This is a repo for stuff related to Cryptography I on Coursera. No full solutions here; I will only post things that I feel don't violate the honor code (and in fact not even anything that I wouldn't freely post on the course forums)

HexMessage

This is a class to make it easier to convert between strings and hex representation of strings and things that can be xor'ed together. Right now it assumes all strings are UTF-8 because this is a quick thing I banged out in a hurry; I may fix it later.

I wrote it for Python 3, and Unicode is one place where Python isn't backward-compatible at all. If you're using Python 2 you might find inspiration here but you'd also have to almost rewrite the thing. If you do, please give me a pull request (as hexmessage_2.py) and I'll add it.

Usage

The constructor can take either of:

• A bare UTF-8 string. (HexMessage("hello world"))
• A hex-encoded bytes object (HexMessage(b'6c73d5240a948c86981bc294814d'))

The ^ operator is overloaded (and really, the point of all this). You can xor with any of:

• A UTF-8 string (a ^ "sup bro")
• A hex-encoded bytes object (a ^ b'7375702062726f')
• Another HexMessage object (a ^ b)

In each case it returns a new HexMessage.

__str__ and __repr__ are overloaded differently to make it easy to look at the hex representation or the string representation as needed (a in the REPL will show the hex, while print(a) will show the string)