Recent history: technology challenges
With the launch of communications satellites starting in the 1960s, many communications migrated away from the traditional media of High Frequency (Short Wave) Morse and teleprinter, although neither seems likely to disappear altogether. From the 1970s onwards, these changes enabled a dramatic reduction in the numbers of intercept stations owned or directed by GCHQ.
GCHQ made a major breakthrough in the field of secure communications in 1973 when Cliff Cocks, James Ellis and Malcolm Williamson developed what is now known as public key cryptography, several years before it was independently discovered by Diffie and Hellman in the US.
The most significant technology change of the post-war period has been the development of the Internet from the early 1990s to the present day. GCHQ’s targets generally use the same technologies as the wider population. Hence the volume and diversity of the modern communications environment presents GCHQ with an even greater challenge than the old Soviet Bloc, one that will continue to test our ingenuity to its limits.