gnupg/doc/gpgv.texi

@c Copyright (C) 2004 Free Software Foundation, Inc.
@c This is part of the GnuPG manual.
@c For copying conditions, see the file GnuPG.texi.

@c
@c This is included by tools.texi.
@c

@include defs.inc

@manpage gpgv.1
@node gpgv
@section Verify OpenPGP signatures
@ifset manverb
.B gpgv
\- Verify OpenPGP signatures
@end ifset

@mansect synopsis
@ifset manverb
.B  gpgv
.RI [ options ]
.I sigfile
.RI [ datafiles ]
@end ifset

@mansect description
@code{@gpgvname} is an OpenPGP signature verification tool.

This program is actually a stripped-down version of @code{gpg} which is
only able to check signatures. It is somewhat smaller than the fully-blown
@code{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.

@code{@gpgvname} 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 @code{--keyring} option is given, @code{gpgv} looks for a
``default'' keyring named @file{trustedkeys.kbx} (preferred) or
@file{trustedkeys.gpg} in the home directory of GnuPG, either the
default home directory or the one set by the @code{--homedir} option
or the @code{GNUPGHOME} environment variable.  If any @code{--keyring}
option is used, @code{gpgv} will not look for the default keyring. The
@code{--keyring} option may be used multiple times and all specified
keyrings will be used together.

@noindent
@mansect options
@code{@gpgvname} recognizes these options:

@table @gnupgtabopt

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

@item --quiet
@itemx -q
@opindex quiet
Try to be as quiet as possible.

@item --keyring @var{file}
@opindex keyring
Add @var{file} to the list of keyrings.
If @var{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 @option{--homedir} is not used).

@item --output @var{file}
@itemx -o @var{file}
@opindex output
Write output to @var{file}; to write to stdout use @code{-}.  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.


@item --status-fd @var{n}
@opindex status-fd
Write special status strings to the file descriptor @var{n}.  See the
file DETAILS in the documentation for a listing of them.

@item --logger-fd @code{n}
@opindex logger-fd
Write log output to file descriptor @code{n} and not to stderr.

@item --log-file @code{file}
@opindex log-file
Same as @option{--logger-fd}, except the logger data is written to
file @code{file}.  Use @file{socket://} to log to socket.

@item --ignore-time-conflict
@opindex 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.

@include opt-homedir.texi

@item --weak-digest @code{name}
@opindex weak-digest
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.

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

@item --assert-pubkey-algo @var{algolist}
@opindex assert-pubkey-algo
This option works in the same way as described for @command{gpg}.

@end table

@mansect 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.

@mansect examples
@subsection Examples

@table @asis

@item @gpgvname @code{pgpfile}
@itemx @gpgvname @code{sigfile} [@code{datafile}]
Verify the signature of the file. The second form is used for detached
signatures, where @code{sigfile} is the detached signature (either
ASCII-armored or binary) and @code{datafile} contains the signed data;
if @code{datafile} is "-" the signed data is expected on
@code{stdin}; if @code{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 @code{sigfile}.

@end table

@mansect environment
@subsection Environment

@table @asis

@item HOME
Used to locate the default home directory.

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

@end table

@mansect files
@subsection FILES

Default keyring file is expected in the GnuPG home directory
(@pxref{option --homedir}, @code{GNUPGHOME}).

@table @file
@item ~/.gnupg/trustedkeys.kbx
@efindex trustedkeys.kbx
The default keyring with the allowed keys, using the new keybox format.

@item ~/.gnupg/trustedkeys.gpg
@efindex trustedkeys.gpg
When @file{trustedkeys.kbx} is not available, the default keyring with
the allowed keys, using a legacy format.

@end table

@mansect see also
@command{gpg}(1)
@include see-also-note.texi