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GPG(1) GNU Privacy Guard GPG(1)
NAME
gpg - OpenPGP encryption and signing tool
SYNOPSIS
gpg [--homedir dir] [--options file] [options] command
[args]
DESCRIPTION
gpg is the OpenPGP part of the GNU Privacy Guard (GnuPG).
It is a tool to provide digital encryption and signing
services using the OpenPGP standard. gpg features complete
key management and all bells and whistles you can expect
from a decent OpenPGP implementation.
This is the standalone version of gpg. For desktop use
you should consider using gpg2.
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.
WARNINGS
Use a *good* password for your user account and a *good*
passphrase to protect your secret key. This passphrase is
the weakest part of the whole system. Programs to do dic-
tionary attacks on your secret keyring are very easy to
write and so you should protect your "~/.gnupg/" directory
very well.
Keep in mind that, if this program is used over a network
(telnet), it is *very* easy to spy out your passphrase!
If you are going to verify detached signatures, make sure
that the program knows about it; either give both file-
names on the command line or use '-' to specify stdin.
INTEROPERABILITY
GnuPG tries to be a very flexible implementation of the
OpenPGP standard. In particular, GnuPG implements many of
the optional parts of the standard, such as the SHA-512
hash, and the ZLIB and BZIP2 compression algorithms. It is
important to be aware that not all OpenPGP programs imple-
ment these optional algorithms and that by forcing their
use via the --cipher-algo, --digest-algo, --cert-digest-
algo, or --compress-algo options in GnuPG, it is possible
to create a perfectly valid OpenPGP message, but one that
cannot be read by the intended recipient.
There are dozens of variations of OpenPGP programs avail-
able, and each supports a slightly different subset of
these optional algorithms. For example, until recently,
no (unhacked) version of PGP supported the BLOWFISH cipher
algorithm. A message using BLOWFISH simply could not be
read by a PGP user. By default, GnuPG uses the standard
OpenPGP preferences system that will always do the right
thing and create messages that are usable by all recipi-
ents, regardless of which OpenPGP program they use. Only
override this safe default if you really know what you are
doing.
If you absolutely must override the safe default, or if
the preferences on a given key are invalid for some rea-
son, you are far better off using the --pgp6, --pgp7, or
--pgp8 options. These options are safe as they do not
force any particular algorithms in violation of OpenPGP,
but rather reduce the available algorithms to a "PGP-safe"
list.
COMMANDS
Commands are not distinguished from options except for the
fact that only one command is allowed.
gpg may be run with no commands, in which case it will
perform a reasonable action depending on the type of file
it is given as input (an encrypted message is decrypted, a
signature is verified, a file containing keys is listed).
Please remember that option as well as command parsing
stops as soon as a non-option is encountered, you can
explicitly stop parsing by using the special option --.
Commands not specific to the function
--version
Print the program version and licensing informa-
tion. Note that you cannot abbreviate this com-
mand.
--help
-h Print a usage message summarizing the most useful
command line options. Not that you cannot abbrevi-
ate this command.
--warranty
Print warranty information.
--dump-options
Print a list of all available options and commands.
Note that you cannot abbreviate this command.
Commands to select the type of operation
--sign
-s Make a signature. This command may be combined with
--encrypt (for a signed and encrypted message),
--symmetric (for a signed and symmetrically
encrypted message), or --encrypt and --symmetric
together (for a signed message that may be
decrypted via a secret key or a passphrase).
--clearsign
Make a clear text signature. The content in a clear
text signature is readable without any special
software. OpenPGP software is only needed to verify
the signature. Clear text signatures may modify
end-of-line whitespace for platform independence
and are not intended to be reversible.
--detach-sign
-b Make a detached signature.
--encrypt
-e Encrypt data. This option may be combined with
--sign (for a signed and encrypted message), --sym-
metric (for a message that may be decrypted via a
secret key or a passphrase), or --sign and --sym-
metric together (for a signed message that may be
decrypted via a secret key or a passphrase).
--symmetric
-c Encrypt with a symmetric cipher using a passphrase.
The default symmetric cipher used is CAST5, but may
be chosen with the --cipher-algo option. This
option may be combined with --sign (for a signed
and symmetrically encrypted message), --encrypt
(for a message that may be decrypted via a secret
key or a passphrase), or --sign and --encrypt
together (for a signed message that may be
decrypted via a secret key or a passphrase).
--store
Store only (make a simple RFC1991 literal data
packet).
--decrypt
-d Decrypt the file given on the command line (or
stdin if no file is specified) and write it to std-
out (or the file specified with --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.
--verify
Assume that the first argument is a signed file or
a detached signature and verify it without generat-
ing any output. With no arguments, the signature
packet is read from stdin. 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 ".sig" or ".asc"
extension. With more than 1 argument, the first
should be a detached signature and the remaining
files are the signed stuff. To read the signed
stuff from stdin, use '-' as the second filename.
For security reasons a detached signature cannot
read the signed material from stdin without denot-
ing it in the above way.
--multifile
This modifies certain other commands to accept mul-
tiple files for processing on the command line or
read from stdin with each filename on a separate
line. This allows for many files to be processed at
once. --multifile may currently be used along with
--verify, --encrypt, and --decrypt. Note that
--multifile --verify may not be used with detached
signatures.
--verify-files
Identical to --multifile --verify.
--encrypt-files
Identical to --multifile --encrypt.
--decrypt-files
Identical to --multifile --decrypt.
--list-keys
-k
--list-public-keys
List all keys from the public keyrings, or just the
keys given on the command line. -k is slightly
different from --list-keys in that it allows only
for one argument and takes the second argument as
the keyring to search. This is for command line
compatibility with PGP 2 and has been removed in
gpg2.
Avoid using the output of this command in scripts
or other programs as it is likely to change as
GnuPG changes. See --with-colons for a machine-
parseable key listing command that is appropriate
for use in scripts and other programs.
--list-secret-keys
-K List all keys from the secret keyrings, or just the
ones given on the command line. A # after the let-
ters sec means that the secret key is not usable
(for example, if it was created via --export-
secret-subkeys).
--list-sigs
Same as --list-keys, but the signatures are listed
too.
For each signature listed, there are several flags
in between the "sig" tag and keyid. These flags
give additional information about each signature.
From left to right, they are the numbers 1-3 for
certificate check level (see --ask-cert-level), "L"
for a local or non-exportable signature (see
--lsign-key), "R" for a nonRevocable signature (see
the --edit-key command "nrsign"), "P" for a signa-
ture that contains a policy URL (see --cert-policy-
url), "N" for a signature that contains a notation
(see --cert-notation), "X" for an eXpired signature
(see --ask-cert-expire), and the numbers 1-9 or "T"
for 10 and above to indicate trust signature levels
(see the --edit-key command "tsign").
--check-sigs
Same as --list-sigs, but the signatures are veri-
fied.
The status of the verification is indicated by a
flag directly following the "sig" tag (and thus
before the flags described above for --list-sigs).
A "!" indicates that the signature has been suc-
cessfully verified, a "-" denotes a bad signature
and a "%" is used if an error occured while check-
ing the signature (e.g. a non supported algorithm).
--fingerprint
List all keys (or the specified ones) along with
their fingerprints. This is the same output as
--list-keys but with the additional output of a
line with the fingerprint. May also be combined
with --list-sigs or --check-sigs. If this command
is given twice, the fingerprints of all secondary
keys are listed too.
--list-packets
List only the sequence of packets. This is mainly
useful for debugging.
--card-edit
Present a menu to work with a smartcard. The sub-
command "help" provides an overview on available
commands. For a detailed description, please see
the Card HOWTO at http://www.gnupg.org/documenta-
tion/howtos.html#GnuPG-cardHOWTO .
--card-status
Show the content of the smart card.
--change-pin
Present a menu to allow changing the PIN of a
smartcard. This functionality is also available as
the subcommand "passwd" with the --card-edit com-
mand.
--delete-key name
Remove key from the public keyring. In batch mode
either --yes is required or the key must be speci-
fied by fingerprint. This is a safeguard against
accidental deletion of multiple keys.
--delete-secret-key name
Remove key from the secret and public keyring. In
batch mode the key must be specified by finger-
print.
--delete-secret-and-public-key name
Same as --delete-key, but if a secret key exists,
it will be removed first. In batch mode the key
must be specified by fingerprint.
--export
Either export all keys from all keyrings (default
keyrings and those registered via option
--keyring), or if at least one name is given, those
of the given name. The new keyring is written to
stdout or to the file given with option --output.
Use together with --armor to mail those keys.
--send-keys key IDs
Similar to --export but sends the keys to a key-
server. Fingerprints may be used instead of key
IDs. Option --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.
--export-secret-keys
--export-secret-subkeys
Same as --export, but exports the secret keys
instead. This is normally not very useful and a
security risk. The second form of the command has
the special property to render the secret part of
the primary key useless; this is a GNU extension to
OpenPGP and other implementations can not be
expected to successfully import such a key. See
the option --simple-sk-checksum if you want to
import such an exported key with an older OpenPGP
implementation.
--import
--fast-import
Import/merge keys. This adds the given keys to the
keyring. The fast version is currently just a
synonym.
There are a few other options which control how
this command works. Most notable here is the
--keyserver-options merge-only option which does
not insert new keys but does only the merging of
new signatures, user-IDs and subkeys.
--recv-keys key IDs
Import the keys with the given key IDs from a key-
server. Option --keyserver must be used to give the
name of this keyserver.
