NAME

       encode_keychange - produce the KeyChange string for SNMPv3

SYNOPSIS

       encode_keychange -t md5|sha1 [OPTIONS]

DESCRIPTION

       encode_keychange  produces  a  KeyChange  string  using  the  old  and  new passphrases as
       described in Section 5 of RFC 2274 "User-based Security Model (USM) for version 3  of  the
       Simple  Network  Management  Protocol  (SNMPv3)". -t option is mandatory and specifies the
       hash transform type to use.

       The transform is used to convert passphrase to master key for a given user  (Ku),  convert
       master key to the localized key (Kul), and to hash the old Kul with the random bits.

       Passphrases are obtained by examining a number of sources until success (in order listed):

              command line options (see -N and -O options below);

              the file $HOME/.snmp/passphrase.ek which should only contain two lines with old and
              new passphrase;

              standard input -or-  user input from the terminal.

OPTIONS

       -E [0x]<engineID> EngineID used for Kul generation.
              <engineID> is intepreted as a hex string when  preceded  by  0x,  otherwise  it  is
              treated as a text string. If no <engineID> is specified, it is constructed from the
              first IP address for the local host.

       -f     Force passphrases to be read from standard input.

       -h     Display the help message.

       -N "<new_passphrase>"
              Passphrase used to generate the new Ku.

       -O "<old_passphrase>"
              Passphrase used to generate the old Ku.

       -P     Turn off the prompt for passphrases when getting data from standard input.

       -v     Be verbose.

       -V     Echo passphrases to terminal.

SEE ALSO

       The localized key method is defined in RFC 2274, Sections  2.6  and  A.2,  and  originally
       documented in

              U.  Blumenthal,  N.  C.  Hien,  B.  Wijnen,  "Key Derivation for Network Management
              Applications", IEEE Network Magazine, April/May issue, 1997.