CGDCONFIG(8)            NetBSD System Manager's Manual            CGDCONFIG(8)

NAME
     cgdconfig -- configuration utility for the cryptographic disk driver

SYNOPSIS
     cgdconfig [-npv] [-V vmeth] cgd dev [paramsfile]
     cgdconfig -C [-nv] [-f configfile]
     cgdconfig -U [-nv] [-f configfile]
     cgdconfig -G [-nv] [-i ivmeth] [-k kgmeth] [-o outfile] paramsfile
     cgdconfig -g [-nv] [-i ivmeth] [-k kgmeth] [-o outfile] alg [keylen]
     cgdconfig -s [-nv] [-i ivmeth] cgd dev alg [keylen]
     cgdconfig -u [-nv] cgd

DESCRIPTION
     cgdconfig 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 cryptographic disk devices see cgd(4).

     The options are as follows:

     -C              Configure all the devices listed in the cgd configuration
                     file.

     -f configfile   Specify the configuration file explicitly, rather than
                     using the default configuration file /etc/cgd/cgd.conf.

     -G              Generate a new paramsfile (to stdout) using the values
                     from paramsfile which will generate the same key.  This
                     may need to prompt for multiple passphrases.

     -g              Generate a paramsfile (to stdout).

     -i ivmeth       Specify the IV method (default: encblkno1).

     -k kgmeth       Specify the key generation method (default:
                     pkcs5_pbkdf2/sha1).

     -o outfile      When generating a paramsfile, store it in outfile.

     -p              Read all passphrases from stdin rather than /dev/tty.
                     Passphrases are separated by newlines.  Users of this
                     flag must be able to predict the order in which
                     passphrases are prompted.  If this flag is specified then
                     verification errors will cause the device in question to
                     be unconfigured rather than prompting for the passphrase
                     again.

     -s              Read the key from stdin.

     -U              Unconfigure all the devices listed in the cgd configura-
                     tion file.

     -u              Unconfigure a cgd.

     -V vmeth        Specify the verification method (default: none).

     -v              Be verbose.  May be specified multiple times.

     For more information about the cryptographic algorithms and IV methods
     supported, please refer to cgd(4).

   Key Generation Methods
     To generate the key which it will use, cgdconfig evaluates all of the key
     generation methods in the parameters file and uses the exclusive-or of
     the outputs of all the methods.  The methods and descriptions are as fol-
     lows:

     pkcs5_pbkdf2/sha1  This method requires a passphrase which is entered at
                        configuration time.  It is a salted hmac-based scheme
                        detailed in ``PKCS#5 v2.0: Password-Based Cryptography
                        Standard'', RSA Laboratories, March 25, 1999, pages
                        8-10.  PKCS #5 was also republished as RFC 2898.

     pkcs5_pbkdf2       This is an earlier, slightly incorrect and deprecated
                        implementation of the above algorithm.  It is retained
                        for backwards compatibility with existing parameters
                        files, and will be removed.  Existing parameters files
                        should be converted to use the correct method using
                        the -G option, and a new passphrase.

     storedkey          This method stores its key in the parameters file.

     randomkey          The method simply reads /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 sur-
                        vive 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.

     urandomkey         The method simply reads /dev/urandom and uses the
                        resulting bits as the key.  This is similar to the
                        randomkey method, but it guarantees that cgdconfig
                        will not stall waiting for hard-random bits (useful
                        when configuring a cgd for swap at boot time).  Note,
                        however, that some or all of the bits used to generate
                        the key may be obtained from a pseudo-random number
                        generator, which may not be as secure as the entropy
                        based hard-random number generator.

     shell_cmd          This method executes a shell command via popen(3) and
                        reads the key from stdout.

   Verification Method
     The verification method is how cgdconfig determines if the generated key
     is correct.  If the newly configured disk fails to verify, then cgdconfig
     will regenerate the key and re-configure the device.  It only makes sense
     to specify a verification method if at least of the key generation meth-
     ods is error prone, e.g., uses a user-entered passphrase.  The following
     verification methods are supported:

     none       perform no verification.
     disklabel  scan for a valid disklabel.
     ffs        scan for a valid FFS file system.
     re-enter   prompt for passphrase twice, and ensure entered passphrases
                are identical.  This method only works with the
                pkcs5_pbkdf2/sha1 and pkcs5_pbkdf2 key generators.

   /etc/cgd/cgd.conf
     The file /etc/cgd/cgd.conf is used to configure cgdconfig if either of -C
     or -U are specified.  Each line of the file is composed of either two or
     three tokens: cgd, target, and optional paramsfile.

     A `#' character is interpreted as a comment and indicates that the rest
     of the line should be ignored.  A `\' at the end of a line indicates that
     the next line is a continuation of the current line.

     See EXAMPLES for an example of /etc/cgd/cgd.conf.

