gnupg: gpgv
9.2 Verify OpenPGP signatures
=============================
'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.
'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.
The program returns 0 if everything is fine, 1 if at least one
signature was bad, and other error codes for fatal errors.
9.2.1 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'.
9.2.2 Environment
-----------------
HOME
Used to locate the default home directory.
GNUPGHOME
If set directory used instead of "~/.gnupg".
9.2.3 FILES
-----------
~/.gnupg/trustedkeys.gpg
The default keyring with the allowed keys.
'gpg'(1)
Info Catalog
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