I took his Introduction to Cryptography class when he was a visiting professor at Columbia. Absolute master of an old-school chalkboard lecturer. They don't make them like that any more.

Hugely engaging, the margins of my notebook had many of his quips… there was an archive online somewhere.

e.g., x minus x is zero, even for Euler, so therefore…

Found on Archive, https://web.archive.org/web/20210509160248/http://www.eecs.h...