Captain Raymond "Jerry" Roberts, who died yesterday following a short illness, was part of a team at Bletchley Park, in Buckinghamshire, which helped to crack the German Tunny system used by Hitler, Mussolini and other high ranking generals during the Second World War, a Bletchley Park spokeswoman said.
Capt Roberts joined Bletchley Park at a cryptographer and linguist in 1941 and was one of four founder members of the Testery, an elite unit named after the man leading it, Ralph Tester, which cracked the Tunny code making it possible to read Hitler's messages during the war.
The team managed to reverse engineer the Tunny, which had 12 encryption wheels to the Enigma machine's three, described by Bletchley Park as "an incredible feat of dedication".
The spokeswoman said: "Jerry came to Bletchley Park straight from university but they were all in unchartered territory. It was new ground for everybody."
The intelligence gathered at Bletchley Park is credited with providing strategic information that was passing between the top level commanders and is believed to have shortened the war by two years and helped to save millions of lives.
The spokeswoman said: "In the last six years of his life he campaigned absolutely tirelessly for awareness and the achievements made at Bletchley Park.
"During the war, people in one room did not know what people were doing in the next room, never mind another department. It's still a jigsaw puzzle even now."
Describing Capt Roberts as "lovely" and "absolutely charming", she said: "He was passionate about what he and his colleagues achieved.
"He did not want to blow his own trumpet but to have the work of his colleagues recognised."
Capt Roberts worked at Bletchley Park until 1945 before moving to the War Crimes Investigation Unit followed by a 50-year career in marketing and research.