The building of SIGSALY (1943) : pioneer digital telephone system
Another secret wartime computer whose existence was finally revealed many years later was SIGSALY - the secret 'scrambling' system devised to protect the security of high level Allied telephone traffic.
SIGSALY - originally codenamed Project X - was also known as 'Green Hornet'. It was the first unbreakable speech coding system, using digital cryptography techniques, with one time digital keys being supplied by synchronised gramophone discs.
SIGSALY was built in the USA, though using pulse code modulation (PCM) digital encoding techniques invented in 1937 by the English engineer Alec Reeves.
The first priority was to protect the hotline between the Cabinet War Room bunker under Downing Street and the White House in Washington D.C. The 50-ton London terminal was shipped over in 1943 and housed in the basement of the Selfridges annexe in Oxford Street, under tight guard.
Another secret wartime computer whose existence was finally revealed many years later was SIGSALY - the secret 'scrambling' system devised to protect the security of high level Allied telephone traffic.
SIGSALY - originally codenamed Project X - was also known as 'Green Hornet'. It was the first unbreakable speech coding system, using digital cryptography techniques, with one time digital keys being supplied by synchronised gramophone discs.
SIGSALY was built in the USA, though using pulse code modulation (PCM) digital encoding techniques invented in 1937 by the English engineer Alec Reeves.
The first priority was to protect the hotline between the Cabinet War Room bunker under Downing Street and the White House in Washington D.C. The 50-ton London terminal was shipped over in 1943 and housed in the basement of the Selfridges annexe in Oxford Street, under tight guard.
