How to use Encrypted Disk images for KVM based guests?

Issue

• I'm currently using libvirt-0.10.2-18 on my RHEL machine and I'd like to:

1. Convert the disk-image of the guests from RAW to QCOW2
2. Encrypt these disk images after conversion.

• I used the following command to create the encrypted image (based on documentation I found online):

# qemu-img create -o encryption -f qcow2 CryptoTest.img 4G

• But, when I try to run it via virt-manager I get:

"Unable to execute QEMU command 'cont': Device 'drive-virtio-disk0' is encrypted"

• So, the created image seems to be encrypted, but I am not able to start the guest using this disk-image.
• I did not find anything on - how to set a password or key file for the encrypted image file and how to get it running.