[pycrypto] Digest and MAC parameters with PBKDF2()

[Hutton, William J]

The PBKDF2 documentation at http://www.dlitz.net/software/python-pbkdf2/ is
a little sparse, so I'm hoping someone on the list can answer a few
questions for me.

1. How can I use hashlib.ripemd160 as the hash function with PBKDF2()

2. What is the difference between the digestmodule parameter and the
macmodule parameter?

I thought deriving a key using PBKDF2 required a password, salt, iteration
count, and hash function.

Thanks in advance for any light you can shed on this topic.