Before computers, we transferred long text documents to each other through the mail. You would write your letter and then place it in an envelope. Then you'd steal and stamp the envelope before placing it in the mail.
Consider for a moment why you sealed the letter. Is it because you want to keep the contents of the letter top secret? Or maybe you just want the receiver to know that no one has read the letter before them? Maybe it's just the extra security of knowing that the letter will not be fall out before reaching its destination.
So why don't we do the same thing with email? The reason we encrypt email was eloquently described to me with the same envelope analogy. An email is more like a postcard. Most people wouldn't read it, because hey, it's not to them. But it'd be very easy for someone to turn over the letter and read what you wrote. Its also probably not the best way to protect sensitive information.
Cryptography started with hand written codes you may or may not have heard of. They've become bigger with the rise of spy movies and most are easy to break with the right knowledge. For example, you may have played with letter substitution codes as a kid in school. Or you may have seen the book code on TV (where you get 3 numbers, the page, the line, and the word, and they all correspond to words in a particular book.) However, the encryption on emails and other files is a little more sophisticated.
Next post we'll talk about some of the keywords you should know and how to do a basic file encryption.
Have you ever used encryption for work?