cryptsetup-luks is a utility that is used for managing encrypted
partitions and volumes. It was originally based on cryptsetup, and
adds support for LUKS (Linux Unified Key Setup). LUKS is a standard
on-disk format that stores all necessary setup information in the 
partition header.

To compile this package, the device-mapper package is required. This
package is available from the extra/lvm2 directory of your Slackware
Linux 11.0 distribution medium. Actually, cryptsetup-luks will compile
without having this package installed, but it won't be able to do
anything useful, because it cannot map a device for a crypto device.