Diffie & Hellman are truly the heroes ahead of the time. 43 years ago, 1976, at the DES review, they had a entertaining debate with NSA employees.

Martin Hellman said,

* 56/64-bit symmetric crypto is insecure, and chosen to benefit NSA.

* 100-200 bits of security should be secure, but is still vulnerable to attacks by quantum computers.

(Glover & Shor's algo were not discovered until the late 90s! We now know 128-bit is pre-quantum secure, 256-bit is post-quantum secure, Martin was completely correct.)