Provided by: gnupg2_2.1.11-6ubuntu2.1_amd64 
NAME
gpg2 - OpenPGP encryption and signing tool
SYNOPSIS
gpg2 [--homedir dir] [--options file] [options] command [args]
DESCRIPTION
gpg2 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. gpg2 features complete key management and all bells and
whistles you can expect from a decent OpenPGP implementation.
In contrast to the standalone command gpg from GnuPG 1.x, which is might be better suited for server and
embedded platforms, the 2.x version is commonly installed under the name gpg2 and targeted to the desktop
as it requires several other modules to be installed.
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 perfectly 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 particular algorithms in violation of OpenPGP, but rather reduce the available
algorithms to a "PGP-safe" list.
COMMANDS
Commands are not distinguished from options except for the fact that only one command is allowed.
gpg2 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 command.
--warranty
Print warranty information.
--dump-options
Print a list of all available options and commands. Note that you cannot abbreviate this command.
Commands to select the type of operation
--sign
-s Make a signature. This command may be combined with --encrypt (for a signed and encrypted
message), --symmetric (for a signed and symmetrically encrypted message), or --encrypt and
--symmetric together (for a signed message that may be decrypted via a secret key or a
passphrase). 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 AES-128,
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 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 and verify it without generating any output. With
no arguments, the signature packet is read from STDIN. If only a one argument is given, it is
expected to be a complete signature.
With more than 1 argument, the first should be a detached signature and the remaining files ake up
the the signed data. To read the signed data 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.
Note: If the option --batch is not used, gpg2 may assume that a single argument is a file with a
detached signature and it will try to find a matching data file by stripping certain suffixes.
Using this historical feature to verify a detached signature is strongly discouraged; always
specify the data file too.
Note: When verifying a cleartext signature, gpg verifies only what makes up the cleartext signed
data and not any extra data outside of the cleartext signature or header lines following directly
the dash marker line. The option --output may be used to write out the actual signed data; but
there are other pitfalls with this format as well. It is suggested to avoid cleartext signatures
in favor of detached signatures.
--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.
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. This command has the same effect as using
--list-keys with --with-sig-list.
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 command
"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. This command has the same effect as using
--list-keys with --with-sig-check.
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).
--locate-keys
Locate the keys given as arguments. This command basically uses the same algorithm as used when
locating keys for encryption or signing and may thus be used to see what keys gpg2 might use. In
particular external methods as defined by --auto-key-locate may be used to locate a key. Only
public keys are listed.
--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. When used with option
--verbose the actual MPI values are dumped and not only their lengths.
--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
https://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-keys name
--delete-keys name
Remove key from the public keyring. In batch mode either --yes is required or the key must be
specified by fingerprint. This is a safeguard against accidental deletion of multiple keys.
--delete-secret-keys name
Remove key from the secret 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 specified by fingerprint.
--export
Either export all keys from all keyrings (default keyrings and those registered via option
--keyring), or if at least one name is given, those of the given name. The exported keys are
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 --keyserver must be used to give the name of this keyserver. Don't send your complete
keyring to a keyserver --- select only those keys which are new or changed by you. If no key IDs
are given, gpg does nothing.
--export-secret-keys
--export-secret-subkeys
Same as --export, but exports the secret keys instead. The exported keys are written to STDOUT or
to the file given with option --output. This command is often used along with the option --armor
to allow easy printing of the key for paper backup; however the external tool paperkey does a
better job for creating backups on paper. Note that exporting a secret key can be a security risk
if the exported keys are send over an insecure channel.
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. Its intended use is to generated a full key with an additional
signing subkey on a dedicated machine and then using this command to export the key without the
primary key to the main machine.
GnuPG may ask you to enter the passphrase for the key. This is required because the internal
protection method of the secret key is different from the one specified by the OpenPGP protocol.
--export-ssh-key
This command is used to export a key in the OpenSSH public key format. It requires the
specification of one key by the usual means and exports the latest valid subkey which has an
authentication capability to STDOUT or to the file given with option --output. That output can
directly be added to ssh's ‘authorized_key’ file.
By specifying the key to export using a key ID or a fingerprint suffixed with an exclamation mark
(!), a specific subkey or the primary key can be exported. This does not even require that the
key has the authentication capability flag set.
--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 subkeys.
--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 keyservers set (see --keyserver-options honor-keyserver-url).
--search-keys names
Search the keyserver for the given names. Multiple names given here will be joined together to
create the search string for the keyserver. Option --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 protocols (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 interactive command because it may have to ask for the "ownertrust" values for keys.
The user has to give an estimation of how far she trusts the owner of the displayed key to
correctly certify (sign) other keys. GnuPG only asks for the ownertrust value if it has not yet
been assigned to a key. Using the --edit-key menu, the assigned value can be changed at any time.
