In AES encryption and decryption algorithm after writing the code,i have been getting the following synthesis report(files attached)....is there any perticular method to reduce the slice utilization or i have to do modification in the code itself.
There's a couple of optimization buttons you can play with, but don't hold your breath. (*) If you want any significant reductions in resource utilization then that generally means you'll have to rethink some parts of the design.
(*) No don't even ask. It's not worth our collective time. The most efficient use of time really is spent on the design, not me explaining to you what the various buttons do. If you really are curious, I suggest you read the XST manual. Google for "xilinx xst user guide". For example for spartan-6 + virtex-6: https://www.xilinx.com/support/documentation/sw_manuals/xilinx14_5/xst_v6s6.pdf