Homepage
Crypto
Index
Enigma
Hagelin
Fialka
Siemens
Philips
Nema
Racal
Motorola
STK
Transvertex
Gretag
HELL
Telsy
TST
Mils
AT&T
Tadiran
USA
USSR
UK
Voice
Hand
Mixers
Phones
Spy sets
Burst encoders
Intercept
Covert
Radio
PC
Telex
Agencies
Manufacturers
Donate
Kits
Shop
News
Events
Wanted
Contact
About
Links
Logo (click for homepage)
Codebooks
A codebook is a very old and effective method for concealing the contents of a message. Initially, codebooks were not meant for the encryption of a message, but simply to make the distribution of messages more efficient when using morse codes over telegraph lines or radio. In many cases, frequently used words or even complete sentences were replaced by three or five-letter abbreviations. This would make it easier (and cheaper) to send a message over a long distance. The international Q-Codes are a good example of this.

During WWII, codebooks were often used to encipher a message, sometimes in addition to other cryptographic methods, such as Enigma or hand ciphers. Cracking a codebook is a difficult task for a code breaker, but once the codebook is captured by the enemy, the secret is completely given away. They could therefore be classified as Security by Obscurity. On their own they aren't very safe, but when used in combination with other cipher methods, they can be a real nightmare for the average code breaker.
 
Internationales Signalbuch 1931
A good example of a very efficient codebook, is the German book shown here: Internationales Signalbuch 1931 (International Signals Book 1931) Band II, Funkverkehrsbuch (Volume II, Radio Traffic Book). It was published by Walter de Grunter & Co under the authority of the Reichsverkehrsministerium (National Traffic Ministery).

Before WWII, book like these were widely used for international (radio) traffic. More detailed images below.
  
Close-up of the title of the Internationales Signalbuch 1931

 
Close-up of the title of the Internationales Signalbuch 1931 The complete codebook of 1931. It is over 6 cm thick! A peek inside the codebook. It contains many chapters on special subjects. Close-up of a page from the codebook

 
Funkverkehrsheft
During WWII, the German Armed Forces used this book in addition to other cipher methods. It made messages shorter and hence more effecient, but also created an extra layer of obscurity in an encrypted message.

The full title of the book is Funkverkehrsheft für die Küstenverteidigung (Radio Traffic Book for Coastal Defence). It contains a number of entries that can be altered manually. The book shown here was used by the Germans for the defence of the Dutch coast. The names of cities and towns are written in the book by pencil.
  

 
Funkverkehrsheft courtesy Arthur Bauer [1]
 
Kriegsmarine Tables
During WWII, the German Kriegsmarine (Navy) used a variety of codebooks in combination with their M4 Enigma machine. The German Naval message procedures were very complex and caused the code breakers at Bletchley Park many headaches.
 
The images below show some German Navy code material, used during WWII.

The codebooks of the U-Boot department of the Kriegsmarine were printed with red water-solvable ink on pale red paper. When left behind in a sinking U-Boot, the codebooks would wipe themselves automatically, which is why it was so hard to capture them.

The caption on the top of the page on the right, reads: Vorsicht! Wasserlöslicher Druck! (Careful! Water solvable print!).
  

The procedures consisted of Enigma key settings, Kenngruppenbuch, Kengruppen tables, Letter-pair swap tables, Short Message books, Weather Code books, etc. Dirk Rijmenants in Belgium has described the procedures of the German Wehrmacht and Kriegsmarine in great detail on his website [2] .
 
Codebooks courtesy Arthur Bauer [1]
 
References
  1. Arthur Bauer, Foundation for German communication and related technologies
    Museum for historical German technology (mainly used before and during WWII).

  2. Dirk Rijmenants, Enigma Message Procedures
    Acurate descriptions of the Wehrmacht and Kriegsmarine Enigma procedures.

Further information

Any links shown in red are currently unavailable. If you like this website, why not make a donation?
Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Friday, 01 February 2013 - 15:04 CET
Click for homepage