--check-trustdb
Do trust database maintenance without user 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:
gpg2 --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
gpg2 --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.
--tofu-set-policy auto|good|unknown|bad|ask key...
Set the TOFU policy for all the bindings associated with the specified keys. For more information
about the meaning of the policies, see: [trust-model-tofu]. The keys may be specified either by
their fingerprint (preferred) or their keyid.
How to manage your keys
This section explains the main commands for key management
--quick-gen-key user-id
This is a simple command to generate a standard key with one user id. In contrast to --gen-key
the key is generated directly without the need to answer a bunch of prompts. Unless the option
--yes is given, the key creation will be canceled if the given user id already exists in the key
ring.
If invoked directly on the console without any special options an answer to a ``Continue?'' style
confirmation prompt is required. In case the user id already exists in the key ring a second
prompt to force the creation of the key will show up.
If this command is used with --batch, --pinentry-mode has been set to loopback, and one of the
passphrase options (--passphrase, --passphrase-fd, or passphrase-file) is used, the supplied
passphrase is used for the new key and the agent does not ask for it. To create a key without any
protection --passphrase '' may be used.
--gen-key
Generate a new key pair using the current default parameters. This is the standard command to
create a new key. In addition to the key a revocation certificate is created and stored in the
‘openpgp-revocs.d’ directory below the GnuPG home directory.
--full-gen-key
Generate a new key pair with dialogs for all options. This is an extended version of --gen-key.
There is also a feature which allows you to create keys in batch mode. See the manual section
``Unattended key generation'' on how to use this.
--gen-revoke name
Generate a revocation certificate for the complete key. To only revoke a subkey or a key
signature, use the --edit command.
This command merely creates the revocation certificate so that it can be used to revoke the key if
that is ever needed. To actually revoke a key the created revocation certificate needs to be
merged with the key to revoke. This is done by importing the revocation certificate using the
--import command. Then the revoked key needs to be published, which is best done by sending the
key to a keyserver (command --send-key) and by exporting (--export) it to a file which is then
send to frequent communication partners.
--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 or key ID 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 signature), and trust (like the "trust" command). It is generally only
useful in distinct communities or groups.
Note that "l" (for local / non-exportable), "nr" (for non-revocable, and "t" (for trust) may be
freely mixed and prefixed to "sign" to create a signature of any type desired.
If the option --only-sign-text-ids is specified, then any non-text based user ids (e.g., photo IDs) will
not be selected for signing.
delsig Delete a signature. Note that it is not possible to retract a signature, once it has been
send to the public (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. With the extra option selfsig only self-
signatures are shown.
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 primary 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 including 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 gpg2 --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 (secondary 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 This is dummy command which exists only for backward compatibility.
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 subcommand "lsign" from --edit-key.
--quick-sign-key fpr [names]
--quick-lsign-key fpr [names]
Directly sign a key from the passphrase without any further user interaction. The fpr must be the
verified primary fingerprint of a key in the local keyring. If no names are given, all useful user
ids are signed; with given [names] only useful user ids matching one of theses names are signed.
The command --quick-lsign-key marks the signatures as non-exportable. If such a non-exportable
signature already exists the --quick-sign-key turns it into a exportable signature.
This command uses reasonable defaults and thus does not provide the full flexibility of the "sign"
subcommand from --edit-key. Its intended use is to help unattended key signing by utilizing a
list of verified fingerprints.
--quick-adduid user-id new-user-id
This command adds a new user id to an existing key. In contrast to the interactive sub-command
adduid of --edit-key the new-user-id is added verbatim with only leading and trailing white space
removed, it is expected to be UTF-8 encoded, and no checks on its form are applied.
--passwd user_id
Change the passphrase of the secret key belonging to the certificate specified as user_id. This
is a shortcut for the sub-command passwd of the edit key menu.
OPTIONS
gpg2 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 execution of gpg.
Please remember that option parsing stops as soon as a non-option is encountered, you can explicitly stop
parsing by using the special option --.
How to change the configuration
These options are used to change the configuration and are usually found in the option file.
--default-key name
Use name as the default key to sign with. If this option is not used, the default key is the first
key found in the secret keyring. Note that -u or --local-user overrides this option. This option
may be given multiple times. In this case, the last key for which a secret key is available is
used. If there is no secret key available for any of the specified values, GnuPG will not emit an
error message but continue as if this option wasn't given.
--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. Does not work
with --with-colons: see --attribute-fd for the appropriate way to get photo data for
scripts and other frontends.
show-usage
Show usage information for keys and subkeys in the standard key listing. This is a list of
letters indicating the allowed usage for a key (E=encryption, S=signing, C=certification,
A=authentication). Defaults to yes.
