A British

voice encryption Secure voice (alternatively secure speech or ciphony) is a term in cryptography for the encryption of voice communication over a range of communication types such as radio, telephone or IP. History The implementation of voice encryption date ...

device used with (for example)

Larkspur radio system Larkspur was the retrospectively adopted name of a tactical radio system used by the British Army. Its development started in the late 1940s with the first equipment being issued in the mid-1950s. It remained in service until replaced by Clansman ...

sets. BID means 'British Inter Departmental'. These systems or equipment types were generally used by more than one single governmental agency or department. The authority for BID's was the

Communications-Electronics Security Group Government Communications Headquarters (GCHQ) is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the United Kingdom. Primaril ...

(CESG) who were part of

Government Communications Headquarters Government Communications Headquarters (GCHQ) is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the United Kingdom. Primari ...

(GCHQ). The BID/150 speech encryption key generator is a single channel device for use with the British Army C42 and C45

. This was the first Combat Net secure speech system whose key was set through the use of punch cards within the device. Examples of the BID/150 are on display at the Royal Signals Museum,

Blandford Forum Blandford Forum ( ) is a market town in Dorset, England, on the River Stour, Dorset, River Stour, north-west of Poole. It had a population of 10,355 at the United Kingdom 2021 census, 2021 census. The town is notable for its Georgian archit ...

. It was first used operationally by the 15th Signal Regiment during the Aden crisis in the late 1960s and was widely used from battalion level up to corps headquarters. It remained in use until the early 1980s. In secure mode the analogue speech signal is digitized, then encrypted by combination with the digital key generated by the BID/150; the digital stream is then fed to the transmitter, to pulse modulate the carrier. On receive, the sequence is reversed. Good radio performance was needed for reliable secure working. To this end, vehicles carrying the C42-DM-BID/150 system were issued with a 27-foot mast and an elevated antenna. The set carried a 'Goodman Box', to check signal strengths and antenna performance. The operator had searching set-up and performance drills to be strictly followed.

External links

Crypto Machine Website

Royal Signals Museum, Blandford Forum
Secure communication {{crypto-stub