When installing from something involving an ISO image, d-i will load the wrong loop module and later on setting up loop-aes will fail.
After generating enough randomness, you will receive the message “An error has occured while configuring encrypted volumes”, and the syslog shows
partman-crypto: ioctl: LOOP_SET_STATUS: Invalid argument, requested cipher or key length (256 bits) not supported by kernel.
To fix this problem, first proceed to the partitioner and select encryption with loop-aes. That will make d-i unpack the necessary files to
Now switch to a console and
modprobe -v -r loop (this is a rmmod replacement.)
You will probably need to umount the cd image first:
(Now try again:
modprobe -v -r loop)
(this will load the right
loop module for use with loop-AES!)
You might want to remount your cdrom:
mount /hd-media/*.iso /cdrom -o loop
(Alternatively, you can Esc out a few times in d-i and select the autodetection from the main menu again.)
Now you should succeed in setting up loop-aes.
(This problem should be fixed in one of the next debian-installer versions.)