cryptsetup is an utility to setup a encrypted disks based on
dm-crypt module for 2.6 kernel.  dm-crypt uses a device-mapper
kernel infrastructure and the new Linux 2.6 cryptoapi to
provides transparent encryption of block devices. The user can
basically specify one of the symmetric ciphers, a key (of any
allowed size), and then he can create a new block device in
/dev/mapper. Writes to this device will be encrypted and reads
decrypted. You can mount your filesystem on it as usual. But
without the key you can't access your data.

cryptsetup does basically the same as cryptoloop for 2.4.x
kernels only that it's a much cleaner code and better suits
the need of a block device and has a more flexible
configuration interface. The on-disk format is also compatible.

• Nikolay A. Fetisov

• cryptsetup