Intro to Public-Key Crypto 🔑

An extremely short intro to cryptography, and why *public-key* cryptography changed everything.
(Next video will give an example demo'ing why public-key crypto is even possible.)

The page demo'ing the book-cipher is:
https://www.dcode.fr/book-cipher

Contents:
- 00m15s -- why public-key encryption is important (& the web is just packets)
- 01m45s -- Caesar cipher & permutation ciphers
- 02m38s -- remember that *pre*-arranged keys are essential to traditional encryption
- 03m25s -- book cipher
- 06m03s -- one-time pad
- 07m53s -- but how to pre-arrange a key, in spite of continual eavesdroppers
- 09m20s -- notation: encrypt, decrypt as functions `e`, `d`
-10m40s -- how a public-key system would be used (incl. some early-history)