Installation guide

The best way, which provides high quality random data but takes a long time (several minutes per
gigabyte on most systems):
dd if=/dev/urandom of=<device>
Fastest way, which provides lower quality random data:
badblocks -c 10240 -s -w -t random -v <device>
29.4 .3. Format t he device as a dm-crypt /LUKS encrypt ed device
Warning
The command below will destroy any existing data on the device.
cryptsetup luksFormat <device>
Tip
For more information, read the cryptsetup(8) man page.
After supplying the passphrase twice the device will be formatted for use. To verify, use the following
command:
cryptsetup isLuks <device> && echo Success
To see a summary of the encryption information for the device, use the following command:
cryptsetup luksDump <device>
29.4 .4 . Creat e a mapping t o allow access t o t he device's decrypt ed cont ent s
To access the device's decrypted contents, a mapping must be established using the kernel
device-mapper.
It is useful to choose a meaningful name for this mapping. LUKS provides a UUID (Universally
Unique Identifier) for each device. This, unlike the device name (eg: /dev/sda3), is guaranteed to
remain constant as long as the LUKS header remains intact. To find a LUKS device's UUID, run the
following command:
cryptsetup luksUUID <device>
An example of a reliable, informative and unique mapping name would be luks-<uuid>, where
<uuid> is replaced with the device's LUKS UUID (eg: luks-50ec957a-5b5a-47ee-85e6-
f8085bbc97a8). This naming convention might seem unwieldy but is it not necessary to type it often.
cryptsetup luksOpen <device> <name>
Red Hat Ent erprise Linux 5 Inst allat ion G uide
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