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=head1 NAME
gpg - GNU Privacy Guard
=head1 SYNOPSIS
B<gpg> [--homedir name] [--options file] [options] command [args]
=head1 DESCRIPTION
B<gpg> is the main program for the GnuPG system.
=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<sigfile> 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 in a file without the
I<.sig> or I<.asc> extension (if such a file does
not exist it is expected at stdin - use B<-> as
filename to force a read 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 they 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<This command may be removed in the future!>
B<--list-keys> [I<names>]
B<--list-public-keys> [I<names>]
List all keys from the public keyrings, or just the
ones given on the command line.
B<--list-secret-keys> [I<names>]
List all keys from the secret keyrings, 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 additional output
of a line with the fingerprint. May also be combined
with B<--list-sigs> or B<--check-sigs>.
If this command is given twice, the fingerprints of all
secondary keys are listed too.
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<--edit-key> I<name>
Present a menu which enables you to do all key
related tasks:
B<sign>
Make a signature on key of user I<name>.
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>.
B<lsign>
Same as B<sign> but the signature is marked as
non-exportbale and will therefore never be used
by others. This may be used to make keys valid
only in the local environment.
B<revsig>
Revoke a signature. GnuPG asks for every
every signature which has been done by one of
teh secret keys, whether a revocation
certificate should be generated.
B<trust>
Change the owner trust value. This updates the
trust-db immediately and no save is required.
B<adduid>
Create an alternate user id.
B<deluid>
Delete an user id.
B<addkey>
Add a subkey to this key.
B<delkey>
Remove a subkey.
B<revkey>
Revoke a subkey.
B<expire>
Change the key expiration time. If a key is
selected, the time of this key will be changed.
With no selection the key expiration of the
primary key is changed.
B<passwd>
Change the passphrase of the secret key.
B<uid> I<n>
Toggle selection of user id with index I<n>.
Use 0 to deselect all.
B<key> I<n>
Toggle selection of subkey with index I<n>.
Use 0 to deselect all.
B<check>
Check all selected user ids.
B<pref>
List preferences.
B<toggle>
Toggle between public and secret key listing.
B<save>
Save all changes to the key rings and quit.
B<quit>
Quit the program without updating the
key rings.
The listing shows you the key with its secondary
keys and all user ids. Selected keys or user ids
are indicated by an asterisk. The trust value is
displayed with the primary key: the first is the
assigned owner trust and the second is the calculated
trust value. Letters are used for the values:
B<-> No ownertrust assigned / not yet calculated.
B<e> Trust calculation has failed.
B<q> Not enough information for calculation.
B<n> Never trust this key.
B<m> Marginally trusted.
B<f> Fully trusted.
B<u> Ultimately trusted
B<--delete-key>
Remove key from the public keyring
B<--delete-secret-key>
Remove key from the secret and public 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<--send-keys> [I<names>]
Same as B<--export> but sends the keys to a keyserver.
Option B<--keyserver> must be used to give the name
of this keyserver. Don't send your complete keyring
to a keyserver - select only those keys which are new
or changed by you.
B<--export-all> [I<names>]
Same as B<--export> but does also export keys which
are not compatible to OpenPGP.
B<--export-secret-keys> [I<names>]
Same as B<--export>, but does export the secret keys.
This is normally not very useful.
B<--import>, B<--fast-import>
Import/merge keys. The fast version does not build
the trustdb; this can be done at any time with the
command B<--update-trustdb>.
B<--recv-keys> I<key_IDs>
Import the keys with the given key IDs from a HKP
keyserver. Option B<--keyserver> must be used to
give the name of this keyserver.
B<--export-ownertrust>
List the assigned ownertrust values in ASCII format
for backup purposes
B<--import-ownertrust> [I<filename>]
Update the trustdb with the ownertrust values stored
in I<filename> (or stdin if not given); existing
values will be overwritten.
=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
required arguments. 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
from the secret keyring.