--refresh-keys
Request updates from a keyserver for keys that
already exist on the local keyring. This is useful
for updating a key with the latest signatures, user
IDs, etc. Calling this with no arguments will
refresh the entire keyring. Option --keyserver must
be used to give the name of the keyserver for all
keys that do not have preferred keyservers set (see
--keyserver-options honor-keyserver-url).
--search-keys names
Search the keyserver for the given names. Multiple
names given here will be joined together to create
the search string for the keyserver. Option --key-
server must be used to give the name of this key-
server. Keyservers that support different search
methods allow using the syntax specified in "How to
specify a user ID" below. Note that different key-
server types support different search methods. Cur-
rently only LDAP supports them all.
--fetch-keys URIs
Retrieve keys located at the specified URIs. Note
that different installations of GnuPG may support
different protocols (HTTP, FTP, LDAP, etc.)
--update-trustdb
Do trust database maintenance. This command iter-
ates over all keys and builds the Web of Trust.
This is an interactive command because it may have
to ask for the "ownertrust" values for keys. The
user has to give an estimation of how far she
trusts the owner of the displayed key to correctly
certify (sign) other keys. GnuPG only asks for the
ownertrust value if it has not yet been assigned to
a key. Using the --edit-key menu, the assigned
value can be changed at any time.
--check-trustdb
Do trust database maintenance without user interac-
tion. From time to time the trust database must be
updated so that expired keys or signatures and the
resulting changes in the Web of Trust can be
tracked. Normally, GnuPG will calculate when this
is required and do it automatically unless --no-
auto-check-trustdb is set. This command can be used
to force a trust database check at any time. The
processing is identical to that of --update-trustdb
but it skips keys with a not yet defined "own-
ertrust".
For use with cron jobs, this command can be used
together with --batch in which case the trust
database check is done only if a check is needed.
To force a run even in batch mode add the option
--yes.
--export-ownertrust
Send the ownertrust values to stdout. This is use-
ful for backup purposes as these values are the
only ones which can't be re-created from a cor-
rupted trust DB.
--import-ownertrust
Update the trustdb with the ownertrust values
stored in files (or stdin if not given); existing
values will be overwritten.
--rebuild-keydb-caches
When updating from version 1.0.6 to 1.0.7 this com-
mand should be used to create signature caches in
the keyring. It might be handy in other situations
too.
--print-md algo
--print-mds
Print message digest of algorithm ALGO for all
given files or stdin. With the second form (or a
deprecated "*" as algo) digests for all available
algorithms are printed.
--gen-random 0|1|2
Emit count random bytes of the given quality level.
If count is not given or zero, an endless sequence
of random bytes will be emitted. PLEASE, don't use
this command unless you know what you are doing; it
may remove precious entropy from the system!
--gen-prime mode bits
Use the source, Luke :-). The output format is
still subject to change.
--enarmor
--dearmor
Pack or unpack an arbitrary input into/from an
OpenPGP ASCII armor. This is a GnuPG extension to
OpenPGP and in general not very useful.
How to manage your keys
This section explains the main commands for key management
--gen-key
Generate a new key pair. This command is normally
only used interactively.
There is an experimental feature which allows you
to create keys in batch mode. See the file
`doc/DETAILS' in the source distribution on how to
use this.
--gen-revoke name
Generate a revocation certificate for the complete
key. To revoke a subkey or a signature, use the
--edit command.
--desig-revoke name
Generate a designated revocation certificate for a
key. This allows a user (with the permission of the
keyholder) to revoke someone else's key.
--edit-key
Present a menu which enables you to do most of the
key management related tasks. It expects the spec-
ification of a key on the command line.
sign Make a signature on key of user name If the
key is not yet signed by the default user
(or the users given with -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 -u.
lsign Same as "sign" but the signature is marked
as non-exportable and will therefore never
be used by others. This may be used to make
keys valid only in the local environment.
nrsign Same as "sign" but the signature is marked
as non-revocable and can therefore never be
revoked.
tsign Make a trust signature. This is a signature
that combines the notions of certification
(like a regular signature), and trust (like
the "trust" command). It is generally only
useful in distinct communities or groups.
Note that "l" (for local / non-exportable), "nr"
(for non-revocable, and "t" (for trust) may be
freely mixed and prefixed to "sign" to create a
signature of any type desired.
revsig Revoke a signature. For every signature
which has been generated by one of the
secret keys, GnuPG asks whether a revocation
certificate should be generated.
trust Change the owner trust value. This updates
the trust-db immediately and no save is
required.
disable
enable Disable or enable an entire key. A disabled
key can not normally be used for encryption.
adduid Create an alternate user id.
addphoto
Create a photographic user id. This will
prompt for a JPEG file that will be embedded
into the user ID. Note that a very large
JPEG will make for a very large key. Also
note that some programs will display your
JPEG unchanged (GnuPG), and some programs
will scale it to fit in a dialog box (PGP).
deluid Delete a user id. Note that it is not pos-
sible to retract a user id, once it has been
send to the public (i.e. to a keyserver).
In that case you better use revuid.
delsig Delete a signature. Note that it is not pos-
sible to retract a signature, once it has
been send to the public (i.e. to a key-
server). In that case you better use
revsig.
revuid Revoke a user id.
addkey Add a subkey to this key.
addcardkey
Generate a key on a card and add it to this
key.
keytocard
Transfer the selected secret key (or the
primary key if no key has been selected) to
a smartcard. The secret key in the keyring
will be replaced by a stub if the key could
be stored successfully on the card and you
use the save command later. Only certain key
types may be transferred to the card. A sub
menu allows you to select on what card to
store the key. Note that it is not possible
to get that key back from the card - if the
card gets broken your secret key will be
lost unless you have a backup somewhere.
bkuptocard file
Restore the given file to a card. This com-
mand may be used to restore a backup key (as
generated during card initialization) to a
new card. In almost all cases this will be
the encryption key. You should use this com-
mand only with the corresponding public key
and make sure that the file given as argu-
ment is indeed the backup to restore. You
should then select 2 to restore as encryp-
tion key. You will first be asked to enter
the passphrase of the backup key and then
for the Admin PIN of the card.
delkey Remove a subkey (secondart key). Note that
it is not possible to retract a subkey, once
it has been send to the public (i.e. to a
keyserver). In that case you better use
revkey.
addrevoker
Add a designated revoker. This takes one
optional argument: "sensitive". If a desig-
nated revoker is marked as sensitive, it
will not be exported by default (see export-
options).
revkey Revoke a subkey.
expire Change the key expiration time. If a subkey
is selected, the expiration time of this
subkey will be changed. With no selection,
the key expiration of the primary key is
changed.
passwd Change the passphrase of the secret key.
primary
Flag the current user id as the primary one,
removes the primary user id flag from all
other user ids and sets the timestamp of all
affected self-signatures one second ahead.
Note that setting a photo user ID as primary
makes it primary over other photo user IDs,
and setting a regular user ID as primary
makes it primary over other regular user
IDs.
uid n Toggle selection of user id with index n.
Use 0 to deselect all.
key n Toggle selection of subkey with index n.
Use 0 to deselect all.
check Check all selected user ids.
showphoto
Display the selected photographic user id.
pref List preferences from the selected user ID.
This shows the actual preferences, without
including any implied preferences.
showpref
More verbose preferences listing for the
selected user ID. This shows the preferences
in effect by including the implied prefer-
ences of 3DES (cipher), SHA-1 (digest), and
Uncompressed (compression) if they are not
already included in the preference list. In
addition, the preferred keyserver and signa-
ture notations (if any) are shown.
setpref string
Set the list of user ID preferences to
string for all (or just the selected) user
IDs. Calling setpref with no arguments sets
the preference list to the default (either
built-in or set via --default-preference-
list), and calling setpref with "none" as
the argument sets an empty preference list.
Use gpg --version to get a list of available
algorithms. Note that while you can change
the preferences on an attribute user ID (aka
"photo ID"), GnuPG does not select keys via
attribute user IDs so these preferences will
not be used by GnuPG.
keyserver
Set a preferred keyserver for the specified
user ID(s). This allows other users to know
where you prefer they get your key from. See
--keyserver-options honor-keyserver-url for
more on how this works. Setting a value of
"none" removes an existing preferred key-
server.
notation
Set a name=value notation for the specified
user ID(s). See --cert-notation for more on
how this works. Setting a value of "none"
removes all notations, setting a notation
prefixed with a minus sign (-) removes that
notation, and setting a notation name (with-
out the =value) prefixed with a minus sign
removes all notations with that name.
toggle Toggle between public and secret key list-
ing.
clean Compact (by removing all signatures except
the selfsig) any user ID that is no longer
usable (e.g. revoked, or expired). Then,
remove any signatures that are not usable by
the trust calculations. Specifically, this
removes any signature that does not vali-
date, any signature that is superseded by a
later signature, revoked signatures, and
signatures issued by keys that are not pre-
sent on the keyring.
minimize
Make the key as small as possible. This
removes all signatures from each user ID
except for the most recent self-signature.
cross-certify
Add cross-certification signatures to sign-
ing subkeys that may not currently have
them. Cross-certification signatures protect
against a subtle attack against signing sub-
keys. See --require-cross-certification.
save Save all changes to the key rings and quit.
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 calcu-
lated trust value. Letters are used for the values:
- No ownertrust assigned / not yet calculated.
e Trust calculation has failed; probably due
to an expired key.
q Not enough information for calculation.
n Never trust this key.
m Marginally trusted.
f Fully trusted.
u Ultimately trusted.
--sign-key name
Signs a public key with your secret key. This is a
shortcut version of the subcommand "sign" from
--edit.
