'steckerboard']

'Thin' reflectors - reflectors used with the 'Greek' wheels of the M4.

Umkehrwalze - reflector

Walzen - wheel

Walzenlage - wheel order