gnupg/doc/gpg.1pod

=head1 NAME

gpg - GNU Privacy Guard

=head1 SYNOPSIS

B<gpg> [--homedir name] [--options file] [options] command [args]
B<gpgm> [--homedir name] [--options file] [options] command [args]

=head1 DESCRIPTION

B<gpg> is the main program for the GNUPG system. B<gpgm> is a maintenance
tool which has some commands B<gpgm> does not have; it is there because
it does not handle sensitive data ans therefore has no need to allocate
secure memory.

=head1 COMMANDS

B<gpg> recognizes these commands:

B<-s>, B<--sign>
    Make a signature. This option may be combined
    with B<--encrypt>.

B<--clearsign>
    Make a clear text signature.

B<-b>, B<--detach-sign>
    Make a detached signature.

B<-e>, B<--encrypt>
    Encrypt data. This option may be combined with B<--sign>.

B<-c>, B<--symmetric>
    Encrypt with symmetric cipher only
    This command asks for a passphrase.

B<--store>
    store only (make a simple RFC1991 packet).

B<--decrypt> [I<file>]
    Decrypt file (or stdin if no file is specified) and
    write it to stdout (or the file specified with
    B<--output>). If the decrypted file is signed, the
    signature is also verified. This command differs
    from the default operation, as it never writes to the
    filename which is included in the file and it
    rejects files which don't begin with an encrypted
    message.

B<--verify> [[I<sigfile>] {I<signed-files>}]
    Assume that I<filename> is a signature and verify it
    without generating any output.  With no arguments,
    the signature packet is read from stdin (it may be a
    detached signature when not used in batch mode). If
    only a sigfile is given, it may be a complete signature
    or a detached signature, in which case the signed stuff
    is expected from stdin. With more than 1 argument, the
    first should be a detached signature and the remaining
    files are the signed stuff.

B<-k> [I<username>] [I<keyring>]
    Kludge to be somewhat compatible with PGP.
    Without arguments, all public keyrings are listed.
    With one argument, only I<keyring> is listed.
    Special combinations are also allowed, but it may
    give strange results when combined with more options.
    B<-kv>    Same as B<-k>
    B<-kvv>   List the signatures with every key.
    B<-kvvv>  Additionally check all signatures.
    B<-kvc>   List fingerprints
    B<-kvvc>  List fingerprints and signatures

B<--list-keys>	[I<names>]
    List all keys from the default public keyring, or just the ones
    given on the command line.

B<--list-sigs>	[I<names>]
    Same as B<--list-keys>, but the signatures are listed too.

B<--check-sigs> [I<names>]
    Same as B<--list-sigs>, but the signatures are verified.

B<--fingerprint> [I<names>]
    List all keys with their fingerprints. This is the
    same output as B<list-keys> but with the additonal output
    of a line with the fingerprint. May also be combined
    with B<--list-sigs> or B<--check-sigs>.

B<--list-packets>
    List only the sequence of packets. This is mainly
    useful for debugging.

B<--gen-key>
    Generate a new key pair. This command can only be
    used interactive.

B<--add-key> I<name>
    Add a subkey to an already existing key. This
    command is similiar to B<--gen-key> but a primary
    key must already exit.

B<--sign-key> I<name>
    Make a signature on key of user I<name>.
    This looks for the key, displays the key and checks
    all existing signatures of this key. If the key is
    not yet signed by the default user (or the users given
    with B<-u>), the program displays the information of
    the key again, together with its fingerprint and
    asks whether it should be signed. This question
    is repeated for all users specified with B<-u>.
    The key is then signed and the keyring which
    contains the key is updated.


B<--delete-key>
    Remove key from the public keyring

B<--delete-secret-key>
    Remove key from the secret and public keyring

B<--edit-key>
    Edit/remove a key signature.

B<--change-passphrase>
    Change the passphrase of your secret keyring

B<--gen-revoke>
    Generate a revocation certificate.

B<--export> [I<names>]
    Either export all keys from all keyrings (default
    keyrings and those registered via option B<--keyring>),
    or if at least one name is given, those of the given
    name. The new keyring is written to F<stdout> or to
    the file given with option "output".  Use together
    with B<-a> to mail those keys.

B<--import>
    import/merge keys

B<--list-ownertrust>
    List the assigned ownertrust values in ascii format for
    backup purposes [B<gpgm> only].

=head1 OPTIONS

Long options can be put in an options file (default F<~/.gnupg/options>);
do not write the 2 dashes, but simply the name of the option and any
arguments if required.	Lines with a hash as the first non-white-space
character are ignored. Commands may be put in this file too, but that
does not make sense.

B<gpg> recognizes these options:


B<-a>, B<--armor>
    Create ASCII armored output.

B<-o> I<file>, B<--output> I<file>
    Write output to I<file>.

B<-u> I<name>, B<--local-user> I<name>
    Use I<name> as the user-id to sign.
    This option is silently ignored for the list commands,
    so that it can be used in an options file.

B<--default-key>  I<name>
    Use I<name> as default user-id for signatures.  If this
    is not used the default user-id is the first user-id in
    the secret keyring.

B<-r>  I<name>, B<--remote-user>  I<name>
    Use I<name> as the user-id for encryption.
    This option is silently ignored for the list commands,
    so that it can be used in an options file.

