Slidex was a hand-held, paper-based
encryption
In Cryptography law, cryptography, encryption (more specifically, Code, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. This process converts the original representation of the inf ...
system used at a low, front line (platoon, troop and section) level in the
British Army
The British Army is the principal Army, land warfare force of the United Kingdom. the British Army comprises 73,847 regular full-time personnel, 4,127 Brigade of Gurkhas, Gurkhas, 25,742 Army Reserve (United Kingdom), volunteer reserve perso ...
during the Second World War and later the
Cold War
The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
period. It was replaced by the
BATCO
BATCO, short for Battle Code, is a hand-held, paper-based encryption system used at a low, front line (platoon, troop and section) level in the British Army. It was introduced along with the Clansman combat net radio in the early 1980s and was la ...
tactical code, which, in turn has been largely made obsolete by the
Bowman secure voice radios.
Design
Slidex used a series of vocabulary cards arranged in a grid of 12 rows and 17 columns. Each of the 204 resulting cells has a word or phrase, as well as a letter or number. The latter allowed the system to spell out words and transmit numbers.
The cards were stored in a folding case that had a pair of cursors to facilitate locating cells. Messages were encrypted and decrypted using code strips that could be placed in holder along the top and left side of the vocabulary card. Blank vocabulary cards were provided to allow units to create a word set for a specific mission.
See also
*
Encryption algorithm
In cryptography, encryption (more specifically, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. This process converts the original representation of the information, known as plain ...
*
Military intelligence
Military intelligence is a military discipline that uses information collection and analysis List of intelligence gathering disciplines, approaches to provide guidance and direction to assist Commanding officer, commanders in decision making pr ...
Further reading
* "The Slidex RT Code", ''Cryptologia'' 8(2), April 1984
References
Photographs and description of Slidex
{{crypto-stub
History of cryptography
Military communications of the United Kingdom