I have been trying to get Raspbian Jessie, installed from the image to boot with an encrypted root partition.
I was successful in following the guide here.
When I boot the Pi, it drops to an initramfs prompt, then I unlock the partition with
# cryptsetup luksOpen /dev/mmcblk0p2 sdcard # exit
and it boots into Debian. Great!
However, there are some issues. When I try to update the initramfs file with:
# sudo mkinitramfs -o /boot/initramfs.gz
in Debian, the Pi doesn't successfully reboot to the initramfs prompt. It just hangs with a blinking cursor after showing the pixel logo. When I restore to my backed-up boot image, I get the initramfs prompt again and can boot from the encrypted root.
The second issue is that I did not properly configure dropbear; it appears to be configured to use DHCP. This means that when I log in it gets a random IP address. I need to update the configuration to a fixed IP address so that I can log into the Pi headless after a reboot, but without the ability to update the initramfs I don't know how to fix this.
Given that I can't even get an initramfs prompt after the update, I'm really not sure how to even start solving this problem, so any hints would be great. I'll provide whatever information that will be helpful to solving this issue.