Abstract: The adoption of three new “post-quantum” cryptographic algorithms by the National Institute of Standards and Technology has raised broad concern about the impact of transition to the new systems. This is not the first time we have needed to make major changes in cryptography; it is the fourth such change in a little over a century. We will look at each of these changes and consider the implication: when and what will be the next change?

Bio: Whitfield Diffie is best known for his discovery of the concept of public-key cryptography, which he developed jointly with Martin Hellman at Stanford University in the mid-1970s. The two shared the ACM Turing Award in 2015 for work that “made cryptography scalable to the Internet and revolutionized the landscape of security.” Retired from positions as head of security for the Canadian telephone system and Sun Microsystems, Diffie is now an Honorary Fellow of Gonville and Caius College in Cambridge. He is a member of the National Academy of Engineering, the Royal Society, and NSA’s Cryptologic Hall of Honor.