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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 ([On some platforms gpg2 is
installed under the name gpg]).
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 dictionary 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 filenames 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 implement 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 per-
fectly valid OpenPGP message, but one that cannot be read by the intended recipient.
There are dozens of variations of OpenPGP programs available, 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 recipients, 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 reason, you
are far better off using the --pgp6, --pgp7, or --pgp8 options. These options are safe as they do not force any particu-
lar 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 information. Note that you cannot abbreviate this command.
--help
-h Print a usage message summarizing the most useful command line options. Note that you cannot abbreviate this com-
mand.
--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). The key to be used for signing is chosen by default or
can be set with the --local-user and --default-key options.
--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. The key to be used for signing is chosen by
default or can be set with the --local-user and --default-key options.
--detach-sign
-b Make a detached signature.
--encrypt
-e Encrypt data. This option may be combined with --sign (for a signed and encrypted message), --symmetric (for a
message that may be decrypted via a secret key or a passphrase), or --sign and --symmetric 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 STDOUT (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 generating any out-
put. 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 denoting it in the above way.
--multifile
This modifies certain other commands to accept multiple 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 letters 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 signature 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 com-
mand "tsign").
--check-sigs
Same as --list-sigs, but the signatures are verified. Note that for performance reasons the revocation status of
a signing key is not shown.
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 successfully verified, a "-"
denotes a bad signature and a "%" is used if an error occurred while checking 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 subcommand "help" provides an overview on available commands. For a
detailed description, please see the Card HOWTO at http://www.gnupg.org/documentation/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 command.
--delete-key name
Remove key from the public keyring. In batch mode either --yes is required or the key must be specified by finger-
print. 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 fingerprint.
--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 speci-
fied 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 keyserver. Fingerprints may be used instead of key IDs. Option --key-
server 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. If no key IDs are given, gpg does nothing.
--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 --import-options
merge-only option which does not insert new keys but does only the merging of new signatures, user-IDs and sub-
keys.
--recv-keys key IDs
Import the keys with the given key IDs from a keyserver. 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 key-
servers 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 --keyserver must be used to give the name of this keyserver. Keyservers that
support different search methods allow using the syntax specified in "How to specify a user ID" below. Note that
different keyserver types support different search methods. Currently only LDAP supports them all.
--fetch-keys URIs
Retrieve keys located at the specified URIs. Note that different installations of GnuPG may support different pro-
tocols (HTTP, FTP, LDAP, etc.)
--update-trustdb
Do trust database maintenance. This command iterates over all keys and builds the Web of Trust. This is an inter-
active 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 interaction. 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 "ownertrust".
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 useful for backup purposes as these values are the only ones which
can't be re-created from a corrupted trustdb. Example:
gpg --export-ownertrust > otrust.txt
--import-ownertrust
Update the trustdb with the ownertrust values stored in files (or STDIN if not given); existing values will be
overwritten. In case of a severely damaged trustdb and if you have a recent backup of the ownertrust values (e.g.
in the file `otrust.txt', you may re-create the trustdb using these commands:
cd ~/.gnupg
rm trustdb.gpg
gpg --import-ownertrust < otrust.txt
--rebuild-keydb-caches
When updating from version 1.0.6 to 1.0.7 this command 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 count
Emit count random bytes of the given quality level 0, 1 or 2. If count is not given or zero, an endless sequence
of random bytes will be emitted. If used with --armor the output will be base64 encoded. 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 specification of
a key on the command line.
uid n Toggle selection of user ID or photographic user ID with index n. Use * to select all and 0 to deselect
all.
key n Toggle selection of subkey with index n. Use * to select all and 0 to deselect all.
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 sig-
nature), 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.
delsig Delete a signature. Note that it is not possible to retract a signature, once it has been send to the pub-
lic (i.e. to a keyserver). In that case you better use revsig.
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.
check Check the signatures on all selected user IDs.
adduid Create an additional 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).
showphoto
Display the selected photographic user ID.
deluid Delete a user ID or photographic user ID. Note that it is not possible 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.
revuid Revoke a user ID or photographic user ID.
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 pri-
mary over other regular user IDs.
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 keyserver.
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 (without the =value) prefixed with a minus sign removes all
notations with that name.
