NetBSD/sbin/cgdconfig/cgdconfig.8

.\" $NetBSD: cgdconfig.8,v 1.8 2002/10/13 01:30:29 elric Exp $
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Roland C. Dowdeswell.
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.Dd September 23, 2002
.Dt CGDCONFIG 8
.Os
.Sh NAME
.Nm cgdconfig
.Nd configuration utility for the cryptographic disk driver
.Sh SYNOPSIS
.Nm ""
.Op Fl nv
.Ar cgd dev
.Op Ar paramsfile
.Nm ""
.Fl C
.Op Fl nv
.Op Fl f Ar configfile
.Nm ""
.Fl U
.Op Fl nv
.Op Fl f Ar configfile
.Nm ""
.Fl g
.Op Fl nrv
.Op Fl i Ar ivmeth
.Op Fl k Ar kgmeth
.Op Fl o Ar outfile
.Ar alg
.Op Ar keylen
.Nm ""
.Fl s
.Op Fl nv
.Op Fl i Ar ivmeth
.Ar cgd
.Ar dev
.Ar alg
.Op Ar keylen
.Nm ""
.Fl u
.Op Fl nv
.Ar cgd
.Sh DESCRIPTION
.Nm
is used to configure and unconfigure cryptographic disk devices (cgds)
and to maintain the configuration files that are associated with them.
For more information about cgd see
.Xr cgd 4 .
.Pp
The options are as follows:
.Bl -tag -width configfilexxxx
.It Fl C
Configure all the devices listed in the cgd configuration file.
.It Fl f Ar configfile
Specify the configuration file explicitly, rather than defaulting to
.Pa /etc/cgd/cgd.conf .
.It Fl g
Generate a paramsfile (to stdout).
.It Fl i Ar ivmeth
Specify the IV method (default: encblkno).
.It Fl k Ar kgmeth
Specify the key generation method (default: pkcs5_pbkdf2).
.It Fl o Ar outfile
When generating a
.Ar paramsfile ,
store it in
.Ar outfile .
.It Fl s
Read the key from stdin.
.It Fl U
Unconfigure all the devices listed in the cgd configuration file.
.It Fl u
Unconfigure a cgd.
.It Fl V Ar vmeth
Specify the verification method (default: none).
.It Fl v
Be verbose.
May be specified multiple times.
.El
.Pp
For more information about the cryptographic algorithms and IV methods
supported, please refer to
.Xr cgd 4 .
.Ss Key Generation Methods
The Key Generation Method refers to how the key should be generated.
The methods and descriptions are as follows:
.Bl -tag -width indentxxxxxx
.It pkcs5_pbkdf2
This method requires a passphrase which is entered at configuration
time.
It is a salted hmac-based scheme detailed in
.Dq PKCS#5 v2.0: Password-Based Cryptography Standard ,
RSA Laboratories, March 25, 1999, pages 8-10.
PKCS #5 was also republished as RFC 2898.
.It randomkey
The method simply reads
.Pa /dev/random
and uses the resulting bits as the key.
It does not require a passphrase to be entered.
This method is typically used to present disk devices that do not
need to survive a reboot, such as the swap partition.
It is also handy to facilitate overwriting the contents of
a disk volume with meaningless data prior to use.
.El
.Ss Verification Method
The verification method is how
.Nm
determines if the passphrase that has been entered is correct.
If the newly configured disk fails to verify, then
.Nm
will ask for the passphrase again and re-configure the device.
The following verification methods are supported:
.Pp
.Bl -tag -width indentxxx
.It none
perform no verification.
.It disklabel
scan for a valid disklabel.
.El
.Ss /etc/cgd/cgd.conf
The file
.Pa /etc/cgd/cgd.conf
is used to configure
.Nm
if either of
.Fl C
or
.Fl U
are specified.
Each line of the file is composed of either two or three
tokens: cgd, target, and optional paramsfile.
.Pp
A
.Sq \&#
character is interpreted as a comment and indicated that the
rest of the line should be ignored.
A
.Sq \e
at the end of a line indicates that the next line is a continuation of
the current line.
.Pp
See
.Sx EXAMPLES
for an example of
.Pa /etc/cgd/cgd.conf .
.Ss Parameters File
The Parameters File contains the required information to generate the
key and configure a device.
These files are typically generated by with the
.Fl g
flag and not edited by hand.
When a device is configured the default parameters file is constructed
by taking the basename of the target disk and prepending
.Pa /etc/cgd/
to it.
E.g., if the target is
.Pa /dev/sd0h ,
then the default parameters file will be
.Pa /etc/cgd/sd0h .
.Pp
The parameters file contains a list of key-value pairs which are
specified one per line.
Comments and line continuation work in the same way as for
.Pa /etc/cgd/cgd.conf .
.Pp
The keys are as follows:
.Bl -tag -width indentxxxxxxx
.It algorithm
The cryptographic algorithm.
.It iv-method
The IV generation method.
.It keylength
The length of the key.
.It keygen_method
The method used to generate the key.
.It keygen_salt
If the keygen_method requires a salt, then this is the salt.
It is base64 encoded.
.It xor_key
If this is present, then it will be XOR'ed with the generated key before
the device is configured.
This can be used if the parameters file is
stored on separate removable media, e.g. USB mass storage, to ensure that
the generated key is immune to passphrase-guessing attacks.
It is not valuable unless the parameters file is stored on removable media.
It is base64 encoded.
.It verify_method
The verification method.
.El
.Sh FILES
.Bl -tag -width indentxxxxxxxxxxxxxxxxxx -compact
.It Pa /etc/cgd/
configuration directory, used to store paramsfiles.
.It Pa /etc/cgd/cgd.conf
cgd configuration file.
.El
.Sh EXAMPLES
To set up and configure a cgd that uses AES with a 192 bit key
in CBC mode with the IV Method
.Sq encblkno
(encrypted block number):
.Bd -literal
	# cgdconfig -g -o /etc/cgd/wd0e aes-cbc 192
	# cgdconfig cgd0 /dev/wd0e
	/dev/wd0e's passphrase:
.Ed
.Pp
To configure a cgd that uses Blowfish with a 200 bit key that it
reads from stdin:
.Bd -literal
	# cgdconfig -s cgd0 /dev/sd0h blowfish-cbc 200
.Ed
.Pp
An example
.Pa /etc/cgd/cgd.conf :
.Bd -literal
	#
	# /etc/cgd/cgd.conf
	# Configuration file for cryptographic disk devices
	#

	# cgd		target		[paramsfile]
	cgd0		/dev/wd0e
	cgd1		/dev/sd0h	/usr/local/etc/cgd/sd0h
.Ed
.Pp
Note that this will store the parameters file as
.Pa /etc/cgd/wd0e .
And use the entered passphrase to generate the key.
.Sh SEE ALSO
.Xr cgd 4
.Pp
.Dq PKCS #5 v2.0: Password-Based Cryptography Standard ,
RSA Laboratories, March 25, 1999.
.Sh HISTORY
The
.Nm
utility appeared in
.Nx 1.7 .
.Sh BUGS
Since
.Nm
uses
.Xr getpass 3
to read in the passphrase, it is limited to 128 characters.