--lsign-key name
Signs a public key with your secret key but marks
it as non-exportable. This is a shortcut version of
the subcommand "lsign" from --edit-key.
OPTIONS
gpg comes features a bunch of options to control the exact
behaviour and to change the default configuration.
Long options can be put in an options file (default
"~/.gnupg/gpg.conf"). Short option names will not work -
for example, "armor" is a valid option for the options
file, while "a" is not. 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 char-
acter are ignored. Commands may be put in this file too,
but that is not generally useful as the command will exe-
cute automatically with every execution of gpg.
Please remember that option parsing stops as soon as a
non-option is encountered, you can explicitly stop parsing
by using the special option --.
How to change the configuration
These options are used to change the configuration and are
usually found in the option file.
--default-key name
Use name as the default key to sign with. If this
option is not used, the default key is the first
key found in the secret keyring. Note that -u or
--local-user overrides this option.
--default-recipient name
Use name as default recipient if option --recipient
is not used and don't ask if this is a valid one.
name must be non-empty.
--default-recipient-self
Use the default key as default recipient if option
--recipient is not used and don't ask if this is a
valid one. The default key is the first one from
the secret keyring or the one set with --default-
key.
--no-default-recipient
Reset --default-recipient and --default-recipient-
self.
-v, --verbose
Give more information during processing. If used
twice, the input data is listed in detail.
--no-verbose
Reset verbose level to 0.
-q, --quiet
Try to be as quiet as possible.
--batch
--no-batch
Use batch mode. Never ask, do not allow interac-
tive commands. --no-batch disables this option.
--no-tty
Make sure that the TTY (terminal) is never used for
any output. This option is needed in some cases
because GnuPG sometimes prints warnings to the TTY
even if --batch is used.
--yes Assume "yes" on most questions.
--no Assume "no" on most questions.
--list-options parameters
This is a space or comma delimited string that
gives options used when listing keys and signatures
(that is, --list-keys, --list-sigs, --list-public-
keys, --list-secret-keys, and the --edit-key func-
tions). Options can be prepended with a no- (after
the two dashes) to give the opposite meaning. The
options are:
show-photos
Causes --list-keys, --list-sigs, --list-pub-
lic-keys, and --list-secret-keys to display
any photo IDs attached to the key. Defaults
to no. See also --photo-viewer.
show-policy-urls
Show policy URLs in the --list-sigs or
--check-sigs listings. Defaults to no.
show-notations
show-std-notations
show-user-notations
Show all, IETF standard, or user-defined
signature notations in the --list-sigs or
--check-sigs listings. Defaults to no.
show-keyserver-urls
Show any preferred keyserver URL in the
--list-sigs or --check-sigs listings.
Defaults to no.
show-uid-validity
Display the calculated validity of user IDs
during key listings. Defaults to no.
show-unusable-uids
Show revoked and expired user IDs in key
listings. Defaults to no.
show-unusable-subkeys
Show revoked and expired subkeys in key
listings. Defaults to no.
show-keyring
Display the keyring name at the head of key
listings to show which keyring a given key
resides on. Defaults to no.
show-sig-expire
Show signature expiration dates (if any)
during --list-sigs or --check-sigs listings.
Defaults to no.
show-sig-subpackets
Include signature subpackets in the key
listing. This option can take an optional
argument list of the subpackets to list. If
no argument is passed, list all subpackets.
Defaults to no. This option is only meaning-
ful when using --with-colons along with
--list-sigs or --check-sigs.
--verify-options parameters
This is a space or comma delimited string that
gives options used when verifying signatures.
Options can be prepended with a `no-' to give the
opposite meaning. The options are:
show-photos
Display any photo IDs present on the key
that issued the signature. Defaults to no.
See also --photo-viewer.
show-policy-urls
Show policy URLs in the signature being ver-
ified. Defaults to no.
show-notations
show-std-notations
show-user-notations
Show all, IETF standard, or user-defined
signature notations in the signature being
verified. Defaults to IETF standard.
show-keyserver-urls
Show any preferred keyserver URL in the sig-
nature being verified. Defaults to no.
show-uid-validity
Display the calculated validity of the user
IDs on the key that issued the signature.
Defaults to no.
show-unusable-uids
Show revoked and expired user IDs during
signature verification. Defaults to no.
show-primary-uid-only
Show only the primary user ID during signa-
ture verification. That is all the AKA
lines as well as photo Ids are not shown
with the signature verification status.
pka-lookups
Enable PKA lookups to verify sender
addresses. Note that PKA is based on DNS,
and so enabling this option may disclose
information on when and what signatures are
verified or to whom data is encrypted. This
is similar to the "web bug" described for
the auto-key-retrieve feature.
pka-trust-increase
Raise the trust in a signature to full if
the signature passes PKA validation. This
option is only meaningful if pka-lookups is
set.
--enable-dsa2
--disable-dsa2
Enables new-style DSA keys which (unlike the old
style) may be larger than 1024 bit and use hashes
other than SHA-1 and RIPEMD/160. Note that very few
programs currently support these keys and signa-
tures from them.
--photo-viewer string
This is the command line that should be run to view
a photo ID. "%i" will be expanded to a filename
containing the photo. "%I" does the same, except
the file will not be deleted once the viewer exits.
Other flags are "%k" for the key ID, "%K" for the
long key ID, "%f" for the key fingerprint, "%t" for
the extension of the image type (e.g. "jpg"), "%T"
for the MIME type of the image (e.g. "image/jpeg"),
and "%%" for an actual percent sign. If neither %i
or %I are present, then the photo will be supplied
to the viewer on standard input.
The default viewer is "xloadimage -fork -quiet
-title 'KeyID 0x%k' stdin". Note that if your image
viewer program is not secure, then executing it
from GnuPG does not make it secure.
--exec-path string
Sets a list of directories to search for photo
viewers and keyserver helpers. If not provided,
keyserver helpers use the compiled-in default
directory, and photo viewers use the $PATH environ-
ment variable. Note, that on W32 system this value
is ignored when searching for keyserver helpers.
--keyring file
Add file to the current 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 GnuPG
home directory ("~/.gnupg" if --homedir or
$GNUPGHOME is not used).
Note that this adds a keyring to the current list.
If the intent is to use the specified keyring
alone, use --keyring along with --no-default-
keyring.
--secret-keyring file
Same as --keyring but for the secret keyrings.
--primary-keyring file
Designate file as the primary public keyring. This
means that newly imported keys (via --import or
keyserver --recv-from) will go to this keyring.
--trustdb-name file
Use file instead of the default trustdb. 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 GnuPG
home directory (`~/.gnupg' if --homedir or
$GNUPGHOME is not used).
--homedir dir
Set the name of the home directory to dir. If his
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 W32 systems) by means on the
Registry entry HKCU\Software\GNU\GnuPG:HomeDir.
--pcsc-driver file
Use file to access the smartcard reader. The cur-
rent default is `libpcsclite.so.1' for GLIBC based
systems, `/System/Library/Frameworks/PCSC.frame-
work/PCSC' for MAC OS X, `winscard.dll' for Windows
and `libpcsclite.so' for other systems.
--disable-ccid
Disable the integrated support for CCID compliant
readers. This allows to fall back to one of the
other drivers even if the internal CCID driver can
handle the reader. Note, that CCID support is only
available if libusb was available at build time.
--reader-port number_or_string
This option may be used to specify the port of the
card terminal. A value of 0 refers to the first
serial device; add 32768 to access USB devices. The
default is 32768 (first USB device). PC/SC or CCID
readers might need a string here; run the program
in verbose mode to get a list of available readers.
The default is then the first reader found.
--display-charset name
Set the name of the native character set. This is
used to convert some informational strings like
user IDs to the proper UTF-8 encoding. Note that
this has nothing to do with the character set of
data to be encrypted or signed; GnuPG does not
recode user-supplied data. If this option is not
used, the default character set is determined from
the current locale. A verbosity level of 3 shows
the chosen set. Valid values for name are:
iso-8859-1
This is the Latin 1 set.
iso-8859-2
The Latin 2 set.
iso-8859-15
This is currently an alias for the Latin 1
set.
koi8-r The usual Russian set (rfc1489).
utf-8 Bypass all translations and assume that the
OS uses native UTF-8 encoding.
--utf8-strings
--no-utf8-strings
Assume that command line arguments are given as
UTF8 strings. The default (--no-utf8-strings) is to
assume that arguments are encoded in the character
set as specified by --display-charset. These
options affect all following arguments. Both
options may be used multiple times.
--options file
Read options from file and do not try to read them
from the default options file in the homedir (see
--homedir). This option is ignored if used in an
options file.
--no-options
Shortcut for --options /dev/null. This option is
detected before an attempt to open an option file.
Using this option will also prevent the creation of
a `~/.gnupg' homedir.
-z n
--compress-level n
--bzip2-compress-level n
Set compression level to n for the ZIP and ZLIB
compression algorithms. The default is to use the
default compression level of zlib (normally 6).
--bzip2-compress-level sets the compression level
for the BZIP2 compression algorithm (defaulting to
6 as well). This is a different option from --com-
press-level since BZIP2 uses a significant amount
of memory for each additional compression level.
-z sets both. A value of 0 for n disables compres-
sion.
--bzip2-decompress-lowmem
Use a different decompression method for BZIP2 com-
pressed files. This alternate method uses a bit
more than half the memory, but also runs at half
the speed. This is useful under extreme low memory
circumstances when the file was originally com-
pressed at a high --bzip2-compress-level.
