title: Convert a string of 0-F into a byte array in Ruby
body: <p>I am attempting to decrypt a number encrypted by another program that uses the BouncyCastle library for Java.</p>
  
  <p>In Java, I can set the key like this:  <code>key = Hex.decode("5F3B603AFCE22359");</code></p>
  
  <p>I am trying to figure out how to represent that same step in Ruby.</p>