   Parameters File
     The Parameters File contains the required information to generate the key
     and configure a device.  These files are typically generated by the -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 /etc/cgd/ to it.  E.g., if the target is /dev/sd0h, then
     the default parameters file will be /etc/cgd/sd0h.

     It is possible to have more than one parameters file for a given disk
     which use different key generation methods but will generate the same
     key.  To create a parameters file that is equivalent to an existing
     parameters file, use cgdconfig with the -G flag.  See EXAMPLES for an
     example of this usage.

     The parameters file contains a list of statements each terminated with a
     semi-colon.  Some statements can contain statement-blocks which are
     either a single unadorned statement, or a brace-enclosed list of semi-
     colon terminated statements.  Three types of data are understood:

     integer    a 32 bit signed integer.
     string     a string.
     base64     a length-encoded base64 string.

     The following statements are defined:

     algorithm string
               Defines the cryptographic algorithm.

     iv-method string
               Defines the IV generation method.

     keylength integer
               Defines the length of the key.

     verify_method string
               Defines the verification method.

     keygen string statement_block
               Defines a key generation method.  The statement_block contains
               statements that are specific to the key generation method.

     The keygen statement's statement block may contain the following state-
     ments:

     key string
               The key.  Only used for the storedkey key generation method.

     cmd string
               The command to execute.  Only used for the shell_cmd key gener-
               ation method.

     iterations integer
               The number of iterations.  Only used for pkcs5_pbkdf2/sha1 and
               pkcs5_pbkdf2.

     salt base64
               The salt.  Only used for pkcs5_pbkdf2/sha1 and pkcs5_pbkdf2.

FILES
     /etc/cgd/                 configuration directory, used to store params-
                               files.
     /etc/cgd/cgd.conf         cgd configuration file.

EXAMPLES
     To set up and configure a cgd that uses AES with a 192 bit key in CBC
     mode with the IV Method `encblkno1' (encrypted block number):

             # cgdconfig -g -o /etc/cgd/wd0e aes-cbc 192
             # cgdconfig cgd0 /dev/wd0e
             /dev/wd0e's passphrase:

     When using verification methods, the first time that we configure the
     disk the verification method will fail.  We overcome this by supplying -V
     re-enter when we configure the first time to set up the disk.  Here is
     the sequence of commands that is recommended:

                  # cgdconfig -g -o /etc/cgd/wd0e -V disklabel aes-cbc
                  # cgdconfig -V re-enter cgd0 /dev/wd0e
                  /dev/wd0e's passphrase:
                  re-enter device's passphrase:
                  # disklabel -e -I cgd0
                  # cgdconfig -u cgd0
                  # cgdconfig cgd0 /dev/wd0e
                  /dev/wd0e's passphrase:

     To create a new parameters file that will generate the same key as an old
     parameters file:

                  # cgdconfig -G -o newparamsfile oldparamsfile
                  old file's passphrase:
                  new file's passphrase:

     To configure a cgd that uses Blowfish with a 200 bit key that it reads
     from stdin:

             # cgdconfig -s cgd0 /dev/sd0h blowfish-cbc 200

     An example parameters file which uses PKCS#5 PBKDF2:

             algorithm aes-cbc;
             iv-method encblkno1;
             keylength 128;
             verify_method none;
             keygen pkcs5_pbkdf2/sha1 {
                     iterations 39361;
                     salt AAAAgMoHiYonye6Kog \
                          dYJAobCHE=;
             };

     An example parameters file which stores its key locally:

             algorithm       aes-cbc;
             iv-method       encblkno1;
             keylength       256;
             verify_method   none;
             keygen storedkey key AAABAK3QO6d7xzLfrXTdsgg4 \
                                  ly2TdxkFqOkYYcbyUKu/f60L;

     An example /etc/cgd/cgd.conf:

             #
             # /etc/cgd/cgd.conf
             # Configuration file for cryptographic disk devices
             #

             # cgd           target          [paramsfile]
             cgd0            /dev/wd0e
             cgd1            /dev/sd0h       /usr/local/etc/cgd/sd0h

     Note that this will store the parameters file as /etc/cgd/wd0e.  And use
     the entered passphrase to generate the key.

DIAGNOSTICS
     cgdconfig: could not calibrate pkcs5_pbkdf2  An error greater than 5% in
     calibration occured.  This could be the result of dynamic processor fre-
     quency scaling technology.  Ensure that the processor clock frequency
     remains static throughout the program's execution.

SEE ALSO
     cgd(4)

     ``PKCS #5 v2.0: Password-Based Cryptography Standard'', RSA Laboratories,
     March 25, 1999.

HISTORY
     The cgdconfig utility appeared in NetBSD 2.0.

BUGS
     Since cgdconfig uses getpass(3) to read in the passphrase, it is limited
     to 128 characters.

NetBSD 5.0_STABLE             September 12, 2008             NetBSD 5.0_STABLE