--mangle-dos-filenames
--no-mangle-dos-filenames
Older version of Windows cannot handle filenames
with more than one dot. --mangle-dos-filenames
causes GnuPG to replace (rather than add to) the
extension of an output filename to avoid this prob-
lem. This option is off by default and has no
effect on non-Windows platforms.
--ask-cert-level
--no-ask-cert-level
When making a key signature, prompt for a
certification level. If this option is not speci-
fied, the certification level used is set via
--default-cert-level. See --default-cert-level for
information on the specific levels and how they are
used. --no-ask-cert-level disables this option.
This option defaults to no.
--default-cert-level n
The default to use for the check level when signing
a key.
0 means you make no particular claim as to how
carefully you verified the key.
1 means you believe the key is owned by the person
who claims to own it but you could not, or did not
verify the key at all. This is useful for a "per-
sona" verification, where you sign the key of a
pseudonymous user.
2 means you did casual verification of the key. For
example, this could mean that you verified that the
key fingerprint and checked the user ID on the key
against a photo ID.
3 means you did extensive verification of the key.
For example, this could mean that you verified the
key fingerprint with the owner of the key in per-
son, and that you checked, by means of a hard to
forge document with a photo ID (such as a passport)
that the name of the key owner matches the name in
the user ID on the key, and finally that you veri-
fied (by exchange of email) that the email address
on the key belongs to the key owner.
Note that the examples given above for levels 2 and
3 are just that: examples. In the end, it is up to
you to decide just what "casual" and "extensive"
mean to you.
This option defaults to 0 (no particular claim).
--min-cert-level
When building the trust database, treat any signa-
tures with a certification level below this as
invalid. Defaults to 2, which disregards level 1
signatures. Note that level 0 "no particular claim"
signatures are always accepted.
--trusted-key long key ID
Assume that the specified key (which must be given
as a full 8 byte key ID) is as trustworthy as one
of your own secret keys. This option is useful if
you don't want to keep your secret keys (or one of
them) online but still want to be able to check the
validity of a given recipient's or signator's key.
--trust-model pgp|classic|direct|always|auto
Set what trust model GnuPG should follow. The mod-
els are:
pgp This is the Web of Trust combined with trust
signatures as used in PGP 5.x and later.
This is the default trust model when creat-
ing a new trust database.
classic
This is the standard Web of Trust as used in
PGP 2.x and earlier.
direct Key validity is set directly by the user and
not calculated via the Web of Trust.
always Skip key validation and assume that used
keys are always fully trusted. You generally
won't use this unless you are using some
external validation scheme. This option also
suppresses the "[uncertain]" tag printed
with signature checks when there is no evi-
dence that the user ID is bound to the key.
auto Select the trust model depending on whatever
the internal trust database says. This is
the default model if such a database already
exists.
--auto-key-locate parameters
--no-auto-key-locate
GnuPG can automatically locate and retrieve keys as
needed using this option. This happens when
encrypting to an email address (in the "user@exam-
ple.com" form), and there are no user@example.com
keys on the local keyring. This option takes any
number of the following arguments, in the order
they are to be tried:
cert locate a key using DNS CERT, as specified in
2538bis (currently in draft):
http://www.josefsson.org/rfc2538bis/
pka locate a key using DNS PKA.
ldap locate a key using the PGP Universal method
of checking "ldap://keys.(thedomain)".
keyserver
locate a key using whatever keyserver is
defined using the --keyserver option.
(keyserver URL)
In addition, a keyserver URL as used in the
--keyserver option may be used here to query
that particular keyserver.
--keyid-format short|0xshort|long|0xlong
Select how to display key IDs. "short" is the tra-
ditional 8-character key ID. "long" is the more
accurate (but less convenient) 16-character key ID.
Add an "0x" to either to include an "0x" at the
beginning of the key ID, as in 0x99242560.
--keyserver name
Use name as your keyserver. This is the server that
--recv-keys, --send-keys, and --search-keys will
communicate with to receive keys from, send keys
to, and search for keys on. The format of the name
is a URI: `scheme:[//]keyservername[:port]' The
scheme is the type of keyserver: "hkp" for the HTTP
(or compatible) keyservers, "ldap" for the LDAP
keyservers, or "mailto" for the Graff email key-
server. Note that your particular installation of
GnuPG may have other keyserver types available as
well. Keyserver schemes are case-insensitive. After
the keyserver name, optional keyserver configura-
tion options may be provided. These are the same as
the global --keyserver-options from below, but
apply only to this particular keyserver.
Most keyservers synchronize with each other, so
there is generally no need to send keys to more
than one server. The keyserver hkp://sub-
keys.pgp.net uses round robin DNS to give a differ-
ent keyserver each time you use it.
--keyserver-options name=value1
This is a space or comma delimited string that
gives options for the keyserver. Options can be
prepended with a `no-' to give the opposite mean-
ing. Valid import-options or export-options may be
used here as well to apply to importing (--recv-
key) or exporting (--send-key) a key from a key-
server. While not all options are available for all
keyserver types, some common options are:
include-revoked
When searching for a key with --search-keys,
include keys that are marked on the key-
server as revoked. Note that not all key-
servers differentiate between revoked and
unrevoked keys, and for such keyservers this
option is meaningless. Note also that most
keyservers do not have cryptographic verifi-
cation of key revocations, and so turning
this option off may result in skipping keys
that are incorrectly marked as revoked.
include-disabled
When searching for a key with --search-keys,
include keys that are marked on the key-
server as disabled. Note that this option is
not used with HKP keyservers.
auto-key-retrieve
This option enables the automatic retrieving
of keys from a keyserver when verifying sig-
natures made by keys that are not on the
local keyring.
Note that this option makes a "web bug" like
behavior possible. Keyserver operators can
see which keys you request, so by sending
you a message signed by a brand new key
(which you naturally will not have on your
local keyring), the operator can tell both
your IP address and the time when you veri-
fied the signature.
honor-keyserver-url
When using --refresh-keys, if the key in
question has a preferred keyserver URL, then
use that preferred keyserver to refresh the
key from. In addition, if auto-key-retrieve
is set, and the signature being verified has
a preferred keyserver URL, then use that
preferred keyserver to fetch the key from.
Defaults to yes.
honor-pka-record
If auto-key-retrieve is set, and the signa-
ture being verified has a PKA record, then
use the PKA information to fetch the key.
Defaults to yes.
include-subkeys
When receiving a key, include subkeys as
potential targets. Note that this option is
not used with HKP keyservers, as they do not
support retrieving keys by subkey id.
use-temp-files
On most Unix-like platforms, GnuPG communi-
cates with the keyserver helper program via
pipes, which is the most efficient method.
This option forces GnuPG to use temporary
files to communicate. On some platforms
(such as Win32 and RISC OS), this option is
always enabled.
keep-temp-files
If using `use-temp-files', do not delete the
temp files after using them. This option is
useful to learn the keyserver communication
protocol by reading the temporary files.
verbose
Tell the keyserver helper program to be more
verbose. This option can be repeated multi-
ple times to increase the verbosity level.
timeout
Tell the keyserver helper program how long
(in seconds) to try and perform a keyserver
action before giving up. Note that perform-
ing multiple actions at the same time uses
this timeout value per action. For example,
when retrieving multiple keys via --recv-
keys, the timeout applies separately to each
key retrieval, and not to the --recv-keys
command as a whole. Defaults to 30 seconds.
http-proxy=value
Set the proxy to use for HTTP and HKP key-
servers. This overrides the "http_proxy"
environment variable, if any.
max-cert-size
When retrieving a key via DNS CERT, only
accept keys up to this size. Defaults to
16384 bytes.
--completes-needed n
Number of completely trusted users to introduce a
new key signer (defaults to 1).
--marginals-needed n
Number of marginally trusted users to introduce a
new key signer (defaults to 3)
--max-cert-depth n
Maximum depth of a certification chain (default is
5).
--simple-sk-checksum
Secret keys are integrity protected by using a
SHA-1 checksum. This method is part of the upcoming
enhanced OpenPGP specification but GnuPG already
uses it as a countermeasure against certain
attacks. Old applications don't understand this
new format, so this option may be used to switch
back to the old behaviour. Using this option bears
a security risk. Note that using this option only
takes effect when the secret key is encrypted - the
simplest way to make this happen is to change the
passphrase on the key (even changing it to the same
value is acceptable).
--no-sig-cache
Do not cache the verification status of key signa-
tures. Caching gives a much better performance in
key listings. However, if you suspect that your
public keyring is not save against write modifica-
tions, you can use this option to disable the
caching. It probably does not make sense to disable
it because all kind of damage can be done if some-
one else has write access to your public keyring.
--no-sig-create-check
GnuPG normally verifies each signature right after
creation to protect against bugs and hardware mal-
functions which could leak out bits from the secret
key. This extra verification needs some time (about
115% for DSA keys), and so this option can be used
to disable it. However, due to the fact that the
signature creation needs manual interaction, this
performance penalty does not matter in most set-
tings.
--auto-check-trustdb
--no-auto-check-trustdb
If GnuPG feels that its information about the Web
of Trust has to be updated, it automatically runs
the --check-trustdb command internally. This may
be a time consuming process. --no-auto-check-
trustdb disables this option.
--use-agent
--no-use-agent
Try to use the GnuPG-Agent. With this option,
GnuPG first tries to connect to the agent before it
asks for a passphrase. --no-use-agent disables this
option.
--gpg-agent-info
Override the value of the environment variable been
given. Given that this option is not anymore used
by gpg2, it should be avoided if possible.
