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The technological secrets behind spying over a century - from World War Two code breaking tools to Cold War secrets - are to go on show.
Top Secret: From Ciphers to Cyber Security, at London's Science Museum, will feature more than 100 objects from GCHQ - the government's listening post.
Jeremy Fleming, the director of GCHQ, said the organisation's work had "saved countless lives... shortened wars, given Britain an edge, and solved or harnessed some of the world's hardest technology challenges".
People will be able to see historical technology, hand-written documents and declassified files from the Cheltenham-based spy agency.
The exhibition will run from 10 July to 23 February 2020.