Ubuntu Manpage: gpgv - Verify OpenPGP signatures

NAME

       gpgv - Verify OpenPGP signatures

SYNOPSIS

       gpgv [options] signed_files

DESCRIPTION

       gpgv is an OpenPGP signature verification tool.

       This  program  is  actually  a  stripped-down  version  of gpg which is only able to check
       signatures. It is somewhat smaller than the fully-blown gpg  and  uses  a  different  (and
       simpler) way to check that the public keys used to make the signature are valid. There are
       no configuration files and only a few options are implemented.

       gpgv assumes that all keys in the keyring are trustworthy.  That does also  mean  that  it
       does not check for expired or revoked keys.

       If   no   --keyring   option  is  given,  gpgv  looks  for  a  ``default''  keyring  named
       ‘trustedkeys.kbx’ (preferred) or ‘trustedkeys.gpg’ in the home directory of GnuPG,  either
       the  default  home  directory  or  the  one  set  by the --homedir option or the GNUPGHOME
       environment variable.  If any --keyring option is used, gpgv will not look for the default
       keyring.  The  --keyring option may be used multiple times and all specified keyrings will
       be used together.

RETURN VALUE

       The program returns 0 if everything is fine, 1 if at least  one  signature  was  bad,  and
       other error codes for fatal errors.

OPTIONS

gpgv recognizes these options:

--verbose
-v Gives more information during processing. If used twice, the input data is listed
in detail.

--quiet
-q Try to be as quiet as possible.

--keyring file
Add file to the list of keyrings. If file begins with a tilde and a slash, these
are replaced by the HOME directory. If the filename does not contain a slash, it is
assumed to be in the home-directory ("~/.gnupg" if --homedir is not used).

--output file
-o file
Write output to file; to write to stdout use -. This option can be used to get the
signed text from a cleartext or binary signature; it also works for detached
signatures, but in that case this option is in general not useful. Note that an
existing file will be overwritten.

--status-fd n
Write special status strings to the file descriptor n. See the file DETAILS in the
documentation for a listing of them.

--logger-fd n
Write log output to file descriptor n and not to stderr.

--log-file file
Same as --logger-fd, except the logger data is written to file file. Use
‘socket://’ to log to socket.

--ignore-time-conflict
GnuPG normally checks that the timestamps associated with keys and signatures have
plausible values. However, sometimes a signature seems to be older than the key due
to clock problems. This option turns these checks into warnings.

--homedir dir
Set the name of the home directory to dir. If this option is not used, the home
directory defaults to ‘~/.gnupg’. It is only recognized when given on the command
line. It also overrides any home directory stated through the environment variable
‘GNUPGHOME’ or (on Windows systems) by means of the Registry entry
HKCU\Software\GNU\GnuPG:HomeDir.

On Windows systems it is possible to install GnuPG as a portable application. In
this case only this command line option is considered, all other ways to set a home
directory are ignored.

To install GnuPG as a portable application under Windows, create an empty file
named ‘gpgconf.ctl’ in the same directory as the tool ‘gpgconf.exe’. The root of
the installation is then that directory; or, if ‘gpgconf.exe’ has been installed
directly below a directory named ‘bin’, its parent directory. You also need to
make sure that the following directories exist and are writable: ‘ROOT/home’ for
the GnuPG home and ‘ROOT/var/cache/gnupg’ for internal cache files.

--weak-digest name
Treat the specified digest algorithm as weak. Signatures made over weak digests
algorithms are normally rejected. This option can be supplied multiple times if
multiple algorithms should be considered weak. MD5 is always considered weak, and
does not need to be listed explicitly.

--enable-special-filenames
This option enables a mode in which filenames of the form ‘-&n’, where n is a non-
negative decimal number, refer to the file descriptor n and not to a file with that
name.

EXAMPLES

       gpgv pgpfile
       gpgv sigfile [datafile]
              Verify  the signature of the file. The second form is used for detached signatures,
              where sigfile is the  detached  signature  (either  ASCII-armored  or  binary)  and
              datafile  contains  the signed data; if datafile is "-" the signed data is expected
              on stdin; if datafile is not given the name of the file holding the signed data  is
              constructed by cutting off the extension (".asc", ".sig" or ".sign") from sigfile.

FILES

       ~/.gnupg/trustedkeys.gpg
              The default keyring with the allowed keys.

ENVIRONMENT

       HOME   Used to locate the default home directory.

       GNUPGHOME
              If set directory used instead of "~/.gnupg".