ENIGMA
ENIGMA and its variants is a German electromechanical machine for message encryption whose use was widespread during the WW2.
It symbolizes the victory of the Allied code breakers, which can be estimated that their efforts have shortened the war by at least one year.
Many sites evoke the history and operation of this machine and we invite the visitor to also read this 92 pages PDF FILE made by students and well documented.
Unless you have deep pockets (at least 40 000 $) and lot of luck, the acquisition of a real old machine is a real utopia.
To revive this machine, there is no more than five solutions :
- Building it ! See still works on http://www.tatjavanvark.nl/index.html#works, it's absolutely amazing.
- One sheet of paper (yes it works) with data given on the website:
http://dave-reed.com/DIYenigma/index.html or
http://mckoss.com/Crypto/Enigma.htm
- Run a simulation on PC :
http://cryptocellar.org/simula/ or http://users.telenet.be/d.rijmenants/en/enigmasim.htm
and even an Excel spreadsheet :
http://chrisrae.com/programming/index.html
- Build a replica :
This kit is for sale on the Internet for € 130.00 excluding postage : http://www.cryptomuseum.com/kits
In the box are :
- A double-sided epoxy professional with metallized holes and silk screened.
- All necessary components with the programmed PIC microcontroller.
- Two-sided A3 sheets giving schematics and components locations.
- A 68 pages very comprehensive manual (in English). It includes step-by-step assembly of the circuit in the Heathkit style, for those who know. All is described step by step. There is also the description of a wooden box.
An entire chapter is devoted with great detail to the operation of the mechanical machine and its history. There are even examples of messages to decode !
In short, a remarkable work within reach of a neophyte but knowing handle a soldering iron and wire cutters.
The installation works from the last solder performed. It only remains to put in wooden boxe and possibly add some accessories.
This will be the subject of the following descriptions.
You have for download HERE a file containing all plans and current patterns.
POWER SUPPLY
The kit is designed to be powered by an AC adapter 8-12 V (not supplied) or batteries of 8-16 V (a 9 V batterie make also a good job but only for 6 hours !).
We chose to put the AA Ni-MH batteries inside the box and recharged by a small electronic assembly. The power socket (AC or DC) was placed on the right side of the Steckerbrett plate. Below, a red LED "Low Battery"indicator flashes to indicate when it's necessary to recharge the batteries.
An ON-OFF sub-miniature switch has been placed in the center of Steckerbrett in an unused mounting hole.
MORSE LISTENING
The mechanical Enigma machine does not directly produce a Morse code. Around the machine, there are two operators. The first simply type the letters of the message to be encoded one by one each time until the second operator has carefully noted the letter from the coding. This second message is then transmitted by a Morse operator.
In the electronic version, this step is integrated into the machine and you can hear the letters handled in Morse provided to add a buzzer or a low-frequency oscillator. One might even consider directly send the signal to a transceiver but it's strictly prohibited by law in some countries (encryption). Note that an RS232 output for connecting a PC in terminal mode or to connect two machines.
The RS232 socket has been placed to the left on the Steckerbrett and below, the green LED of the microcontroller was deported from its original location.
MECHANICAL ASSEMBLY
In our project, we have (unfortunately !) hid a lot of electronics.
Compared to the original installation, the display is raised to 6 or 7 mm with IC socket to put them at the same height as the cover letters that will help cover the whole by an horizontal plate (17 mm from the circuit ). Similarly, on the Steckerbret the components exceeding the height of integrated circuits (resistor network and decoupling capacitors) are soldered on the printed circuit back face.
A plate attached below the PCB by spacers supports batteries and Morse signal generator.
The chassis is perforated over the yellow LEDs Lampenfeld so as to illuminate the letters on their entire surface. As in the original, the letters are white on black (ink jet printing on a transparency or using mylar now supplied with the kit). A sheet of frosted plastic, also supplied, is placed against the mylar for uniform brightness across the letters.
Over the display a red filter enhances contrast.
The keys are a little mechanical problem. To keep things simple and make maximum use of standard products, we plan to use banana sockets and 4 mm outside diameter brass tube (3 mm inside) sold in lengths of 1 m at the DIY store ( In France : Leroy, Castorama, Briconautes, etc..). The banana sockets are eventually enlarged to 4.1 mm if the tube does not slide well and the base is incised with a fine tooth saw mill of 1.6 mm. This allows, with a piece of 1.5 mm brass piano wire set in the bottom of the tube, to provide anti-rotation key.
The hollow disk receiving the wafer is machined in a 12 mm brass rod, with an end mill of diam. 10 mm and a center hole of 4,1 mm.
The wafer are obtained with a cutter "home made" adapted to the inner dimension of the keys :
We also
conducted a "pasting table" for holding the keys on their axel at the
correct height during the hardening of Araldite glue. The letters are pasted on the final
assembly when completed, this to compensate for angular errors and to have
perfectly straight letters.
.... And is wired, tested, yet to make a wooden box.
FINAL ASSEMBLY
The wooden box was made of pine and varnished. In the bottom, we placed a miniature switch connected to the strap of the No. 2 jumpers dual row header. This lets you choose the operation with the Morse generation or RS232 output which will be discussed later.
In the
cover, twelve cords are provided for the possible links between the sockets of
Steckerbrett.
RS232 LINK
The serial link allows you to display on a computer terminal encoded characters or to connect two machines.The easiest way is to use HyperTerminal in Windows located at : All Programs / Accessories / Communications / HyperTerminal.
But there are other programs like RealTerm, TeraTerm, Termite, more or less sophisticated.