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 includ-
ing the implied preferences 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 signature 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.
When setting preferences, you should list the algorithms in the order which you'd like to see them used by
someone else when encrypting a message to your key. If you don't include 3DES, it will be automatically
added at the end. Note that there are many factors that go into choosing an algorithm (for example, your
key may not be the only recipient), and so the remote OpenPGP application being used to send to you may or
may not follow your exact chosen order for a given message. It will, however, only choose an algorithm
that is present on the preference list of every recipient key. See also the INTEROPERABILITY WITH OTHER
OPENPGP PROGRAMS section below.
addkey Add a subkey to this key.
addcardkey
Generate a subkey on a card and add it to this key.
keytocard
Transfer the selected secret subkey (or the primary key if no subkey 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 command 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 command only with the corresponding public key and make sure that the file given as argument is indeed
the backup to restore. You should then select 2 to restore as encryption 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.
revkey Revoke a subkey.
expire Change the key or subkey 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.
trust Change the owner trust value for the key. 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.
addrevoker
Add a designated revoker to the key. This takes one optional argument: "sensitive". If a designated revoker
is marked as sensitive, it will not be exported by default (see export-options).
passwd Change the passphrase of the secret key.
toggle Toggle between public and secret key listing.
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 validate, any signature that is superseded by a later signature,
revoked signatures, and signatures issued by keys that are not present 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 signing subkeys that may not currently have them. Cross-certification
signatures protect against a subtle attack against signing subkeys. See --require-cross-certification. All
new keys generated have this signature by default, so this option is only useful to bring older keys up to
date.
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. The primary user id is indicated by a
dot, and 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:
- 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 subcom-
mand "lsign" from --edit-key.
OPTIONS
gpg 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 character are ignored. Commands
may be put in this file too, but that is not generally useful as the command will execute automatically with every execu-
tion 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 interactive commands. --no-batch disables this option. Note that even
with a filename given on the command line, gpg might still need to read from STDIN (in particular if gpg figures
that the input is a detached signature and no data file has been specified). Thus if you do not want to feed data
via STDIN, you should connect STDIN to `/dev/null'.
--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 functions). 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-public-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 sub-
packets to list. If no argument is passed, list all subpackets. Defaults to no. This option is only mean-
ingful 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 verified. 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 signature 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 signature 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 meaning-
ful if pka-lookups is set.
--enable-dsa2
--disable-dsa2
Enable hash truncation for all DSA keys even for old DSA Keys up to 1024 bit. This is also the default with
--openpgp. Note that older versions of GnuPG also required this flag to allow the generation of DSA larger than
1024 bit.
--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"), "%v" for the single-character calculated validity
of the image being viewed (e.g. "f"), "%V" for the calculated validity as a string (e.g. "full"), 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 environment 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 this option is not used, the home directory defaults to `~/.gnupg'.
It is only recognized when given on the command line. It also overrides any home directory stated through the
environment variable `GNUPGHOME' or (on W32 systems) by means of the Registry entry HKCU\Software\GNU\GnuPG:Home-
Dir.
--pcsc-driver file
Use file to access the smartcard reader. The current default is `libpcsclite.so.1' for GLIBC based systems, `/Sys-
tem/Library/Frameworks/PCSC.framework/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 compres-
sion level of zlib (normally 6). --bzip2-compress-level sets the compression level for the BZIP2 compression algo-
rithm (defaulting to 6 as well). This is a different option from --compress-level since BZIP2 uses a significant
amount of memory for each additional compression level. -z sets both. A value of 0 for n disables compression.
--bzip2-decompress-lowmem
Use a different decompression method for BZIP2 compressed 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 compressed 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 problem. 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 specified, 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 "persona" 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 fin-
gerprint 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 finger-
print with the owner of the key in person, 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 verified (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 signatures 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 models 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 creating 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 evidence 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 "userATexample.com" form), and there are no userATexample.com keys on the local keyring. This
option takes any number of the following mechanisms, in the order they are to be tried:
cert Locate a key using DNS CERT, as specified in rfc4398.
pka Locate a key using DNS PKA.
ldap Using DNS Service Discovery, check the domain in question for any LDAP keyservers to use. If this fails,
attempt to locate the 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.
local Locate the key using the local keyrings. This mechanism allows to select the order a local key lookup is
done. Thus using '--auto-key-locate local'' is identical to --no-auto-key-locate.
nodefault
This flag disables the standard local key lookup, done before any of the mechanisms defined by the --auto-
key-locate are tried. The position of this mechanism in the list does not matter. It is not required if
local is also used.
