sha512hmac(8)						   System Administrator's Manual					     sha512hmac(8)

NAME

       sha512hmac - compute and check HMAC values

SYNOPSIS

       sha512hmac [OPTIONS] [-u | -k keyfile | -K key] [-c file [-q] | file [...] ]

DESCRIPTION

       The  sha512hmac	command  can  compute  and/or  verify  HMAC  and  unkeyed  checksum  values for the contents of files.	Variations such as
       sha384hmac, sha256hmac, and sha1hmac all operate similarly except that they use different digest algorithms.

SELF-TEST
       As a safety measure, the tool will always attempt to verify a previously- computed HMAC over itself with the  contents  of  a  second  file
       (sha512hmac.hmac  for  sha512hmac,  and a similarly-named file for each variation) before processing any other files, and will exit with an
       error if the second file either cannot be read or does not match the computed value.

OPTIONS

       -c     Check that the HMAC values and names listed in the specified file(s) are correct for the files which are available.  The	format	of
	      the  files  should match the output which the tool produces when computing the values: a hex-encoded HMAC value and then a filename,
	      separated by whitespace.

       -q     Suppress any output when checking values.

       -d cfgdir
	      Specify the configuration directory to be used by the NSS library.  The default location is /etc/pki/nssdb.

       -h algorithm
	      Generate the HMAC value using a non-default hashing algorithm.  The default is determined by  the  name  used  to  invoke  the  tool
	      (sha1hmac,  sha256hmac,  etc.).  If no default can be derived this way, the default setting will be sha512.  Specify help or another
	      invalid value to obtain a list of recognized algorithms.

       -u     Generate an unkeyed checksum instead of an HMAC.	The output produced by the tool should then be comparable to that of  sha1sum  and
	      related tools.

       -k filename
	      Use  the contents of the specified file as the secret key used in computing the HMAC values.  If no key file or text is specified, a
	      hard-coded default value is used.  This option should always be used.

       -K text
	      Use the text of the argument as the secret key used in computing the HMAC values.  If no key file or text is specified, a hard-coded
	      default value is used.

       -b     Process file contents in binary mode, marking output as such by prefixing filenames with *.  This option is not expected to have any
	      other meaningful effect.

       -t bits
	      Truncate HMAC values to a given length when computing or verifying them.

       -S     Generate an HMAC over the tool itself and output it on standard out.  This is a bootstrapping option which is  not  expected  to	be
	      used.

       -P     Attempt to pass all input files through prelink -y before processing their contents.  The tool always attempts to do so when comput-
	      ing or performing a self-check.

EXAMPLES

       Example output from sha1hmac, for files on the developer's system:
	 e64db5e8a9b8a40091e5302fa4de0bfc6c5d19d0  /etc/passwd
	 e7d93a2c70ec4d7720c6f2b033c1e5ea19f2d677  /etc/group
	 d732d6df77114ea6b81a43d64655f86b1e5ee925  /etc/services
	 ad92162bef979054a75d1f3510e6b05902bec641  /etc/hosts

SEE ALSO

       fipshmac(1), fipscheck(1), prelink(8)

BUGS

       Probably, but let's hope not.  If you find any, please either report them in the bug database at  http://bugzilla.redhat.com/  against  the
       "hmaccalc" component, or in the trac instance at https://fedorahosted.org/hmaccalc/.

AUTHOR

       Nalin Dahyabhai <nalin@redhat.com>

hmaccalc 0.9.13 						    2009/03/19							     sha512hmac(8)