--lock-once
Lock the databases the first time a lock is
requested and do not release the lock until the
process terminates.
--lock-multiple
Release the locks every time a lock is no longer
needed. Use this to override a previous --lock-once
from a config file.
--lock-never
Disable locking entirely. This option should be
used only in very special environments, where it
can be assured that only one process is accessing
those files. A bootable floppy with a stand-alone
encryption system will probably use this. Improper
usage of this option may lead to data and key cor-
ruption.
--exit-on-status-write-error
This option will cause write errors on the status
FD to immediately terminate the process. That
should in fact be the default but it never worked
this way and thus we need an option to enable this,
so that the change won't break applications which
close their end of a status fd connected pipe too
early. Using this option along with --enable-
progress-filter may be used to cleanly cancel long
running gpg operations.
--limit-card-insert-tries n
With n greater than 0 the number of prompts asking
to insert a smartcard gets limited to N-1. Thus
with a value of 1 gpg won't at all ask to insert a
card if none has been inserted at startup. This
option is useful in the configuration file in case
an application does not know about the smartcard
support and waits ad infinitum for an inserted
card.
--no-random-seed-file
GnuPG uses a file to store its internal random pool
over invocations. This makes random generation
faster; however sometimes write operations are not
desired. This option can be used to achieve that
with the cost of slower random generation.
--no-greeting
Suppress the initial copyright message.
--no-secmem-warning
Suppress the warning about "using insecure memory".
--no-permission-warning
Suppress the warning about unsafe file and home
directory (--homedir) permissions. Note that the
permission checks that GnuPG performs are not
intended to be authoritative, but rather they sim-
ply warn about certain common permission problems.
Do not assume that the lack of a warning means that
your system is secure.
Note that the warning for unsafe --homedir permis-
sions cannot be suppressed in the gpg.conf file, as
this would allow an attacker to place an unsafe
gpg.conf file in place, and use this file to sup-
press warnings about itself. The --homedir permis-
sions warning may only be suppressed on the command
line.
--no-mdc-warning
Suppress the warning about missing MDC integrity
protection.
--require-secmem
--no-require-secmem
Refuse to run if GnuPG cannot get secure memory.
Defaults to no (i.e. run, but give a warning).
--require-cross-certification
--no-require-cross-certification
When verifying a signature made from a subkey,
ensure that the cross certification "back signa-
ture" on the subkey is present and valid. This
protects against a subtle attack against subkeys
that can sign. Defaults to --require-cross-certi-
fication for gpg.
--expert
--no-expert
Allow the user to do certain nonsensical or "silly"
things like signing an expired or revoked key, or
certain potentially incompatible things like gener-
ating unusual key types. This also disables certain
warning messages about potentially incompatible
actions. As the name implies, this option is for
experts only. If you don't fully understand the
implications of what it allows you to do, leave
this off. --no-expert disables this option.
Key related options
--recipient name
-r Encrypt for user id name. If this option or --hid-
den-recipient is not specified, GnuPG asks for the
user-id unless --default-recipient is given.
--hidden-recipient name
-R Encrypt for user ID name, but hide the key ID of
this user's key. This option helps to hide the
receiver of the message and is a limited counter-
measure against traffic analysis. If this option or
--recipient is not specified, GnuPG asks for the
user ID unless --default-recipient is given.
--encrypt-to name
Same as --recipient but this one is intended for
use in the options file and may be used with your
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 and even disabled keys can be used.
--hidden-encrypt-to name
Same as --hidden-recipient but this one is intended
for use in the options file and may be used with
your own user-id as a hidden "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 and even disabled keys can be
used.
--no-encrypt-to
Disable the use of all --encrypt-to and --hidden-
encrypt-to keys.
--group name=value1
Sets up a named group, which is similar to aliases
in email programs. Any time the group name is a
recipient (-r or --recipient), it will be expanded
to the values specified. Multiple groups with the
same name are automatically merged into a single
group.
The values are key IDs or fingerprints, but any key
description is accepted. Note that a value with
spaces in it will be treated as two different val-
ues. Note also there is only one level of expansion
--- you cannot make an group that points to another
group. When used from the command line, it may be
necessary to quote the argument to this option to
prevent the shell from treating it as multiple
arguments.
--ungroup name
Remove a given entry from the --group list.
--no-groups
Remove all entries from the --group list.
--local-user name
-u Use name as the key to sign with. Note that this
option overrides --default-key.
--try-all-secrets
Don't look at the key ID as stored in the message
but try all secret keys in turn to find the right
decryption key. This option forces the behaviour as
used by anonymous recipients (created by using
--throw-keyids) and might come handy in case where
an encrypted message contains a bogus key ID.
Input and Output
--armor
-a Create ASCII armored output. The default is to
create the binary OpenPGP format.
--no-armor
Assume the input data is not in ASCII armored for-
mat.
--output file
-o file
Write output to file.
--max-output n
This option sets a limit on the number of bytes
that will be generated when processing a file.
Since OpenPGP supports various levels of compres-
sion, it is possible that the plaintext of a given
message may be significantly larger than the origi-
nal OpenPGP message. While GnuPG works properly
with such messages, there is often a desire to set
a maximum file size that will be generated before
processing is forced to stop by the OS limits.
Defaults to 0, which means "no limit".
--import-options parameters
This is a space or comma delimited string that
gives options for importing keys. Options can be
prepended with a `no-' to give the opposite mean-
ing. The options are:
import-local-sigs
Allow importing key signatures marked as
"local". This is not generally useful unless
a shared keyring scheme is being used.
Defaults to no.
repair-pks-subkey-bug
During import, attempt to repair the damage
caused by the PKS keyserver bug (pre version
0.9.6) that mangles keys with multiple sub-
keys. Note that this cannot completely
repair the damaged key as some crucial data
is removed by the keyserver, but it does at
least give you back one subkey. Defaults to
no for regular --import and to yes for key-
server --recv-keys.
merge-only
During import, allow key updates to existing
keys, but do not allow any new keys to be
imported. Defaults to no.
import-clean
After import, compact (remove all signatures
except the self-signature) any user IDs from
the new key that are not usable. Then,
remove any signatures from the new key that
are not usable. This includes signatures
that were issued by keys that are not pre-
sent on the keyring. This option is the same
as running the --edit-key command "clean"
after import. Defaults to no.
import-minimal
Import the smallest key possible. This
removes all signatures except the most
recent self-signature on each user ID. This
option is the same as running the --edit-key
command "minimize" after import. Defaults
to no.
--export-options parameters
This is a space or comma delimited string that
gives options for exporting keys. Options can be
prepended with a `no-' to give the opposite mean-
ing. The options are:
export-local-sigs
Allow exporting key signatures marked as
"local". This is not generally useful unless
a shared keyring scheme is being used.
Defaults to no.
export-attributes
Include attribute user IDs (photo IDs) while
exporting. This is useful to export keys if
they are going to be used by an OpenPGP pro-
gram that does not accept attribute user
IDs. Defaults to yes.
export-sensitive-revkeys
Include designated revoker information that
was marked as "sensitive". Defaults to no.
export-reset-subkey-passwd
When using the --export-secret-subkeys com-
mand, this option resets the passphrases for
all exported subkeys to empty. This is use-
ful when the exported subkey is to be used
on an unattended machine where a passphrase
doesn't necessarily make sense. Defaults to
no.
export-clean
Compact (remove all signatures from) user
IDs on the key being exported if the user
IDs are not usable. Also, do not export any
signatures that are not usable. This
includes signatures that were issued by keys
that are not present on the keyring. This
option is the same as running the --edit-key
command "clean" before export except that
the local copy of the key is not modified.
Defaults to no.
export-minimal
Export the smallest key possible. This
removes all signatures except the most
recent self-signature on each user ID. This
option is the same as running the --edit-key
command "minimize" before export except that
the local copy of the key is not modified.
Defaults to no.
--with-colons
Print key listings delimited by colons. Note that
the output will be encoded in UTF-8 regardless of
any --display-charset setting. This format is use-
ful when GnuPG is called from scripts and other
programs as it is easily machine parsed. The
details of this format are documented in the file
`doc/DETAILS', which is included in the GnuPG
source distribution.
--fixed-list-mode
Do not merge primary user ID and primary key in
--with-colon listing mode and print all timestamps
as seconds since 1970-01-01.
--with-fingerprint
Same as the command --fingerprint but changes only
the format of the output and may be used together
with another command.
OpenPGP protocol specific options.
-t, --textmode
--no-textmode
Treat input files as text and store them in the
OpenPGP canonical text form with standard "CRLF"
line endings. This also sets the necessary flags to
inform the recipient that the encrypted or signed
data is text and may need its line endings con-
verted back to whatever the local system uses. This
option is useful when communicating between two
platforms that have different line ending conven-
tions (UNIX-like to Mac, Mac to Windows, etc).
--no-textmode disables this option, and is the
default.
If -t (but not --textmode) is used together with
armoring and signing, this enables clearsigned mes-
sages. This kludge is needed for command-line com-
patibility with command-line versions of PGP; nor-
mally you would use --sign or --clearsign to select
the type of the signature.
--force-v3-sigs
--no-force-v3-sigs
OpenPGP states that an implementation should gener-
ate v4 signatures but PGP versions 5 through 7 only
recognize v4 signatures on key material. This
option forces v3 signatures for signatures on data.
Note that this option implies --ask-sig-expire,
--sig-policy-url, --sig-notation, and --sig-key-
server-url, as these features cannot be used with
v3 signatures. --no-force-v3-sigs disables this
option.
