Heath Robinson (codebreaking machine)

Heath Robinson was a machine used by British codebreakers at the Government Code and Cypher School (GC&CS) at Bletchley Park during World War II in cryptanalysis of the Lorenz cipher.

It was mainly an electro-mechanical machine, containing no more than a couple of dozen valves (vacuum tubes),[2] and was the predecessor to the electronic Colossus computer.

It was dubbed "Heath Robinson" by the Wrens who operated it, after cartoonist William Heath Robinson, who drew immensely complicated mechanical devices for simple tasks, similar to (and somewhat predating) Rube Goldberg in the U.S.[3] The functional specification of the machine was produced by Max Newman.

[5] Dr C. E. Wynn-Williams from the Telecommunications Research Establishment at Malvern produced the high-speed electronic valve and relay counters.

[5] Construction started in January 1943,[6] the prototype machine was delivered to Bletchley Park in June and was first used to help read current encrypted traffic soon afterwards.

[7] As the Robinson was a bit slow and unreliable, it was later replaced by the Colossus computer for many purposes, including the methods used against the twelve-rotor Lorenz SZ42 on-line teleprinter cipher machine (code named Tunny, for tunafish).

[8][9] The basis of the method that the Heath Robinson machine implemented was Bill Tutte's "1+2 technique".

component of the key to be removed and the resulting modified message attacked by manual methods in the Testery.

This was changed to drive by friction pulleys with the sprocket wheels maintaining the synchrony when it was found that this caused less damage to the tapes.

[13] This was designed by Tommy Flowers of the Post Office Research Station at Dollis Hill in North London.

Wynn-Williams had obtained his PhD at Cambridge University for his work at the Cavendish Laboratory with Sir Ernest Rutherford.

[15] In 1926 he had constructed an amplifier using thermionic valves (vacuum tubes) for the very small electrical currents arising from detectors in their nuclear disintegration experiments.

Rutherford had got him to devote his attention to the construction of a reliable valve amplifier and methods of registering and counting these particles.

The Wren operators initially had to write down these numbers before the next count that exceeded the threshold was displayed – which was "a fruitful source of error",[16] so a printer was soon introduced.

[18] However, Tommy Flowers realised that he could produce a machine that generated the key stream electronically so that the main problem of keeping two tapes synchronised with each other would be eliminated.