This is a cross platform dmg decryption tool. Maintained by quasarboi, but credit goes to its original owner.

To build on Linux, run "make linux";
To build on Mac, run "make mac";
To install, run "sudo make install";
To run, run "vfdecrypt";
To clean, run "make clean";
To uninstall, run "sudo make uninstall".

Usage: vfdecrypt -i in-file [-p password] [-k key] -o out-file

NOTICE: The -i and -o flags are extremely important, as without them, the program will never terminate unless forced to.
NOTICE: ONLY the -k -i and -o flags have been tested.

Depends:
libssl0.9.8

Example: 
Decrypting iOS 4 in your home directory.
Once the program is compiled and installed, run:

"vfdecrypt -i name_of_root_filesystem.dmg -k ec6eb0268c4e9f8ab9d003f601e8f4b36f4fc4311c61e5ebed07ce718424ffee7e7d924d -o decrypted.dmg"