B<-v>, B<--verbose>
    Give more information during processing. If used
    twice, the input data is listed in detail.


B<-z> I<n>
    Set compress level to I<n>. A value of 0 for I<n>
    disables compression. Default is to use the default
    compression level of zlib (which is 6).

B<-t>, B<--textmode>
    Use canonical text mode.  Used to make clear-text
    signatures.

B<-n>, B<--dry-run>
    Don't make any changes (not yet implemented).

B<--batch>
    Batch mode; never ask, do not allow interactive
    commands.

B<--no-batch>
    Disable batch mode; this may be used if B<batch>
    is used in the options file.

B<--yes>
    Assume yes on most questions.

B<--no>
    Assume no on most questions.

B<--keyring> I<file>
    Add I<file> to the list of keyrings.
    If I<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 (F<~/.gnupg> if B<--homedir>) is not used.

B<--secret-keyring> I<file>
    Same as B<--keyring> but for secret keyrings.


B<--homedir> I<dir>
    Set the name of the home directory to I<dir>. If this
    option is not used it defaults to F<~/.gnupg>. It does
    not make sense to use this in a options file. This
    also overrides the environment variable C<GNUPGHOME>.

B<--options> I<file>
    Read options from I<file> and do not try to read
    them from the default options file in the homedir
    (see B<--homedir>). This option is ignored when used
    in an options file.

B<--no-options>
    Shortcut for B<--options> I</dev/null>.  This option is
    detected before an attempt to open an option file.

B<--load-extension> I<modulename>
    Load an extension module. If I<modulename> does not
    contain a slash it is searched in B</usr/local/lib/gnupg>
    See the manual for more information about extensions.

B<--debug> I<flags>
    Set debugging flags. All flags are or-ed and I<flags> may
    be given in C syntax (e.g. 0x0042).

B<--debug-all>
    Set all useful debugging flags.

B<--status-fd> I<n>
    Write special status strings to the file descriptor I<n>.

B<--no-comment>
    Do not write comment packets.

B<--completes-needed> I<n>
    Number of completely trusted users to introduce a new
    key signator (defaults to 1).

B<--marginals-needed> I<n>
    Number of marginally trusted users to introduce a new
    key signator (defaults to 3)

B<--cipher-algo> I<name>
    Use I<name> as cipher algorithm. Running the program
    with the option B<--verbose> yields a list of supported
    algorithms.

B<--digest-algo> I<name>
    Use I<name> as message digest algorithm. Running the
    program with the option B<--verbose> yields a list of
    supported algorithms.

B<--compress-algo> I<number>
    Use compress algorithm I<number>. Default is I<2> which is
    RFC1950 compression; you may use I<1> to use the old zlib
    version which is used by PGP. This is only used for
    new messages. The default algorithm may give better
    results because the window size is not limited to 8K.

B<--passphrase-fd> I<n>
    Read the passphrase from file descriptor I<n>. If you use
    0 for I<n>, the passphrase will be read from stdin.  This
    can only be used if only one passphrase is supplied.
    B<Don't use this option if you can avoid it>

B<--no-verbose>
    Reset verbose level to 0.

B<--no-greeting>
    Suppress the initial copyright message but do not
    enter batch mode.

B<--no-armor>
    Assume the input data is not in ASCCI armored format.

B<--no-default-keyring>
    Do not add the default keyrings to the list of
    keyrings.

B<--skip-verify>
    Skip the signature verification step.  This may be used to
    make the encryption faster if the signature verification
    is not needed.

B<--version>
    Print version information along with a list
    of supported algorithms.

B<--with-colons>
    Print key listings delimited by colons.

B<--warranty>
    Print warranty information.

B<-h>, B<--help>
    Print usage information.


=head1 RETURN VALUE

The Program returns 0 if everything was fine, 1 if at least
a signature was bad and other errorcode for fatal errors.

=head1 EXAMPLES

  -se -r Bob [file]	     sign and encrypt for user Bob
  -sat [file]		     make a clear text signature
  -sb  [file]		     make a detached signature
  -k   [userid] 	     show keys
  -kc  [userid] 	     show fingerprint

=head1 ENVIRONMENT

C<HOME>       Used to locate the default home directory.
C<GNUPGHOME>  If set, direcory used instead of F<~/.gnupg>.

=head1 FILES

F<~/.gnupg/secring.gpg>     The secret keyring

F<~/.gnupg/pubring.gpg>     The public keyring

F<~/.gnupg/trustdb.gpg>     The trust database

F<~/.gnupg/options>	    May contain options

=head1 SEE ALSO

gpgm(1)  gpgd(1)


=head1 WARNINGS

Use a B<good> password for your user account and a B<good> passphrase
to protect your secret key.  This passphrase is the weakest part of the
whole system.  Programs to do dictionary attacks on your secret keyring
are very easy to write and so you should protect your B<~/.gnupg/>
directory very good.

Keep in mind that, if this program is used over a network (telnet), it
is B<very> easy to spy out your passphrase!

=head1 BUGS

On many systems this program should be installed as setuid(root); this
is necessary to lock some pages of memory. If you get no warning message
about insecure memory you have a nice OS kernel and you don't need to make
it setuid.