My paper can be of some value in this respect : Magdy Saeb, Hala Farouk, "An FPGA implementation of a special purpose processor for steganography", IEEE conference on Field Programmable Technology,FPT2003 conference proceedings, University of Tokyo, Japan, 2003.
Also please check my home page for other related work: www.madysaeb.net
There is also a book chapter that may help answer your question: