Mathematical Cryptosystems (1 of 2: Symmetric Cryptography)

[westronic]

4:30 "You would use its inverse, which very unimaginably is named..." "Sine inverse" Had me laughing out loud! I'm going to have to use that when I teach.

[mulimotola]

At the end of the video you mention that symmetric keys aren't used today, but that's wrong. Our computers start with asymmetric encryption, but after that's established, then a symmetric key is transmitted, because symmetric encryption is faster than asymmetric. So we start with asymmetric, but then switch to symmetric. That's how web browsers communicate over SSL.

[nerotyc]

When you talk about inverse functions you assume that it exists (true for bijective functions). But there are surjective functions where the inverse relation for one image element returns a set of size greater one so there's no such thing as an inverse function.