/root encryption is still broken

[Bruno Wolff III <bruno wolff to>]

I tried out today's boot.iso and things got further. It appears that the
install was successful using encrypted raid 1 partitions. (This used
to fail.) But when I tried to boot the system, I wasn't asked for
a password. During the boot process /dev/root couldn't be mounted. Things
continued for a short while and then hung up after some usb devices
were detected.
For a problem like this, what component should be used?