The 120 machines, the U.S. Navy’s Cryptanalytic Bombes, were seven feet high, two feet wide, and ten feet long. Each one weighed 5,000 lbs. The following photo with one of the WAVES in front of the machine gives an idea of the size of the machine. In person I find it intimidating.
US Navy Cryptanalytic Bombe
The front and back of the Bombes each had eight columns of four rotors. The top wheel mimicked the Enigma’s new fourth rotor while the bottom commutator represented the rightmost, or fastest, rotor of the Enigma. The bottom rotor spun at a speed of approximately 1,725 revolutions per minute, which allowed the machine to complete its run in only twenty minutes.
A closeup of the Bombe from the front, taken by the Navy, with parts labelled
Right-click the image and open in a new window for a full page size view.
Rearview of the bombe, parts labelled. Never fails to amaze me.
Much reliable information can be found in a booklet written by Jennifer Wilcox, Assistant Curator at the National Cryptologic Museum. The text of this booklet can be found History of the Cryptanalytic Bombe.
There is much new information about the US Bombe online now. One site which has really explained a great deal to me is US Navy Cryptanalytic Bombe – A Theory of Operation and Computer Simulation, an analysis written by Magnus Ekhall and Fredrik Hallenberg. I did not realize until I read this how shallow my understanding of the bombe in operation was.
The Bombe currently on display at the Nat’l Crypto Museum
Because so much excellent information is available through the NSA web site, I have taken the liberty of reproducing their index here. I recommend their publications as a primer of documented facts. PDF or text file versions are available for most of the monographs and brochures. Printed copies of publications marked with an asterisk (*) may be requested from the Center for Cryptologic History via email at history@nsa.gov. Rather than include links with this list that can become outdated I’ve just listed the titles. All links can be found at the Publications Index Page. (This link frequently changes; just search for “Center for Cryptologic History publications”)
| Subject | Title | Author | Date |
|---|---|---|---|
| Bombes | The Secret of Adam and Eve | Jennifer Wilcox | 2003 |
| Cipher Machines | German Cipher Machines of World War II * | David Mowry | 2003 |
| Code Talkers | Origins of the Navajo Code Talkers | Patrick Weadon | 2002 |
| COMINT | A History of US Communications Intelligence during WWII: Policy and Administration | Robert Louis Benson | 1997 |
| Enigma | The Cryptographic Math of the Enigma | Dr. A. Ray Miller | 2019 |
| Enigma | The First Americans: The 1941 US Codebreaking Mission to Bletchley Park | David Sherman | 2016 |
| Enigma | Solving the Enigma-History of the Cryptanalytic Bombe | Jennifer Wilcox | 2001 |
| Mathematics | How Mathematicians Helped Win WWII | John Clabby | 2005 |
| Holocaust | Eavesdropping on Hell: Historical Guide to Western Communications Intelligence and the Holocaust, 1939-1945 | Robert Hanyok | 2004 |
| Mathematics | How Mathematicians Helped Win WWII | John Clabby | 2005 |
| Midway | The Battle of Midway: AF is Short of Water | Patrick Weadon | 2000 |
| Pearl Harbor | Pearl Harbor Revisited: United States Navy Communications Intelligence, 1924-1941 | Frederick Parker | 1994 |
| Pearl Harbor | West Wind Clear: Cryptology and the Winds Message Controversy – A Documentary History * | Robert Hanyok and David Mowry | 2008 |
| SIGSALY | A History of Secure Voice Coding: Insights Drawn from the Career of One of the Earliest Practitioners of the Art of Speech Coding | Joseph P. Campbell, Jr., and Richard A. Dean | 2001 |
| SIGSALY | SIGSALY Story | Patrick Weadon | 2000 |
| SIGSALY | The Start of the Digital Revolution: SIGSALY – Secure Digital Voice Communications in WWII * | J. V. Boone and R. R. Peterson | 2000 |
| War in the Pacific | The Quiet Heroes of the Southwest Pacific Theater: An Oral History of the Men and Women of CBB and FRUMEL * | Sharon A. Maneki | 1996 |
| War in the Pacific | A Priceless Advantage: U.S. Navy Communications Intelligence and the Battles of Coral Sea, Midway and the Aleutians * | Frederick D. Parker | 1993 |
| Women | Sharing the Burden: Women in Cryptology during WWII * | Jennifer Wilcox | 1998 |