--force-v4-certs
--no-force-v4-certs
Always use v4 key signatures even on v3 keys. This
option also changes the default hash algorithm for
v3 RSA keys from MD5 to SHA-1. --no-force-v4-certs
disables this option.
--force-mdc
Force the use of encryption with a modification
detection code. This is always used with the newer
ciphers (those with a blocksize greater than 64
bits), or if all of the recipient keys indicate MDC
support in their feature flags.
--disable-mdc
Disable the use of the modification detection code.
Note that by using this option, the encrypted mes-
sage becomes vulnerable to a message modification
attack.
--personal-cipher-preferences string
Set the list of personal cipher preferences to
string. Use gpg --version to get a list of avail-
able algorithms, and use none to set no preference
at all. This allows the user to factor in their
own preferred algorithms when algorithms are chosen
via recipient key preferences. The most highly
ranked cipher in this list is also used for the
--symmetric encryption command.
--personal-digest-preferences string
Set the list of personal digest preferences to
string. Use gpg --version to get a list of avail-
able algorithms, and use none to set no preference
at all. This allows the user to factor in their
own preferred algorithms when algorithms are chosen
via recipient key preferences. The most highly
ranked digest algorithm in this list is algo used
when signing without encryption (e.g. --clearsign
or --sign). The default value is SHA-1.
--personal-compress-preferences string
Set the list of personal compression preferences to
string. Use gpg --version to get a list of avail-
able algorithms, and use none to set no preference
at all. This allows the user to factor in their
own preferred algorithms when algorithms are chosen
via recipient key preferences. The most highly
ranked compression algorithm in this list is algo
used when there are no recipient keys to consider
(e.g. --symmetric).
--s2k-cipher-algo name
Use name as the cipher algorithm used to protect
secret keys. The default cipher is CAST5. This
cipher is also used for conventional encryption if
--personal-cipher-preferences and --cipher-algo is
not given.
--s2k-digest-algo name
Use name as the digest algorithm used to mangle the
passphrases. The default algorithm is SHA-1.
--s2k-mode n
Selects how passphrases are mangled. If n is 0 a
plain passphrase (which is not recommended) will be
used, a 1 adds a salt to the passphrase and a 3
(the default) iterates the whole process a number
of times (see --s2k-count). Unless --rfc1991 is
used, this mode is also used for conventional
encryption.
--s2k-count n
Specify how many times the passphrase mangling is
repeated. This value may range between 1024 and
65011712 inclusive, and the default is 65536. Note
that not all values in the 1024-65011712 range are
legal and if an illegal value is selected, GnuPG
will round up to the nearest legal value. This
option is only meaningful if --s2k-mode is 3.
Compliance options
These options control what GnuPG is compliant to. Only one
of these options may be active at a time. Note that the
default setting of this is nearly always the correct one.
See the INTEROPERABILITY WITH OTHER OPENPGP PROGRAMS sec-
tion below before using one of these options.
--gnupg
Use standard GnuPG behavior. This is essentially
OpenPGP behavior (see --openpgp), but with some
additional workarounds for common compatibility
problems in different versions of PGP. This is the
default option, so it is not generally needed, but
it may be useful to override a different compliance
option in the gpg.conf file.
--openpgp
Reset all packet, cipher and digest options to
strict OpenPGP behavior. Use this option to reset
all previous options like --s2k-*, --cipher-algo,
--digest-algo and --compress-algo to OpenPGP com-
pliant values. All PGP workarounds are disabled.
--rfc4880
Reset all packet, cipher and digest options to
strict RFC-4880 behavior. Note that this is cur-
rently the same thing as --openpgp.
--rfc2440
Reset all packet, cipher and digest options to
strict RFC-2440 behavior.
--rfc1991
Try to be more RFC-1991 (PGP 2.x) compliant.
--pgp2 Set up all options to be as PGP 2.x compliant as
possible, and warn if an action is taken (e.g.
encrypting to a non-RSA key) that will create a
message that PGP 2.x will not be able to handle.
Note that `PGP 2.x' here means `MIT PGP 2.6.2'.
There are other versions of PGP 2.x available, but
the MIT release is a good common baseline.
This option implies --rfc1991 --disable-mdc --no-
force-v4-certs --no-sk-comment --escape-from-lines
--force-v3-sigs --cipher-algo IDEA --digest-algo
MD5 --compress-algo ZIP. It also disables
--textmode when encrypting.
--pgp6 Set up all options to be as PGP 6 compliant as pos-
sible. This restricts you to the ciphers IDEA (if
the IDEA plugin is installed), 3DES, and CAST5, the
hashes MD5, SHA1 and RIPEMD160, and the compression
algorithms none and ZIP. This also disables
--throw-keyids, and making signatures with signing
subkeys as PGP 6 does not understand signatures
made by signing subkeys.
This option implies --disable-mdc --no-sk-comment
--escape-from-lines --force-v3-sigs.
--pgp7 Set up all options to be as PGP 7 compliant as pos-
sible. This is identical to --pgp6 except that MDCs
are not disabled, and the list of allowable ciphers
is expanded to add AES128, AES192, AES256, and
TWOFISH.
--pgp8 Set up all options to be as PGP 8 compliant as pos-
sible. PGP 8 is a lot closer to the OpenPGP stan-
dard than previous versions of PGP, so all this
does is disable --throw-keyids and set --escape-
from-lines. All algorithms are allowed except for
the SHA224, SHA384, and SHA512 digests.
Doing things one usually doesn't want to do.
-n
--dry-run
Don't make any changes (this is not completely
implemented).
--list-only
Changes the behaviour of some commands. This is
like --dry-run but different in some cases. The
semantic of this command may be extended in the
future. Currently it only skips the actual decryp-
tion pass and therefore enables a fast listing of
the encryption keys.
-i
--interactive
Prompt before overwriting any files.
--debug flags
Set debugging flags. All flags are or-ed and flags
may be given in C syntax (e.g. 0x0042).
--debug-all
Set all useful debugging flags.
--debug-ccid-driver
Enable debug output from the included CCID driver
for smartcards. Note that this option is only
available on some system.
--enable-progress-filter
Enable certain PROGRESS status outputs. This option
allows frontends to display a progress indicator
while gpg is processing larger files. There is a
slight performance overhead using it.
--status-fd n
Write special status strings to the file descriptor
n. See the file DETAILS in the documentation for a
listing of them.
--status-file file
Same as --status-fd, except the status data is
written to file file.
--logger-fd n
Write log output to file descriptor n and not to
stderr.
--logger-file file
Same as --logger-fd, except the logger data is
written to file file.
--attribute-fd n
Write attribute subpackets to the file descriptor
n. This is most useful for use with --status-fd,
since the status messages are needed to separate
out the various subpackets from the stream deliv-
ered to the file descriptor.
--attribute-file file
Same as --attribute-fd, except the attribute data
is written to file file.
--comment string
--no-comments
Use string as a comment string in clear text signa-
tures and ASCII armored messages or keys (see
--armor). The default behavior is not to use a com-
ment string. --comment may be repeated multiple
times to get multiple comment strings. --no-com-
ments removes all comments. It is a good idea to
keep the length of a single comment below 60 char-
acters to avoid problems with mail programs wrap-
ping such lines. Note that comment lines, like all
other header lines, are not protected by the signa-
ture.
--emit-version
--no-emit-version
Force inclusion of the version string in ASCII
armored output. --no-emit-version disables this
option.
--sig-notation name=value
--cert-notation name=value
-N, --set-notation name=value
Put the name value pair into the signature as nota-
tion data. name must consist only of printable
characters or spaces, and must contain a '@' char-
acter in the form keyname@domain.example.com (sub-
stituting the appropriate keyname and domain name,
of course). This is to help prevent pollution of
the IETF reserved notation namespace. The --expert
flag overrides the '@' check. value may be any
printable string; it will be encoded in UTF8, so
you should check that your --display-charset is set
correctly. If you prefix name with an exclamation
mark (!), the notation data will be flagged as
critical (rfc2440:5.2.3.15). --sig-notation sets a
notation for data signatures. --cert-notation sets
a notation for key signatures (certifications).
--set-notation sets both.
There are special codes that may be used in nota-
tion names. "%k" will be expanded into the key ID
of the key being signed, "%K" into the long key ID
of the key being signed, "%f" into the fingerprint
of the key being signed, "%s" into the key ID of
the key making the signature, "%S" into the long
key ID of the key making the signature, "%g" into
the fingerprint of the key making the signature
(which might be a subkey), "%p" into the finger-
print of the primary key of the key making the sig-
nature, "%c" into the signature count from the
OpenPGP smartcard, and "%%" results in a single
"%". %k, %K, and %f are only meaningful when making
a key signature (certification), and %c is only
meaningful when using the OpenPGP smartcard.
--sig-policy-url string
--cert-policy-url string
--set-policy-url string
Use string as a 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. --sig-policy-url sets a policy
url for data signatures. --cert-policy-url sets a
policy url for key signatures (certifications).
--set-policy-url sets both.
The same %-expandos used for notation data are
available here as well.
--sig-keyserver-url string
Use string as a preferred keyserver URL for data
signatures. If you prefix it with an exclamation
mark (!), the keyserver URL packet will be flagged
as critical.
The same %-expandos used for notation data are
available here as well.
--set-filename string
Use string as the filename which is stored inside
messages. This overrides the default, which is to
use the actual filename of the file being
encrypted.
--for-your-eyes-only
--no-for-your-eyes-only
Set the `for your eyes only' flag in the message.
