Bug#641264: debian-installer: cannot install to already encrypted partitions

[Johan Vervloet <johan.vervloet@gmail.com>]

Hello,

Today I downloaded an installation-CD for debian wheezy, and I ran
into the same problem.  You gave a great tip with anna-install, but I
ran into other troubles.  When I try to decrypt my encrypted
partition, I get the message

device-mapper: reload ioctl failed: Invalid argument
Failed to setup dm-crypt key mapping for device /dev/sda6.
Check that kernel supports aes-xts-plain64 cipher (check syslog for more info).
Failed to read from key storage.

I tried to modprobe xts, but that didn't fix it.  Do I need another
module, or is this cipher just not supported by the wheezy-installer?

Thanks,
Johan