B<-r> I<name>, B<--recipient> I<name>
Encrypt for user id I<name>. If this option is not
specified, GnuPG asks for the user id.
B<--encrypt-to> I<name>
Same as B<--recipient> but this one is intended for
in the options file and may be used together with
an own user-id as an "encrypt-to-self". These keys
are only used when there are other recipients given
either by use of --recipient or by the asked user id.
No trust checking is performed for these user ids.
B<--no-encrypt-to>
Disable the use of all B<--encrypt-to> keys.
B<-v>, B<--verbose>
Give more information during processing. If used
twice, the input data is listed in detail.
B<-q>, B<--quiet>
Be somewhat more quiet in some cases.
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 (normally 6).
B<-t>, B<--textmode>
Use canonical text mode. If B<-t> (but not
B<--textmode>) is used together with armoring
and signing, this enables clearsigned messages.
This kludge is needed for PGP compatibility;
normally you would use B<--sign> or B<--clearsign>
to selected the type of the signature.
B<-n>, B<--dry-run>
Don't make any changes (not yet implemented).
B<-i>, B<--interactive>
Prompt before overwriting any files.
B<--batch>
Use 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<--keyserver> I<name>
Use I<name> to lookup keys which are not yet in
your keyring. This is only done while verifying
messages with signatures. The option is also
required for the command B<--send-keys> to
specify the keyserver to where the keys should
be send. All keyservers synchronize with each
other - so there is no need to send keys to more
than one server. Using the command
"host -l pgp.net | grep wwwkeys" gives you a
list of keyservers. Because there is load
balancing using round-robin-dns you may notice
that you get different key servers.
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.
The filename may be prefixed with a scheme:
"gnupg-ring:" is the default one.
"gnupg-gdbm:" may be used for a GDBM ring.
It might make sense to use it together with
B<--no-default-keyring>.
B<--secret-keyring> I<file>
Same as B<--keyring> but for the 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<--charset> I<name>
Set the name of the native character set. This is used
to convert some strings to proper UTF-8 encoding.
Valid values for I<name> are:
B<iso-8859-1> This is the default Latin 1 set.
B<iso-8859-2> The Latin 2 set.
B<koi8-r> The usual Russian set (rfc1489).
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<--logger-fd> I<n>
Write log output to file descriptor I<n> and not to stderr.
B<--no-comment>
Do not write comment packets. This option affects only
the generation of secret keys. Output of option packets
is disabled since version 0.4.2.
B<--comment> I<string>
Use I<string> as comment string in clear text signatures.
B<--default-comment>
Force to write the standard comment string in clear
text signatures. Use this to overwrite B<--comment>
from a config file.
B<--no-version>
Omit the version string in clear text signatures.
B<--emit-version>
Force to write the version string in clear text
signatures. Use this to overwrite a previous
B<--no-version> from a config file.
B<--notation-data>, B<-N> I<name>=<value>
Put the name value pair into the signature as notation data.
I<name> Must consists only of alphanumeric characters, digits
or the underscore; the first character muts not be a digit.
B<value> May be any printable string; it will encoded in UTF8,
so sou should have check that your B<--charset> is set right.
If you prefix I<name> with an exclamation mark, the notation
data will be flagged as critical. (rfc2440:5.2.3.15).
B<--set-policy-url> I<string>
Use I<string> as Policy URL for signatures (rfc2440:5.2.3.19).
If you prefix it with an exclamation mark, the policy URL
packet will be flagged as critical.
B<--set-filename> I<string>
Use I<string> as the name of file which is stored in
messages.
B<--completes-needed> I<n>
Number of completely trusted users to introduce a new
key signer (defaults to 1).
B<--marginals-needed> I<n>
Number of marginally trusted users to introduce a new
key signer (defaults to 3)
B<--max-cert-depth> I<n>
Maximum depth of a certification chain (default is 5).
B<--cipher-algo> I<name>
Use I<name> as cipher algorithm. Running the program
with the command B<--version> yields a list of supported
algorithms. If this is not used the cipher algorithm is
selected from the preferences stored with the key.