--keyid-format short|0xshort|long|0xlong
Select how to display key IDs. "short" is the traditional 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:[//]key-
servername[: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 keyserver. 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 configuration 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://keys.gnupg.net uses round robin DNS to give a different 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 prefixed with a
`no-' to give the opposite meaning. 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 keyserver. 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 keyserver as revoked. Note
that not all keyservers differentiate between revoked and unrevoked keys, and for such keyservers this
option is meaningless. Note also that most keyservers do not have cryptographic verification of key revoca-
tions, 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 keyserver 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 signatures 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 verified 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 veri-
fied 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 signature being verified has a PKA record, then use the PKA informa-
tion 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 key-
servers, as they do not support retrieving keys by subkey id.
use-temp-files
On most Unix-like platforms, GnuPG communicates 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 multiple 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 performing multiple actions at the same time uses this timeout value per action. For exam-
ple, 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 keyservers. 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.
debug Turn on debug output in the keyserver helper program. Note that the details of debug output depends on
which keyserver helper program is being used, and in turn, on any libraries that the keyserver helper pro-
gram uses internally (libcurl, openldap, etc).
check-cert
Enable certificate checking if the keyserver presents one (for hkps or ldaps). Defaults to on.
ca-cert-file
Provide a certificate store to override the system default. Only necessary if check-cert is enabled, and
the keyserver is using a certificate that is not present in a system default certificate list.
Note that depending on the SSL library that the keyserver helper is built with, this may actually be a
directory or a file.
--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 signatures. Caching gives a much better performance in key listings.
However, if you suspect that your public keyring is not save against write modifications, 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
someone 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 malfunctions
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 settings.
--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 'GPG_AGENT_INFO''. This is only used when --use-agent has 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 proba-
bly use this. Improper usage of this option may lead to data and key corruption.
--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 config-
uration 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; how-
ever 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 simply warn about certain common permis-
sion problems. Do not assume that the lack of a warning means that your system is secure.
Note that the warning for unsafe --homedir permissions 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 suppress warnings about itself.
The --homedir permissions 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 signature" on the subkey
is present and valid. This protects against a subtle attack against subkeys that can sign. Defaults to
--require-cross-certification 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 generating 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 --hidden-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 countermeasure 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 values. 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-secret-key name
For hidden recipients GPG needs to know the keys to use for trial decryption. The key set with --default-key is
always tried first, but this is often not sufficient. This option allows to set more keys to be used for trial
decryption. Although any valid user-id specification may be used for name it makes sense to use at least the long
keyid to avoid ambiguities. Note that gpg-agent might pop up a pinentry for a lot keys to do the trial decryp-
tion. If you want to stop all further trial decryption you may use close-window button instead of the cancel but-
ton.
--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 or --hid-
den-recipient) and might come handy in case where an encrypted message contains a bogus key ID.
--skip-hidden-recipients
--no-skip-hidden-recipients
During decryption skip all anonymous recipients. This option helps in the case that people use the hidden recipi-
ents feature to hide there own encrypt-to key from others. If oneself has many secret keys this may lead to a
major annoyance because all keys are tried in turn to decrypt soemthing which was not really intended for it. The
drawback of this option is that it is currently not possible to decrypt a message which includes real anonymous
recipients.
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 format.
--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 sup-
ports various levels of compression, it is possible that the plaintext of a given message may be significantly
larger than the original 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 meaning. 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 man-
gles keys with multiple subkeys. 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 keyserver --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 signa-
tures that were issued by keys that are not present 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 meaning. 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 program 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 command, this option resets the passphrases for all exported subkeys
to empty. This is useful 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 useful 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.
--with-keygrip
Include the keygrip in the key listings.
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 converted back to whatever the local system uses. This option is useful when communicating
between two platforms that have different line ending conventions (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 messages. This
kludge is needed for command-line compatibility with command-line versions of PGP; normally 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 generate 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 --no-ask-sig-expire, and unsets --sig-policy-url, --sig-notation, and --sig-keyserver-url, as these fea-
tures cannot be used with v3 signatures. --no-force-v3-sigs disables this option. Defaults to no.
