Encrypt a custom firmware

Hi, all!
I'm trying to build a custom firmware for my iPhone 2G.
I successfull decrypted a 3.1.3 firmware with vdecrypt and key, so I can mod filesystem as I want (converting .dmg to Writing/reading UDRW)

Anyway i would like to make the final ipsw, but i have some problems:
or I get error 14 during flashing (but the firmware seems not corrupted) or iTunes says it that teh firmware is corrupted
[also tried to make no modification, just to try.. same result]

I found this:

Step 1:use vdecript OK!
Step 2: hdiutil convert -format UDRW -o udrw.dmg 018-6482-014.dmg OK! [convert to reading/writing]
Step 3: hdiutil mount udrw.dmg OK!
After the third step you are able to make changes to the mounted filesystem OK!

Step 4: diskutil rename /Volumes/BigBear5A347.M68OS LittleBear4A102.UserBundle
(it is old, 3.1.3 is called SunNorthstarTwo7E18.iPhoneOS)
CAN YOU EXPLAIN THIS? what is the meaning of this "rename"?

Step 5: hdiutil eject /Volumes/LittleBear4A102.UserBundle


Step 6: hdiutil convert -format UDZO udrw.dmg -o udzo.dmg OK! [covert to compressed]
Step 7: asr -imagescan udzo.dmg OK!
Step 8: mv udzo.dmg 018-6482-014.dmg OK!

Now all you need to do, is to replace the 018-6482-014.dmg in the custom-firmware created with Pwnage OK!

 

workprogress:
http://iphone2g.netsons.org/