David Ashby on SHA256

http://paperswelove.org/2017/video/david-ashby-shamwow/

While most of us use hash functions on a daily basis, few people can say that they truly understand what’s actually going on when they call SHA2("hello world"). Even fewer can say they’ve bothered to implement the function themselves, considering every introduction to cryptography starts off with a big warning saying to never, ever implement cryptographic primitives and just use vetted libraries due to the security implications.