--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 message 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 available algorithms,
and use none to set no preference at all. This allows the user to safely override the algorithm chosen by the
recipient key preferences, as GPG will only select an algorithm that is usable by all recipients. 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 available algorithms,
and use none to set no preference at all. This allows the user to safely override the algorithm chosen by the
recipient key preferences, as GPG will only select an algorithm that is usable by all recipients. The most highly
ranked digest algorithm in this list is also 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 available algo-
rithms, and use none to set no preference at all. This allows the user to safely override the algorithm chosen by
the recipient key preferences, as GPG will only select an algorithm that is usable by all recipients. The most
highly ranked compression algorithm in this list is also 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 inclu-
sive, 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 section
below before using one of these options.
--gnupg
Use standard GnuPG behavior. This is essentially OpenPGP behavior (see --openpgp), but with some additional work-
arounds 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 compliant values. All PGP work-
arounds are disabled.
--rfc4880
Reset all packet, cipher and digest options to strict RFC-4880 behavior. Note that this is currently 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 --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 possible. This restricts you to the ciphers IDEA (if the IDEA plug-
in 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 --escape-from-lines --force-v3-sigs.
--pgp7 Set up all options to be as PGP 7 compliant as possible. This is identical to --pgp6 except that MDCs are not dis-
abled, 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 possible. PGP 8 is a lot closer to the OpenPGP standard than previ-
ous 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 decryption pass and therefore enables a
fast listing of the encryption keys.
-i
--interactive
Prompt before overwriting any files.
--debug-level level
Select the debug level for investigating problems. level may be a numeric value or by a keyword:
none No debugging at all. A value of less than 1 may be used instead of the keyword.
basic Some basic debug messages. A value between 1 and 2 may be used instead of the keyword.
advanced
More verbose debug messages. A value between 3 and 5 may be used instead of the keyword.
expert Even more detailed messages. A value between 6 and 8 may be used instead of the keyword.
guru All of the debug messages you can get. A value greater than 8 may be used instead of the keyword. The cre-
ation of hash tracing files is only enabled if the keyword is used.
How these messages are mapped to the actual debugging flags is not specified and may change with newer releases of this
program. They are however carefully selected to best aid in debugging.
--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.
--faked-system-time epoch
This option is only useful for testing; it sets the system time back or forth to epoch which is the number of sec-
onds elapsed since the year 1970. Alternatively epoch may be given as a full ISO time string (e.g.
"20070924T154812").
--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.
--log-file file
--logger-file file
Same as --logger-fd, except the logger data is written to file file. Note that --log-file is only implemented for
GnuPG-2.
--attribute-fd n
Write attribute subpackets to the file descriptor n. This is most useful for use with --status-fd, since the sta-
tus messages are needed to separate out the various subpackets from the stream delivered 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 signatures and ASCII armored messages or keys (see --armor). The
default behavior is not to use a comment string. --comment may be repeated multiple times to get multiple comment
strings. --no-comments removes all comments. It is a good idea to keep the length of a single comment below 60
characters to avoid problems with mail programs wrapping such lines. Note that comment lines, like all other
header lines, are not protected by the signature.
--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 notation data. name must consist only of printable characters or
spaces, and must contain a '@' character in the form keynameATdomain.com (substituting the appropriate key-
name 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 notation 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 fingerprint of the
primary key of the key making the signature, "%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-pol-
icy-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 a "secure viewer" with a claimed 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 algo-
rithms. 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-prefer-
ences 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 sup-
ported algorithms. In general, you do not want to use this option as it allows you to violate the OpenPGP stan-
dard. --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 com-
pression. 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 com-
pressing and decompressing. This may be significant in low memory situations. Note, however, that PGP (all ver-
sions) only supports ZIP compression. Using any algorithm other than ZIP or "none" will make the message unread-
able 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 pos-
sibly 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 algo-
rithm will still get disabled.
