Encryption program finally finished!

I recently (today, in fact) finished working out all of the bugs in my Python encryption/decryption script. I'm actually quite proud of it, which is why I'm making this entry, obviously.

It works by taking the ASCII value of each character (a number that represents each letter, number, or symbol) in a line of text or .txt file and shifting them a set number of values. I know, that doesn't seem very fancy, but it has a second part too: it takes a key, say, four, and then makes length / key strings of characters in order to rearrange them. The end result can look something like this:

I'm going to be encrypted!

zA8CX:!G@!88!GA7:B6 B!E <5L

So, yeah. I like it. And it actually works on multi-line text files, which I had to spend over an hour debugging because I wasn't used to file selection and different semantics of read/write operations in Python. Also I had an if statement that should've been indented one more block and caused line breaks to turn into the letter h during decryption.