An encrypted bit file cannot be created for XC4VSX35 with the 7.1 version of the design tools. The following error occurs:
"7.1i BitGen - "FATAL_ERROR:Bitstream:xv4bsbitfile.c:2565:188.8.131.52 - Number of bytes in bitstream (1707240) should be multiple of 16 for AES encryption Process will terminate. To resolve this error, please consult the Answers Database and other online resources at http://support.xilinx.com/. If you need further assistance, please open a Webcase by clicking on the "WebCase" link at http://support.xilinx.com/ Error: bitgen failed." "
This issue will be fixed in ISE 8.1i SP1, scheduled to be released early 2006. If an encrypted bit file needs to be created, contact Xilinx Technical Support.