This causes GnuPG to refuse to save the file unless
the --output option is given, and PGP to use the
"secure viewer" with a Tempest-resistant font to
display the message. This option overrides --set-
filename. --no-for-your-eyes-only disables this
option.
--use-embedded-filename
--no-use-embedded-filename
Try to create a file with a name as embedded in the
data. This can be a dangerous option as it allows
to overwrite files. Defaults to no.
--cipher-algo name
Use name as cipher algorithm. Running the program
with the command --version yields a list of
supported algorithms. If this is not used the
cipher algorithm is selected from the preferences
stored with the key. In general, you do not want to
use this option as it allows you to violate the
OpenPGP standard. --personal-cipher-preferences is
the safe way to accomplish the same thing.
--digest-algo name
Use name as the message digest algorithm. Running
the program with the command --version yields a
list of supported algorithms. In general, you do
not want to use this option as it allows you to
violate the OpenPGP standard. --personal-digest-
preferences is the safe way to accomplish the same
thing.
--compress-algo name
Use compression algorithm name. "zlib" is RFC-1950
ZLIB compression. "zip" is RFC-1951 ZIP compression
which is used by PGP. "bzip2" is a more modern
compression scheme that can compress some things
better than zip or zlib, but at the cost of more
memory used during compression and decompression.
"uncompressed" or "none" disables compression. If
this option is not used, the default behavior is to
examine the recipient key preferences to see which
algorithms the recipient supports. If all else
fails, ZIP is used for maximum compatibility.
ZLIB may give better compression results than ZIP,
as the compression window size is not limited to
8k. BZIP2 may give even better compression results
than that, but will use a significantly larger
amount of memory while compressing and decompress-
ing. This may be significant in low memory situa-
tions. Note, however, that PGP (all versions) only
supports ZIP compression. Using any algorithm other
than ZIP or "none" will make the message unreadable
with PGP. In general, you do not want to use this
option as it allows you to violate the OpenPGP
standard. --personal-compress-preferences is the
safe way to accomplish the same thing.
--cert-digest-algo name
Use name as the message digest algorithm used when
signing a key. Running the program with the command
--version yields a list of supported algorithms. Be
aware that if you choose an algorithm that GnuPG
supports but other OpenPGP implementations do not,
then some users will not be able to use the key
signatures you make, or quite possibly your entire
key.
--disable-cipher-algo name
Never allow the use of name as cipher algorithm.
The given name will not be checked so that a later
loaded algorithm will still get disabled.
--disable-pubkey-algo name
Never allow the use of name as public key algo-
rithm. The given name will not be checked so that
a later loaded algorithm will still get disabled.
--throw-keyids
--no-throw-keyids
Do not put the recipient key IDs into encrypted
messages. This helps to hide the receivers of the
message and is a limited countermeasure against
traffic analysis. On the receiving side, it may
slow down the decryption process because all avail-
able secret keys must be tried. --no-throw-keyids
disables this option. This option is essentially
the same as using --hidden-recipient for all recip-
ients.
--not-dash-escaped
This option changes the behavior of cleartext sig-
natures 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.
--escape-from-lines
--no-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
to prevent the mail system from breaking the signa-
ture. Note that all other PGP versions do it this
way too. Enabled by default. --no-escape-from-
lines disables this option.
--passphrase-repeat n
Specify how many times gpg will request a new
passphrase be repeated. This is useful for helping
memorize a passphrase. Defaults to 1 repetition.
--passphrase-fd n
Read the passphrase from file descriptor n. Only
the first line will be read from file descriptor n.
If you use 0 for n, the passphrase will be read
from stdin. This can only be used if only one
passphrase is supplied.
--passphrase-file file
Read the passphrase from file file. Only the first
line will be read from file file. This can only be
used if only one passphrase is supplied. Obviously,
a passphrase stored in a file is of questionable
security if other users can read this file. Don't
use this option if you can avoid it.
--passphrase string
Use string as the passphrase. This can only be used
if only one passphrase is supplied. Obviously, this
is of very questionable security on a multi-user
system. Don't use this option if you can avoid it.
--command-fd n
This is a replacement for the deprecated shared-
memory IPC mode. If this option is enabled, user
input on questions is not expected from the TTY but
from the given file descriptor. It should be used
together with --status-fd. See the file doc/DETAILS
in the source distribution for details on how to
use it.
--command-file file
Same as --command-fd, except the commands are read
out of file file
--allow-non-selfsigned-uid
--no-allow-non-selfsigned-uid
Allow the import and use of keys with user IDs
which are not self-signed. This is not recommended,
as a non self-signed user ID is trivial to forge.
--no-allow-non-selfsigned-uid disables.
--allow-freeform-uid
Disable all checks on the form of the user ID while
generating a new one. This option should only be
used in very special environments as it does not
ensure the de-facto standard format of user IDs.
--ignore-time-conflict
GnuPG normally checks that the timestamps associ-
ated with keys and signatures have plausible val-
ues. However, sometimes a signature seems to be
older than the key due to clock problems. This
option makes these checks just a warning. See also
--ignore-valid-from for timestamp issues on sub-
keys.
--ignore-valid-from
GnuPG normally does not select and use subkeys cre-
ated in the future. This option allows the use of
such keys and thus exhibits the pre-1.0.7
behaviour. You should not use this option unless
you there is some clock problem. See also --ignore-
time-conflict for timestamp issues with signatures.
--ignore-crc-error
The ASCII armor used by OpenPGP is protected by a
CRC checksum against transmission errors. Occasion-
ally the CRC gets mangled somewhere on the trans-
mission channel but the actual content (which is
protected by the OpenPGP protocol anyway) is still
okay. This option allows GnuPG to ignore CRC
errors.
--ignore-mdc-error
This option changes a MDC integrity protection
failure into a warning. This can be useful if a
message is partially corrupt, but it is necessary
to get as much data as possible out of the corrupt
message. However, be aware that a MDC protection
failure may also mean that the message was tampered
with intentionally by an attacker.
--no-default-keyring
Do not add the default keyrings to the list of
keyrings. Note that GnuPG will not operate without
any keyrings, so if you use this option and do not
provide alternate keyrings via --keyring or
--secret-keyring, then GnuPG will still use the
default public or secret keyrings.
--skip-verify
Skip the signature verification step. This may be
used to make the decryption faster if the signature
verification is not needed.
--with-key-data
Print key listings delimited by colons (like
--with-colons) and print the public key data.
--fast-list-mode
Changes the output of the list commands to work
faster; this is achieved by leaving some parts
empty. Some applications don't need the user ID and
the trust information given in the listings. By
using this options they can get a faster listing.
The exact behaviour of this option may change in
future versions. If you are missing some informa-
tion, don't use this option.
--no-literal
This is not for normal use. Use the source to see
for what it might be useful.
--set-filesize
This is not for normal use. Use the source to see
for what it might be useful.
--show-session-key
Display the session key used for one message. See
--override-session-key for the counterpart of this
option.
We think that Key Escrow is a Bad Thing; however
the user should have the freedom to decide whether
to go to prison or to reveal the content of one
specific message without compromising all messages
ever encrypted for one secret key. DON'T USE IT
UNLESS YOU ARE REALLY FORCED TO DO SO.
--override-session-key string
Don't use the public key but the session key
string. The format of this string is the same as
the one printed by --show-session-key. This option
is normally not used but comes handy in case some-
one forces you to reveal the content of an
encrypted message; using this option you can do
this without handing out the secret key.
--ask-sig-expire
--no-ask-sig-expire
When making a data signature, prompt for an expira-
tion time. If this option is not specified, the
expiration time set via --default-sig-expire is
used. --no-ask-sig-expire disables this option.
Note that by default, --force-v3-sigs is set which
also disables this option. If you want signature
expiration, you must set --no-force-v3-sigs as well
as turning --ask-sig-expire on.
--default-sig-expire
The default expiration time to use for signature
expiration. Valid values are "0" for no expiration,
a number followed by the letter d (for days), w
(for weeks), m (for months), or y (for years) (for
example "2m" for two months, or "5y" for five
years), or an absolute date in the form YYYY-MM-DD.
Defaults to "0".
--ask-cert-expire
--no-ask-cert-expire
When making a key signature, prompt for an expira-
tion time. If this option is not specified, the
expiration time set via --default-cert-expire is
used. --no-ask-cert-expire disables this option.
--default-cert-expire
The default expiration time to use for key signa-
ture expiration. Valid values are "0" for no expi-
ration, a number followed by the letter d (for
days), w (for weeks), m (for months), or y (for
years) (for example "2m" for two months, or "5y"
for five years), or an absolute date in the form
YYYY-MM-DD. Defaults to "0".
--allow-secret-key-import
This is an obsolete option and is not used any-
where.
--allow-multiple-messages
--no-allow-multiple-messages
Allow processing of multiple OpenPGP messages con-
tained in a single file or stream. Some programs
that call GPG are not prepared to deal with multi-
ple messages being processed together, so this
option defaults to no. Note that versions of GPG
prior to 1.4.7 always allowed multiple messages.
--enable-special-filenames
This options 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.
--no-expensive-trust-checks
Experimental use only.
--preserve-permissions
Don't change the permissions of a secret keyring
back to user read/write only. Use this option only
if you really know what you are doing.
--default-preference-list string
Set the list of default preferences to string. This
preference list is used for new keys and becomes
the default for "setpref" in the edit menu.
--default-keyserver-url name
Set the default keyserver URL to name. This key-
server will be used as the keyserver URL when writ-
ing a new self-signature on a key, which includes
key generation and changing preferences.