--disable-pubkey-algo name
Never allow the use of name as public key algorithm. 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. ([Using a little social engineering anyone who is able to decrypt
the message can check whether one of the other recipients is the one he suspects.]) On the receiving side, it may
slow down the decryption process because all available secret keys must be tried. --no-throw-keyids disables this
option. This option is essentially the same as using --hidden-recipient for all recipients.
--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.
--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 signature. 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 ques-
tions 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 associated with keys and signatures have plausible values. However,
sometimes a signature seems to be older than the key due to clock problems. This option makes these checks just a
warning. See also --ignore-valid-from for timestamp issues on subkeys.
--ignore-valid-from
GnuPG normally does not select and use subkeys created 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. Occasionally the CRC
gets mangled somewhere on the transmission channel but the actual content (which is protected by the OpenPGP pro-
tocol 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 par-
tially 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 appli-
cations 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
information, 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 someone forces you to reveal the con-
tent 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 expiration time. If this option is not specified, the expiration time
set via --default-sig-expire is used. --no-ask-sig-expire disables this option.
--default-sig-expire
The default expiration time to use for signature expiration. Valid values are "0" for no expiration, a number fol-
lowed 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 expiration 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 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".
--allow-secret-key-import
This is an obsolete option and is not used anywhere.
--allow-multiple-messages
--no-allow-multiple-messages
Allow processing of multiple OpenPGP messages contained in a single file or stream. Some programs that call GPG
are not prepared to deal with multiple messages being processed together, so this option defaults to no. Note
that versions of GPG prior to 1.4.7 always allowed multiple messages.
Warning: Do not use this option unless you need it as a temporary workaround!
--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 keyserver will be used as the keyserver URL when writing 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 programs that
call GnuPG to perform tasks, and is thus not generally useful. See the file `doc/DETAILS' in the source distribu-
tion 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 con-
figuration 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 configured when
GnuPG was built (generally "/usr/local/lib/gnupg"). Extensions are not generally 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 listings 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 current default is `libtowitoko.so'. Note that the use of this inter-
face 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 -u 0x12345678 -sb file
make a detached signature with the key 0x12345678
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 signatures,
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 certifi-
cate are the low 64 bits of its SHA-1 fingerprint. The use of key Ids is just a shortcut, for all automated pro-
cessing the fingerprint 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 available with gpgsm (i.e. the SHA-1 hash of the certificate).
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 hexadecimal 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 <heinrichhATuni-duesseldorf.de>
By exact match on an email address.
This is indicated by enclosing the email address in the usual way with left and right angles.
<heinrichhATuni-duesseldorf.de>
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 followed 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 keygrip 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, how-
ever 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 com-
mand line (see: [option --options]). You should backup this file.
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 configuration.
For internal purposes gpg creates and maintains a few other files; They all live in in the current home directory (see:
[option --homedir]). Only the gpg may modify these files.
~/.gnupg/secring.gpg
The secret keyring. You should backup this file.
~/.gnupg/secring.gpg.lock
The lock file for the secret keyring.
~/.gnupg/pubring.gpg
The public keyring. You should backup this file.
~/.gnupg/pubring.gpg.lock
The lock file for the public keyring.
~/.gnupg/trustdb.gpg
The trust database. There is no need to backup this file; it is better to backup the ownertrust values (see:
[option --export-ownertrust]).
~/.gnupg/trustdb.gpg.lock
The lock file for the trust database.
~/.gnupg/random_seed
A file used to preserve the state of the internal random pool.
/usr[/local]/share/gnupg/options.skel
The skeleton options file.
/usr[/local]/lib/gnupg/
Default location for extensions.
Operation is further controlled by a few environment variables:
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 delim-
ited 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 Reg-
istry. If used and set to 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 loaded. If it
can't be loaded the Registry is tried and as last resort the native Windows locale system is used.
BUGS
On older 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 supports 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 protect the saved memory, passphrases or other sensitive material may be recoverable
from it later.
Before you report a bug you should first search the mailing list archives for similar problems and second check whether
such a bug has already been reported to our bug tracker at http://bugs.gnupg.org .
SEE ALSO
gpgv(1),
The full documentation for this tool is maintained as a Texinfo manual. If GnuPG and the info program are properly
installed at your site, the command
info gnupg
should give you access to the complete manual including a menu structure and an index.
GnuPG 1.4.11 2010-10-21 GPG(1)
