The Enigma crypto machine
Enigma was the name given to the world's first commercially successful machine for encryption and decryption. It was invented in 1918 by Arthur Scherbius of the small, inventive engineering firm Scherbius & Ritter. By the late twenties, Scherbius had managed to get a contract with the German armed forces and eventually, some 30,000 of the machines were built and used for all kinds of crypto traffic by the German Navy, Army and Air Force. But it's not for this that the Enigma is best remembered, but for the fact that, while the security it offered was great for the time - indeed it was thought unbreakable by the Axis powers and most other people too until about 1975 - despite this security, the Enigma cypher was broken very early by the Polish intelligence services and most famously, by a "dream-team" of code-breakers based at Bletchley Park in England, for most of the duration of WW II.