B<--digest-algo> I<name>
Use I<name> as message digest algorithm. Running the
program with the command B<--version> yields a list of
supported algorithms. Please note that using this
option may violate the OpenPGP requirement, that a
160 bit hash is to be used for DSA.
B<--s2k-cipher-algo> I<name>
Use I<name> as the cipher algorithm used to protect secret
keys. The default cipher is BLOWFISH. This cipher is
also used for conventional encryption if B<--cipher-algo>
is not given.
B<--s2k-digest-algo> I<name>
Use I<name> as the digest algorithm used to mangle the
passphrases. The default algorithm is RIPE-MD-160.
This digest algorithm is also used for conventional
encryption if B<--digest-algo> is not given.
B<--s2k-mode> I<number>
Selects how passphrases are mangled. A number of I<0>
uses the plain passphrase (which is not recommended),
a I<1> (default) adds a salt to the passphrase and
I<3> iterates the whole process a couple of times.
Unless -B<--rfc1991> is used, this mode is also used
for conventional encryption.
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. The default algorithm may
give better results because the window size is not limited
to 8K. If this is not used the OpenPGP behavior is used,
i.e. the compression algorithm is selected from the
preferences.
B<--throw-keyid>
Do not put the keyid into encrypted packets. This option
hides the receiver of the message and is a countermeasure
against traffic analysis. It may slow down the decryption
process because all available secret keys are tried.
B<--not-dash-escaped>
This option changes the behavior of cleartext signatures
so that they can be used for patch files. You should not
send such an armored file via email because all spaces
and line endings are hashed too. You can not use this
option for data which has 5 dashes at the beginning of a
line, patch files don't have this. A special armor header
line tells GnuPG about this cleartext signature option.
B<--escape-from-lines>
Because some mailers change lines starting with "From "
to ">From " it is good to handle such lines in a special
way when creating cleartext signatures. All other PGP
versions do it this way too. This option is not enabled
by default because it would violate rfc2440.
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<--rfc1991>
Try to be more RFC1991 (PGP 2.x) compliant.
B<--openpgp>
Reset all packet, cipher and digest options to OpenPGP
behavior. Use this option to reset all previous
options like B<--rfc1991>, B<--force-v3-sigs>, B<--s2k-*>,
B<--cipher-algo>, B<--digest-algo> and B<--compress-algo> to
OpenPGP compliant values.
B<--force-v3-sigs>
OpenPGP states that an implementation should generate
v4 signatures but PGP 5.x recognizes v4 signatures only
on key material. This options forces v3 signatures for
signatures on data.
B<--force-mdc>
Force the use of encryption with appended manipulation
code. This is always used with the newer cipher (those
with a blocksize greater than 64 bit).
B<--lock-once>
Lock the file the first time a lock is requested
and do not release the lock until the process
terminates.
B<--lock-multiple>
Release the locks every time a lock is no longer
needed. Use this to overwrite a previous B<--lock-once>
from a config file.
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 ASCII 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<--with-key-data>
Print key listings delimited by colons and print the public key data.
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 error codes 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 directory used instead of F<~/.gnupg>.
=head1 FILES
F<~/.gnupg/secring.gpg> The secret keyring
F<~/.gnupg/secring.gpg.lock> and the lock file
F<~/.gnupg/pubring.gpg> The public keyring
F<~/.gnupg/pubring.gpg.lock> and the lock file
F<~/.gnupg/trustdb.gpg> The trust database
F<~/.gnupg/trustdb.gpg.lock> and the lock file
F<~/.gnupg/options> May contain options
F</usr[/local]/share/gnupg/options.skel> Skeleton file
F</usr[/local]/lib/gnupg/> Default location for extensions
=head1 SEE ALSO
gpg(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 well.
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 memory pages. Locking memory pages prevents the
operating system from writing memory pages to disk. If you get no
warning message about insecure memory your operating system supports
locking without being root. The program drops root privileges as soon
as locked memory is allocated.
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