Cryptography with Paint

A friend once asked me how cryptography works. That is, how can 2 parties communicate something secretly with a 3rd party always listening? Well here's an awesome primer on how cryptography works in the modern world that answers this very question.


Some notes while researching computational complexity theory(one way functions and the like):

• There's also a 'trapdoor one-way function' or just trapdoor function:
• 
  1. If a function |code: x(1, 2, 3)| is passing elements like the figure above, it's called an injective surjective function. It's a bijection, which means the pairing of elements is exact. There are no unpaired elements.
• 
  If the same function |code: x(1, 2, 3)| performs the change shown above it's called an injective non-surjective function. This is obviously not a bijection.
• 
  And this would be considered a non-injective surjective function. It's a surjection, which means some elements will be turned into the same element.

Just some handy terminology for reference. It's also nice to match the terminology with a process we can understand through a visual representation. So there's some hip coder lingo.

nice video describing the above from khan academy here