XFAuth takes care of user authentication
This class implements the stream cipher RC4 - see http://en.wikipedia.org/wiki/RC4 The length of s-box is full 256-bit.
This class implements the block cipher Blowfish - see http://en.wikipedia.org/wiki/Blowfish_(cipher)
XFImage abstracts php image function to draw bitmap and vector based
XFLog provides a general-purpose logging facility
XFMail is currently a simple abstraction for mail()
XFParser takes care of text processing, tag management and some more