The BID 770 was a British-built electronic

cryptography Cryptography, or cryptology (from grc, , translit=kryptós "hidden, secret"; and ''graphein'', "to write", or ''-logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adve ...

device, codenamed TOPIC. It was also used by Canada's foreign service under the codename TENEC. TOPIC was brought into service in 1977, and became obsolete in 1995. TOPIC was used to protect telegraph traffic, and replaced the earlier mechanical system called

ROCKEX Rockex, or Telekrypton, was an offline one-time tape Vernam cipher machine known to have been used by Britain and Canada from 1943. It was developed by Canadian electrical engineer Benjamin deForest Bayly, working during the war for British Se ...

. It could be operated in both on- and off-line modes. Weighing 65 lb, the machine used

diode–transistor logic Diode–transistor logic (DTL) is a class of digital circuits that is the direct ancestor of transistor–transistor logic. It is called so because the logic gating function (e.g., AND) is performed by a diode network and the amplifying functio ...

instead of single transistors.

External links

Jerry Proc's page on the BID 770
{{Cryptography navbox , machines Encryption devices