How the tech vanguard turned public-key cryptography into one of the most potent political ideas of the 21st century.
Cryptography is the art of secret communication. Diplomats and military commanders began using secret keys to encrypt their missives thousands of years ago, long before the invention of computers or even the telegraph. To establish secret communication, participants must first have the secret key. Thus arises the problem of key distribution— how to share a secret key with all participants of a secure conversation before the conversation starts. For centuries, key distribution gave large organizations a big advantage. The more resourceful a state’s military and intelligence establishment, the more easily it could manage the logistics of key distribution.
Perhaps the single most significant invention in the history of cryptography came to be in 1973: public-key encryption, or “nonsecret” encryption, as its inventors called it. It is probably the only mathematical algorithm that spurned its own political philosophy. Ironically, “nonsecret” encryption was first discovered in secret at the British eavesdropping agency Government Communications Headquarters (GCHQ). And it was kept secret for many years.