Development of Creative Commons licenses

[Matt Scheuerman <mordecaidesign AT gmail.com>]

Greetings,

I am currently developing some graphics that I want to release under
certain conditions:

* users can employ the graphics for any medium and can use the
graphics for commercial and non-commercial work.

*Credit to the original author in any form is not mandatory but is
highly appreciated.

*The files may be changed/updated/manipulated/redistributed as long as
they are accompanied by a text file giving original credit to the
author.

So is there a license I can use already written or should I manipulate
and write my own?