nettle-pbkdf2 - Command-line password-based key derivation tool.

       This  manual  page  was  originally  written  by  Magnus  Holmgren  <holmgren@debian.org>, for the Debian
       GNU/Linux system (but may be used by others).

Nettle 3.0                                          June 2014                                   NETTLE-PBKDF2(1)

       This  manual  page  documents  briefly  the  nettle-pbkdf2 command.  This manual page was written for the
       Debian GNU/Linux distribution because the original program does not have a manual page.

       nettle-pbkdf2  is  a  front-end  for  Nettle's  PBKDF2  (Password-Based  Key   Derivation   Function   2)
       implementation. PBKDF2 applies a pseudo-random function to a passphrase together with a salt, producing a
       derivedkey of arbitrary length. By iterating the process many times, feeding the output of each round as
       the  input of the next, brute-force cracking of the password is made to take correspondingly longer time.
       The use of a salt makes it harder to use  dictionaries  or  rainbow  tables.  As  computers  become  more
       powerful, the number of iterations can be increased without changing the rest of the algorithm.

       The pseudo-random function used by this tool is currently HMAC-SHA256.

       The  password  is read from standard input and the resulting derived key is written to standard output in
       groups of 16 hexadecimal digits, unless the --raw option is used. The salt and number of  iterations  are
       not included in the output.

       nettle-pbkdf2 - Command-line password-based key derivation tool.

       This program follows the usual GNU command line syntax, with long options starting with two dashes (`-').
       A summary of options is included below.

       -l,--length=length
              Desired output length in octets.

       --raw  Output derived key in raw binary format.

       --hex-salt
              Specifies that SALT is provided in hexadecimal format.

       --help Show summary of options.

       -V,--version
              Show version of program.

mkpasswd(1),https://en.wikipedia.org/wiki/PBKDF2

nettle-pbkdf2 [OPTIONS] SALT