Hello again. This group of lessons explores
the concept of randomness. It discusses how and where
to use it in your programs. We'll introduce the concept
of pseudo-randomness, and how it affects your programs. Last, we will touch briefly on the fundamentals
of cryptography, and give some cryptography
examples. Let's start. Now, the goals of
this section for randomness are
basically to show you how using random numbers works, and some of the pitfalls
that may occur. One of the biggest pitfalls is the notion of
pseudo-randomness, where you get
something that looks random but is
actually predictable. We'll talk about this in a little bit
more detail, in a bit. We're also going to
look a little bit at what at randomness actually is, so we can distinguish between
random and pseudo-random. Then if you go on
to the slide about the section on cryptography, we're going to look at
a couple of things here. We're not going to talk about
cryptography in general. Basically, we're
going to assume you know little bit about that. But what we are going to do is talk about how crypto is used, and also when to use it
and how not to use it, and also what not to do. So we'll talk about basic use when you're
programming and how to do it. The basic rule of
cryptography to take a step forward is simple, don't write it yourself. Unless you absolutely
have to write it, don't. Use libraries that are trusted and that had been written
by professionals, or by people who really
know their cryptography.