DO NOT GUESS! There are different locations in the address of the hex code for different Hitachi firmwares, in JF this is what was seen on my firmware.
CODE
Loading Hitachi Dump file
Inquiry string found
Identify string found
DVD key found @ 0x4C30 key is CB267A9F353CAF5160AF5ED8D5358
Firmware is Hitachi OSIG: HL-DT-STDVD-ROM GDR3120L0078
Firmware type is: iXtreme :78:V1.4-12x
so as you can see I had the 1.4 firmware on it, and my key was located at 0x4C30 in the hex code of the firmware. So I flashed my 78 with iXtreme ix151-78-4c30, as that would then flash my key correctly.
You have a 78 version, so depending upon where your key is located, it may be one of the firmware's, the types for 78's are...
ix151-78-4b00
ix151-78-4C30
ix151-78-4d20
ix151-78-4e10
So depending on where you key is located in your firmware will depend upon which version you will flash. As I said you need to find out which version you need to use.