Information Security--Before, During, and After Public-Key Cryptography, lecture by Whitfield Diffie
From abstract: "In the 1970s, the world of information security was transformed by public-key cryptography, the radical revision of cryptographic thinking that allowed people with no prior contact to communicate securely. "Public key" solved security problems born of the revolution in information technology that characterized the 20th century and made Internet commerce possible. Security problems rarely stay solved, however. Continuing growth in computing, networking, and wireless--including applications made possible by improvements in securityùhave given rise to new security problems. Where is this going? Diffie, a key figure in the discovery public-key cryptography, will trace the growth of information security through the 20th Century and into the 21st."