Security, Commerce, and Computing's Future

For most of the twentieth century, secure communication relied on symmetric-key cryptography, in which both sender and receiver shared the same secret key, a method that works well for a single conversation but scales poorly across the many independent parties that would eventually need to communicate securely over open networks like the internet. This changed in 1976, when Whitfield Diffie and Martin Hellman, building on ideas from Ralph Merkle, published "New Directions in Cryptography," introducing public-key cryptography, a system in which each party holds a mathematically linked pair of keys, one public and one kept private, allowing secure communication and digital signatures to be established between strangers without ever having exchanged a secret key in advance. In 1977, Ron Rivest, Adi Shamir, and Leonard Adleman at MIT developed a practical implementation of this idea, the RSA algorithm, based on the mathematical difficulty of factoring the product of two large prime numbers, which became foundational to internet security protocols still in wide use today, including the encryption behind the padlock icon in a web browser's address bar. Notably, British intelligence mathematicians James Ellis, Clifford Cocks, and Malcolm Williamson had developed equivalent concepts several years earlier, around 1970 to 1973, at the UK's Government Communications Headquarters, but this work remained classified and was not publicly acknowledged until 1997, well after Diffie, Hellman, Rivest, Shamir, and Adleman had independently and publicly developed and popularized the same fundamental ideas.