How to generate a single DES bitstream for Virtex-II devices?
Triple DES has yet to be cracked, and Xilinx strongly recommends this strategy for designs, reference (Xilinx Answer 13823).
If a single DES bitstream needs to be generated for some reason, make all three keys identical and you will have a single DES. For example, the BitGen option can be enabled in ISE by following these steps:
1. In Project Navigator, in the Processes for Source pane, right-click Generate Programming File.
2. Select Properties.
3. In the Encryption Options tab of the Process Properties window, set the options to:
Encrypt Bitstream: checked
Key 0 (Hex String): 123456789abcde
Key 1 (Hex String): 123456789abcde
Key 2 (Hex String): 123456789abcde
Key 3 (Hex String): edcba987654321
Key 4 (Hex String): edcba987654321
Key 5 (Hex String): edcba987654321
Input Encryption Key File:
Location of Key 0 in Sequence: First (F)
Location of Key 1 in Sequence: Middle (M)
Location of Key 2 in Sequence: Last (L)
Location of Key 3 in Sequence: First (F)
Location of Key 4 in Sequence: Middle (M)
Location of Key 5 in Sequence: Last (L)
Starting Key: 0
Starting CBC Value (Hex):
4. Click OK.
The command line equivalent is as follows:
bitgen myinput.ncd -g security:level1 -g Encrypt:Yes -g Key0:0x123456789abcde -g Key1:0x123456789abcde -g Key2:0x123456789abcde -g Key3:0x123456789abcde -g Key4:0xedcba987654321 -g Key5:0xedcba987654321 -g Keyseq0:F -g Keyseq1:M -g Keyseq2:L -g Keyseq3:F -g Keyseq4:M -g Keyseq5:L -g StartKey:0