INTRODUCTION
This page contains cumulative updates, revisions, and corrections to the
information in the SECOND EDITION of the book: "INSIDE ENIGMA" by Tom Perera
and Dan Perera; published in 2019. The SECOND EDITION contains almost twice as
much information as the first edition and over 150 additional
illustrations
Updates for the FIRST EDITION of the book may be found at:
http://EnigmaMuseum.com/enigma_book_updates.htm
Updates for the Enigma Library CD-ROM may be found at:
http://EnigmaMuseum.com/mecdcor.htm
New information about cipher machines is constantly coming to light as
historic government archives are declassified and studied by historians.
This information as well as corrections and revisions will be added to this
page as often as required.
There is a new edition of Dr. Ray Miller's book: The Cryptographic Mathematics of the Enigma
The new edition of his book is now available for viewing and download on the internet at:
https://www.nsa.gov/Portals/70/documents/about/cryptologic-heritage/historical- figures-publications/publications/wwii/CryptoMathEnigma_Miller.pdf?ver2019-07-31-064622-023
The book "Cryptology’s Role in the Early Development of Computer Capabilities in the United States"
Written by: James V. Boone and James J. Hearn in 2015 is available for viewing and download at:
https://www.nsa.gov/Portals/70/documents/about/cryptologic-heritage/historical-figures-publications/publications/cryptologys-role/cryptologys-role-in-the-early-development-of-computer-capabilities-in-the-united-states.pdf
Page 136.
Correct the end of the second sentence in the second paragraph to read:
"...used three 25-position electromechanical stepping switches that stepped around like Enigma rotors every time they received an electrical impulse from the keyboard."
Page 136.
Correct the next-to-last last sentence of the top figure caption on the right side of the page to read "This is a slightly simplified version of the NARA diagram showing the three 25-position, 20 layer stepping relays at the top and the 25 position, 6 layer stepping relay on the left."
Page 136.
Correct the first sentence in the caption of the middle figure in the right column to read: "This block of three 25-position stepping switches came from a Japanese Purple machine.
We have not provided a clear explanation and diagram explaining how the Enigma rotors are rotated.
Here is an explanation and some photographs:
EXPLANATION:
The Enigma rotors are moved by three pusher/levers that are activated by a metal frame whenever a key is pressed.
The rightmost rotor is rotated one step by its pusher/lever every time a key is pressed.
The middle rotor is rotated one step when a notch on the rightmost rotor allows its pusher/lever
to drop into its notch so that it is in position to step the middle rotor.
This step can be set to occur at any one of the 26 positions by setting the ring setting of the rotor
which sets its notch position.
So, the middle rotor steps once for every 26 steps of the rightmost rotor.
The leftmost rotor is rotated one step when a notch on the middle rotor allows its pusher/lever
to drop into its notch so that it is in position to step the leftmost rotor.
This step can be set to occur at any one of the 26 positions by setting the ring setting of the rotor
which sets its notch position.
So, the leftmost rotor steps once for every 26 steps of the middle rotor.
Three spring-loaded wheels press against the thumbwheel indentations of the rotors to stabilize them.
PHOTOGRAPHS:
(These photographs show an unrestored Enigma as it is disassembled for the first time.)
Here is a photograph of the metal frame that lies under the keyboard and is pushed down every time a key is pressed.
Here is another photograph showing the metal frame with the keyboard and light panel removed.
Pushing a keyboard key pushes down the front of this frame.
The frame pivots in the middle and causes the three pusher/levers in the back to move upwards.
Here is a photograph that shows the hinge that allows the metal frame to pivot down in front and up in back.
Here is a photograph showing the metal frame completely removed from the Enigma.
The three pusher/levers are visible at the back of the frame.
Here is a photograph showing the three pusher/levers that rotate the rotors when they are moved upwards by the metal frame.
Here is a closer view of the three pusher/levers that rotate the rotors:
Note that the rightmost pusher/lever is half the width of the other two.
This allows it to fit within the narrow space needed to advance the rightmost rotor on every keypress.
The other two (middle and leftmost) pusher/levers are double the width.
They ride on top of the shoulder of the rotor to their right until its notch allows them to drop down
to engage and advance their rotor.
Here is a photograph showing the three rubber (in some cases metal) wheels that press against the
thumbwheel indentations on a rotor and hold it firmly in place after it has been stepped by its pusher.
The levers that support these wheels do not move up or down.
They simply support the wheels that hold the rotors in position after their pusher/levers have rotated them.
SUMMARY:
Pushing a key pushes down the front of the metal frame.
The frame then pivots causing the rear of the metal frame with the three pusher/levers to rise upwards.
This upward movement causes the rightmost pusher/lever to rotate the rightmost rotor one step.
When the rightmost rotor has stepped to the position of its notch, the pusher/lever to the left
drops into its notch and causes the next rotor to the left to rotate one step.
When the middle rotor steps to the position of its notch, the left pusher/lever drops into its notch
and causes the next rotor to the left and to rotate one step.
The round rubber (or metal) indexing wheels do not move up or down.
They simply hold the rotors in place after the rotors have been pushed by their pusher/levers.
The new edition of his book is now available for viewing and download on the
internet at:
https://www.nsa.gov/Portals/70/documents/about/cryptologic-heritage/historical-
figures-publications/publications/wwii/CryptoMathEnigma_Miller.pdf?ver2019-07-31-064622-023
Page 197 - 9 May, 2019:
We inadvertently left out a very fine website by the late Tony Sale. It
covers a great deal of Enigma history and the work of the Polish and British
Codebreakers as well as the more advanced codebreaking work at Bletchley Park:
Tony Sale's Enigma History Website: http://codesandciphers.org.uk
Professor Emeritus Thomas B. Perera Ph.
D. and Dan Perera.
COPYRIGHT NOTICE: (Copyright (c) 2018: Prof. Tom Perera Ph. D. and Dan
Perera)
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