dd /dev/zero is referred to as Forensic Wipe and is typically done before forensically imaging data from one device to another in order to mitigate cross contamination. This includes new devices freshly removed from their packaging due to manufacturer files and so forth.
EXECUTE FORENSIC WIPE:
Download "dd for Windows" and open Windows Command-line ("cmd.exe").
Type: "cd /D [directory]" to the "dd" folder.
Type: "dd --list" to show list of Volumes, Disks, and Partitions. Locate your device.
Type: "dd if=/dev/zero of=\\?\Device\Harddisk1\Partition0 --progress"
Choose between "/dev/zero" and "/dev/random" as the write operation. Ensure you select your device based on step 3.
VERIFY ZERO WRITE OPERATION:
Wait for the zero or random write process to complete and then run hexdump to display hexadecimal value, which should read all zeros for "/dev/zero" process. Choose one of the following:
Type: "dd if=\\?\Device\Harddisk1\Partition0 | hexdump -C"
Type: "hexdump.exe -C \\.\d:" where [\\.\d:] is [unformatted directory]
The result of Zero Write using "dd if=\?\Device\Harddisk1\Partition0 | hexdump -C" and will continue parsing zeros (null data) until the end of the drive. The drive used in the image was NOT formatted after executing the Zero Write procedure. The following image depicts what would be considered a Zero Write success:
The hexadecimal printout result after ONLY formatting the drive. This shows any alteration to the drive contents will trigger a printout instead of running through the entire drive showing all zeros (null data). The following image depicts what would be considered a Zero Write fail:
The drive must be in an unreadable state (RAW - format drive before use) otherwise "Error native opening file...operation completed successfully" or "Error writing file...Access is denied" will result without any action taken using the Windows based "dd" tool.
The easiest method for placing the drive into RAW state is to execute the "/dev/zero" process explained above, it will immediately fail, then remove and reinsert the drive. The "format before use prompt..." will appear, click cancel, and then repeat the same "/dev/zero" process to either write zeros (null data) or pseudo-random data to the drive.