Information / Communication & Networks

Public-Key Cryptography

Two keys instead of one: strangers can communicate encrypted and verify signatures without any prior exchange, the basis of HTTPS.

Whitfield Diffie and Martin Hellman published key exchange over open lines in 1976; RSA by Rivest, Shamir and Adleman followed in 1977, whose security rests on the difficulty of prime factorization. British intelligence staff (Ellis, Cocks, Williamson) had discovered it in the early 1970s but could only reveal it in 1997. Today the method (now also with elliptic curves) secures online banking, certificates and software updates.