The paper is titled Oracle Authentication and it includes a detailed discussion of the Oracle password algortithm including an implementation in python. I am not sure how fast that would be (haven't tested it against tools such as woraauthbf which is written in C and includes the source code and is extremely fast. A new version on woraauthbf is due out soon with some new features, I have been testing it for Laszlo, watch this space for an announcement of when its available.
Back to the paper; this paper explains the algorithm and also delves into the TNS packets that are sent to the server as part of the O3Logon process. The paper concludes with some details of attacks against the protocol including version divulgeing and also user enumeration.
I have talked here about the 11g password algorithm, including a simple PL/SQL script that implements the 11g password algorithm and also a discussion of weaknesses in the 11g password algorithm. There are plenty more discussions here around the Oracle password algorithm, use a simple query on google for site:www.petefinnigan.com Oracle password algorithm to locate some of them.