gzDecryptor, A Small Firmware Tool

This is a small tool to simplify some firmware related jobs. Normally, you will take the following steps when you’ve got a new firmware:

1. Decompress firmware
2. Decrypt ramdisk
3. Extract rootfs decryption key
4. Decrypt rootfs
5. Extract important files

If you are on Mac OS X, you are lucky because you can easily find all the needed tools for the above jobs, and you can write an easy wrapper script to automate these jobs, but on Windows, there seems no such a tool yet, that’s why I write this small tool, gzDecryptor.

Works on 2.0 5A274d and under.



To use gzDecryptor, simply choose your firmware file, and click Decrypt button, it will create a folder (same name as your firmware, but without extension) and extract firmware contents into the folder, then a decrypted folder will be created to hold all the decrypted files.

gzDecryptor uses openssl to decrypt ramdisk, uses vfdecrypt to decrypt rootfs, uses dmg2img (code from soft-upgrade) to extract the partition from decrypted rootfs, then it tries to extract baseband files and secpack.

After the decryption, you get the following files:

ramdisk.dmg (mountable ramdisk image)
rootfs.dmg (mountable rootfs image)
key.txt (contains rootfs decryption key)
secpack
ICE*.fls, ICE*.eep (baseband firmware)
lockdownd

The following is the snapshot of the decrypted files for firmware 2.0 Build 5A258f:



More info, via George Zhu’s Blog

[Red_5]

Does it work on the 6Gs?

(praying earnestly)

[Bolt]

yeah what does this decrypt? anything aside from ipod touch?

[bounci.rabbit.123]

Well it looks like it can decrypt iPhone firmwares from the screenshot...and i guess itouches too. He wouldn't have written this program if the encryption key wasn't already known. I'd assume that this will not work on classics and new nanos.

[Kedzi]

iPod Touch (2.0 and under)...
Cool

[zim]

THIS IS SWEET *we dont spam here zim*

[xBrandonx]

Spammer. Open up a thread in the Shop District.

This is just too Jailbrake the Touch/Phone then?

[Twinkie]

Brandon, rather than just calling him a spammer, why didn't you do your job and remove it?

I need to have a word with you btw.

[dajavax]

Originally Posted by Fatty Mc.FatFat

I need to have a word with you btw.

that sounds like trouble =S...

anyways... cool tool... might actually be useful... maybe even more with the pwnage tool... you can edit firmware and restore your ipod with it =D

[Legendary]

Nice Find Matt. I doubt this can crack 6g firmwares... Someone would have done it by now if it could