Run:
openssl enc -d -in ramdisk.dmg -out de.dmg -aes-128-cbc -K 188458A6D15034DFE386F23B61D43774 -iv 0

Ignore the error. Then there will be some garbage, signatures and certificates, at the end of the file. Remove it and mount your ramdisk.

Why would this key be published without any explanation of what it is? Apple knows what it is, not telling us how to use it doesn’t serve a purpose for anyone. I don’t know exactly what this key is or where it came from. But I do know it decrypts ramdisks

Nice job to Zibri, the dev team, and whoever owns Austin Heap for finding this key, I’d love to see the hack used. Sadly this will not help us unlock BL 4.6 phones, or sign our own SDK apps; sign anything for that matter. But hopefully this key is deeply embedded in the iPhone, and decrypting all future ramdisks will be a piece of cake.

http://iphonejtag.blogspot.com/2008/01/iphone-secret-key.html

“I wonder how rumors run quickly and I am very disappointed
by Erica Sadun of TUAW for telling people this was
a key related to SDK or the “Application Key”.
Well.. i never said it. And, frankly, it’s NOT
I posted this only because I hate disinformation.”

Eller se det her: http://zibree.blogspot.com/