It's possible to pack your own firmware images without any keys - the caveat is that flashing them will put your phone into open mode no matter what starting with the PR1.2 bootloader version. The procedure is to: Unpack FIASCO image using flasher 3.5 Unpack sparse image (rootfs.jffs2) using unlzo.py Mount rootfs image as an ext4 loopback device Do what you'd like Unmount rootfs Repack sparse image using sparsify.py Build FIASCO image from sparse image and layout file using fiasco-gen Flash FIASCO image to device using flasher 3.12.1 It isn't very easy to do, and most of those steps have to be done from a Linux system. Also, realistically, it isn't all that useful - though I released sparsify hoping that someone would do it anyway. If you really want to pack a custom image I'd help out with more info. Edit: On second thought, one potential use would be for quick deployment of NITDroid, but IIRC e-yes wasn't too interested in this.