Cleave Books
trol = Teacher Resources on Line = trol
Index to Codes & Ciphers Material
For ease of use, this has been divided into sections as listed below, together with a brief description of their purpose and content. The [size] of each is given in kilobytes as guide to downloading times.
Each requires the use of an Acrobat Reader to allow it to be viewed and printed out.
[60 k]
Essential reading whether using just a part or the whole of this material. Includes a short vocabulary with some definitions, and a list of some well-known names in the history of cryptology. There is also list of further sources of information.
Scrambled Messages
[30 k]
How an ordinary message can re-arranged, in an orderly manner, so as to make it very difficult to read.
Buried Messages
[40 k]
Disguising a message so that it does not even look as though it contains any secrets.
Coded Messages
[20 k]
Using a code allows messages to be hidden and shortened at the same time.
Simple Cipher Messages
[70 k]
Hiding the messages by substituting other letters for those of the original text
Addition Ciphers
[20 k]
Using numbers and some simple arithmetic to hide a message
Multiplication Ciphers
[20 k]
How more complex arithmetic processes bury the messages even deeper.
Rotor Ciphers
[70 k]
Mechanical enciphering with a (very!) simplified paper model of the Enigma machine.
[40 k]
The science (or is it an art?) of breaking cipher messages, allowing them to be read without knowing the keyword or its equivalent.
Other Systems
[50 k]
Accounts of some other methods for creating ciphers.
Public Key Ciphers
[60 k]
How one particular modern cipher system (RSA) works, and can be made widely available to all, whilst retaining its security.
Additional Materials
[40 k]
While all sections contain their own support materials, this has a few more general items.
The Small Code Book
[40 k]
An abbreviated code book which can be printed out and assembled.
For use with Coded Messages (above).
Display Material
[70 k]
Diagrams suitable for making ohp slides or even projected directly onto a suitable screen or whiteboard.
The Gold Bug
[80 k]
The famous short story by Edgar Allen Poe about cipher breaking which was the first account to appear in a work of fiction.
The Dancing Men
[80 k]
The story of how Sherlock Holmes broke a symbol cipher.
The Enigma Machine
[50 k]
Picture of the most well-known ciphering machine
The SIGABA Machine
[330 k]
Picture of the US equivalent of the Enigma machine.
The British TypEx machine was similar to this one.
The Hagelin Machine
[80 k]
Picture of the Hagelin M209 machine.
This was a portable (purely mechanical) enciphering machine.
[20 k]
Available yes, but a password will be needed to read this file.

The copyright in all of this material belongs to the originators who created it.
The material is made available here for downloading and dissemination for

Go to the topthe trol index page