--list-config
Display various internal configuration parameters
of GnuPG. This option is intended for external pro-
grams that call GnuPG to perform tasks, and is thus
not generally useful. See the file `doc/DETAILS' in
the source distribution for the details of which
configuration items may be listed. --list-config is
only usable with --with-colons set.
--gpgconf-list
This command is similar to --list-config but in
general only internally used by the gpgconf tool.
--gpgconf-test
This is more or less dummy action. However it
parses the configuration file and returns with
failure if the configuration file would prevent gpg
from startup. Thus it may be used to run a syntax
check on the configuration file.
Deprecated options
--load-extension name
Load an extension module. If name does not contain
a slash it is searched for in the directory config-
ured when GnuPG was built (generally
"/usr/local/lib/gnupg"). Extensions are not gener-
ally useful anymore, and the use of this option is
deprecated.
--show-photos
--no-show-photos
Causes --list-keys, --list-sigs, --list-public-
keys, --list-secret-keys, and verifying a signature
to also display the photo ID attached to the key,
if any. See also --photo-viewer. These options are
deprecated. Use --list-options [no-]show-photos
and/or --verify-options [no-]show-photos instead.
--show-keyring
Display the keyring name at the head of key list-
ings to show which keyring a given key resides on.
This option is deprecated: use --list-options
[no-]show-keyring instead.
--ctapi-driver file
Use file to access the smartcard reader. The cur-
rent default is `libtowitoko.so'. Note that the use
of this interface is deprecated; it may be removed
in future releases.
--always-trust
Identical to --trust-model always. This option is
deprecated.
--show-notation
--no-show-notation
Show signature notations in the --list-sigs or
--check-sigs listings as well as when verifying a
signature with a notation in it. These options are
deprecated. Use --list-options [no-]show-notation
and/or --verify-options [no-]show-notation instead.
--show-policy-url
--no-show-policy-url
Show policy URLs in the --list-sigs or --check-sigs
listings as well as when verifying a signature with
a policy URL in it. These options are deprecated.
Use --list-options [no-]show-policy-url and/or
--verify-options [no-]show-policy-url instead.
EXAMPLES
gpg -se -r Bob file
sign and encrypt for user Bob
gpg --clearsign file
make a clear text signature
gpg -sb file
make a detached signature
gpg --list-keys user_ID
show keys
gpg --fingerprint user_ID
show fingerprint
gpg --verify pgpfile
gpg --verify sigfile
Verify the signature of the file but do not output
the data. The second form is used for detached sig-
natures, where sigfile is the detached signature
(either ASCII armored or binary) and are the signed
data; if this is not given, the name of the file
holding the signed data is constructed by cutting
off the extension (".asc" or ".sig") of sigfile or
by asking the user for the filename.
HOW TO SPECIFY A USER ID
There are different ways to specify a user ID to GnuPG.
Some of them are only valid for gpg others are only good
for gpgsm. Here is the entire list of ways to specify a
key:
By key Id.
This format is deduced from the length of the
string and its content or 0x prefix. The key Id of
an X.509 certificate are the low 64 bits of its
SHA-1 fingerprint. The use of key Ids is just a
shortcut, for all automated processing the finger-
print should be used.
When using gpg an exclamation mark (!) may be
appended to force using the specified primary or
secondary key and not to try and calculate which
primary or secondary key to use.
The last four lines of the example give the key ID
in their long form as internally used by the
OpenPGP protocol. You can see the long key ID using
the option --with-colons.
234567C4
0F34E556E
01347A56A
0xAB123456
234AABBCC34567C4
0F323456784E56EAB
01AB3FED1347A5612
0x234AABBCC34567C4
By fingerprint.
This format is deduced from the length of the
string and its content or the 0x prefix. Note,
that only the 20 byte version fingerprint is avail-
able with gpgsm (i.e. the SHA-1 hash of the cer-
tificate).
When using gpg an exclamation mark (!) may be
appended to force using the specified primary or
secondary key and not to try and calculate which
primary or secondary key to use.
The best way to specify a key Id is by using the
fingerprint. This avoids any ambiguities in case
that there are duplicated key IDs.
1234343434343434C434343434343434
123434343434343C3434343434343734349A3434
0E12343434343434343434EAB3484343434343434
0xE12343434343434343434EAB3484343434343434
(gpgsm also accepts colons between each pair of hexadeci-
mal digits because this is the de-facto standard on how to
present X.509 fingerprints.)
By exact match on OpenPGP user ID.
This is denoted by a leading equal sign. It does
not make sense for X.509 certificates.
=Heinrich Heine
By exact match on an email address.
This is indicated by enclosing the email address in
the usual way with left and right angles.
By word match.
All words must match exactly (not case sensitive)
but can appear in any order in the user ID or a
subjects name. Words are any sequences of letters,
digits, the underscore and all characters with bit
7 set.
+Heinrich Heine duesseldorf
By exact match on the subject's DN.
This is indicated by a leading slash, directly fol-
lowed by the RFC-2253 encoded DN of the subject.
Note that you can't use the string printed by
"gpgsm --list-keys" because that one as been
reordered and modified for better readability; use
--with-colons to print the raw (but standard
escaped) RFC-2253 string
/CN=Heinrich Heine,O=Poets,L=Paris,C=FR
By exact match on the issuer's DN.
This is indicated by a leading hash mark, directly
followed by a slash and then directly followed by
the rfc2253 encoded DN of the issuer. This should
return the Root cert of the issuer. See note
above.
#/CN=Root Cert,O=Poets,L=Paris,C=FR
By exact match on serial number and issuer's DN.
This is indicated by a hash mark, followed by the
hexadecimal representation of the serial number,
then followed by a slash and the RFC-2253 encoded
DN of the issuer. See note above.
#4F03/CN=Root Cert,O=Poets,L=Paris,C=FR
By keygrip
This is indicated by an ampersand followed by the
40 hex digits of a keygrip. gpgsm prints the key-
grip when using the command --dump-cert. It does
not yet work for OpenPGP keys.
&D75F22C3F86E355877348498CDC92BD21010A480
By substring match.
This is the default mode but applications may want
to explicitly indicate this by putting the asterisk
in front. Match is not case sensitive.
Heine
*Heine
Please note that we have reused the hash mark identifier
which was used in old GnuPG versions to indicate the so
called local-id. It is not anymore used and there should
be no conflict when used with X.509 stuff.
Using the RFC-2253 format of DNs has the drawback that it
is not possible to map them back to the original encoding,
however we don't have to do this because our key database
stores this encoding as meta data.
FILES
There are a few configuration files to control certain
aspects of gpg's operation. Unless noted, they are
expected in the current home directory (see: [option
--homedir]).
gpg.conf
This is the standard configuration file read by gpg
on startup. It may contain any valid long option;
the leading two dashes may not be entered and the
option may not be abbreviated. This default name
may be changed on the command line (see: [option
--options]).
Note that on larger installations, it is useful to put
predefined files into the directory `/etc/skel/.gnupg/' so
that newly created users start up with a working configu-
ration.
For internal purposes gpg creates and maintains a few
other files; They all live in in the current home direc-
tory (see: [option --homedir]). Only the gpg may modify
these files.
~/.gnupg/secring.gpg
The secret keyring.
~/.gnupg/secring.gpg.lock
and the lock file
~/.gnupg/pubring.gpg
The public keyring
~/.gnupg/pubring.gpg.lock
and the lock file
~/.gnupg/trustdb.gpg
The trust database
~/.gnupg/trustdb.gpg.lock
and the lock file
~/.gnupg/random_seed
used to preserve the internal random pool
/usr[/local]/share/gnupg/options.skel
Skeleton options file
/usr[/local]/lib/gnupg/
Default location for extensions
Operation is further controlled by a few environment vari-
ables:
HOME Used to locate the default home directory.
GNUPGHOME
If set directory used instead of "~/.gnupg".
GPG_AGENT_INFO
Used to locate the gpg-agent. This is only honored
when --use-agent is set. The value consists of 3
colon delimited fields: The first is the path to
the Unix Domain Socket, the second the PID of the
gpg-agent and the protocol version which should be
set to 1. When starting the gpg-agent as described
in its documentation, this variable is set to the
correct value. The option --gpg-agent-info can be
used to override it.
PINENTRY_USER_DATA
This value is passed via gpg-agent to pinentry. It
is useful to convey extra information to a custom
pinentry
COLUMNS
LINES Used to size some displays to the full size of the
screen.
LANGUAGE
Apart from its use by GNU, it is used in the W32
version to override the language selection done
through the Registry. If used and set to a a valid
and available language name (langid), the file with
the translation is loaded from
gpgdir/gnupg.nls/langid.mo. Here gpgdir is the
directory out of which the gpg binary has been
laoded. If it can't be loaded the Registry is
tried as a fallback.
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 (which may contain passphrases or
other sensitive material) to disk. If you get no warning
message about insecure memory your operating system sup-
ports locking without being root. The program drops root
privileges as soon as locked memory is allocated.
Note also that some systems (especially laptops) have the
ability to ``suspend to disk'' (also known as ``safe
sleep'' or ``hibernate''). This writes all memory to disk
before going into a low power or even powered off mode.
Unless measures are taken in the operating system to pro-
tect the saved memory, passphrases or other sensitive
material may be recoverable from it later.
SEE ALSO
gpgv(1),
The full documentation for this tool is maintained as a
Texinfo manual. If GnuPG and the info program are prop-
erly installed at your site, the command
info gnupg1
should give you access to the complete manual including a
menu structure and an index.
GnuPG 1.4.9 2008-08-19 GPG(1)