Always remember the following rules:

• Rule number one: Do not attempt to create your own hash or encryption functions. Simply don't. Use tools and functions that are there already. It is incredibly tough to come up with a good, solid, robust algorithm to do hashing or encryption, so it's best to leave it to professional cryptographers.
• Rule number two: Follow rule number one.

Those are the only two rules you need. Apart from them, it is very useful to understand cryptography, so you need to try and learn as much as you can about this subject. There is plenty of information on the web, but for your convenience, I'll put some useful references at the end of this chapter.

Now, let's dig into the first of the standard library modules I want to show you: hashlib.