1sha512hmac(8)            System Administrator's Manual           sha512hmac(8)
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NAME

6       sha512hmac - compute and check HMAC values
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SYNOPSIS

10       sha512hmac  [OPTIONS]  [-u  | -k keyfile | -K key] [-c file [-q] | file
11       [...] ]
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DESCRIPTION

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

22       As  a  safety  measure, the tool will always attempt to verify a previ‐
23       ously- computed HMAC over itself with the contents  of  a  second  file
24       (sha512hmac.hmac  for  sha512hmac,  and a similarly-named file for each
25       variation) before processing any other files, and  will  exit  with  an
26       error  if  the  second file either cannot be read or does not match the
27       computed value.
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OPTIONS

31       -c     Check that the HMAC values and names  listed  in  the  specified
32              file(s) are correct for the files which are available.  The for‐
33              mat of the files should match the output which the tool produces
34              when  computing  the values: a hex-encoded HMAC value and then a
35              filename, separated by whitespace.
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37       -q     Suppress any output when checking values.
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39       -d cfgdir
40              Specify the configuration  directory  to  be  used  by  the  NSS
41              library.  The default location is /etc/pki/nssdb.
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43       -h algorithm
44              Generate  the  HMAC value using a non-default hashing algorithm.
45              The default is determined by the name used to  invoke  the  tool
46              (sha1hmac, sha256hmac, etc.).  If no default can be derived this
47              way, the default  setting  will  be  sha512.   Specify  help  or
48              another invalid value to obtain a list of recognized algorithms.
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50       -u     Generate  an  unkeyed  checksum  instead of an HMAC.  The output
51              produced by the tool  should  then  be  comparable  to  that  of
52              sha1sum and related tools.
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54       -k filename
55              Use the contents of the specified file as the secret key used in
56              computing the HMAC values.  If no key file or text is specified,
57              a  hard-coded  default value is used.  This option should always
58              be used.
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60       -K text
61              Use the text of the argument as the secret key used in computing
62              the  HMAC  values.  If no key file or text is specified, a hard-
63              coded default value is used.
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65       -b     Process file contents in binary mode, marking output as such  by
66              prefixing filenames with *.  This option is not expected to have
67              any other meaningful effect.
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69       -t bits
70              Truncate HMAC values to a given length when computing or verify‐
71              ing them.
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73       -S     Generate  an HMAC over the tool itself and output it on standard
74              out.  This is a bootstrapping option which is not expected to be
75              used.
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77       -P     Attempt  to  pass all input files through prelink -y before pro‐
78              cessing their contents.  The tool always attempts to do so  when
79              computing or performing a self-check.
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EXAMPLES

84       Example output from sha1hmac, for files on the developer's system:
85         e64db5e8a9b8a40091e5302fa4de0bfc6c5d19d0  /etc/passwd
86         e7d93a2c70ec4d7720c6f2b033c1e5ea19f2d677  /etc/group
87         d732d6df77114ea6b81a43d64655f86b1e5ee925  /etc/services
88         ad92162bef979054a75d1f3510e6b05902bec641  /etc/hosts
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SEE ALSO

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

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

103       Nalin Dahyabhai <nalin@redhat.com>
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107hmaccalc 0.9.12                   2009/03/19                     sha512hmac(8)
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