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 yes.
show-unusable-uids
Show revoked and expired user IDs in key listings. Defaults to no.
show-unusable-subkeys
Show revoked and expired subkeys in key listings. Defaults to no.
show-keyring
Display the keyring name at the head of key listings to show which keyring a given key
resides on. Defaults to no.
show-sig-expire
Show signature expiration dates (if any) during --list-sigs or --check-sigs listings.
Defaults to no.
show-sig-subpackets
Include signature subpackets in the key listing. This option can take an optional argument
list of the subpackets to list. If no argument is passed, list all subpackets. Defaults to
no. This option is only meaningful 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 yes.
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 yes.
show-uid-validity
Display the calculated validity of the user IDs on the key that issued the signature.
Defaults to yes.
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 meaningful if pka-lookups is set.
--enable-large-rsa
--disable-large-rsa
With --gen-key and --batch, enable the creation of larger RSA secret keys than is generally
recommended (up to 8192 bits). These large keys are more expensive to use, and their signatures
and certifications are also larger.
--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"), "%U" for a base32
encoded hash of the user ID, 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
This is an obsolete option and ignored. All secret keys are stored in the ‘private-keys-v1.d’
directory below the GnuPG home directory.
--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 Windows systems) by means of
the Registry entry HKCU\Software\GNU\GnuPG:HomeDir.
On Windows systems it is possible to install GnuPG as a portable application. In this case only
this command line option is considered, all other ways to set a home directory are ignored.
To install GnuPG as a portable application under Windows, create an empty file name ‘gpgconf.ctl’
in the same directory as the tool ‘gpgconf.exe’. The root of the installation is than that
directory; or, if ‘gpgconf.exe’ has been installed directly below a directory named ‘bin’, its
parent directory. You also need to make sure that the following directories exist and are
writable: ‘ROOT/home’ for the GnuPG home and ‘ROOT/var/cache/gnupg2’ for internal cache files.
--display-charset name
Set the name of the native character set. This is used to convert some informational strings like
user IDs to the proper UTF-8 encoding. Note that this has nothing to do with the character set of
data to be encrypted or signed; GnuPG does not recode user-supplied data. If this option is not
used, the default character set is determined from the current locale. A verbosity level of 3
shows the chosen set. Valid values for name are:
iso-8859-1
This is the Latin 1 set.
iso-8859-2
The Latin 2 set.
iso-8859-15
This is currently an alias for the Latin 1 set.
koi8-r The usual Russian set (rfc1489).
utf-8 Bypass all translations and assume that the OS uses native UTF-8 encoding.
--utf8-strings
--no-utf8-strings
Assume that command line arguments are given as UTF8 strings. The default (--no-utf8-strings) is
to assume that arguments are encoded in the character set as specified by --display-charset. These
options affect all following arguments. Both options may be used multiple times.
--options file
Read options from file and do not try to read them from the default options file in the homedir
(see --homedir). This option is ignored if used in an options file.
--no-options
Shortcut for --options /dev/null. This option is detected before an attempt to open an option
file. Using this option will also prevent the creation of a ‘~/.gnupg’ homedir.
-z n
--compress-level n
--bzip2-compress-level n
Set compression level to n for the ZIP and ZLIB compression algorithms. The default is to use the
default compression level of zlib (normally 6). --bzip2-compress-level sets the compression level
for the BZIP2 compression algorithm (defaulting to 6 as well). This is a different option from
--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 the
key fingerprint and checked the user ID on the key against a photo ID.
3 means you did extensive verification of the key. For example, this could mean that you verified
the key fingerprint with the owner of the key in 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|tofu|tofu+pgp|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 introduced by PGP 2.
tofu
TOFU stands for Trust On First Use. In this trust model, the first time a key is seen, it
is memorized. If later another key is seen with a user id with the same email address, a
warning is displayed indicating that there is a conflict and that the key might be a
forgery and an attempt at a man-in-the-middle attack.
Because a potential attacker is able to control the email address and thereby circumvent
the conflict detection algorithm by using an email address that is similar in appearance to
a trusted email address, whenever a message is verified, statistics about the number of
messages signed with the key are shown. In this way, a user can easily identify attacks
using fake keys for regular correspondents.
When compared with the Web of Trust, TOFU offers significantly weaker security guarantees.
In particular, TOFU only helps ensure consistency (that is, that the binding between a key
and email address doesn't change). A major advantage of TOFU is that it requires little
maintenance to use correctly. To use the web of trust properly, you need to actively sign
keys and mark users as trusted introducers. This is a time-consuming process and anecdotal
evidence suggests that even security-conscious users rarely take the time to do this
thoroughly and instead rely on an ad-hoc TOFU process.
In the TOFU model, policies are associated with bindings between keys and email addresses
(which are extracted from user ids and normalized). There are five policies, which can be
set manually using the --tofu-policy option. The default policy can be set using the
--tofu-default-policy policy.
The TOFU policies are: auto, good, unknown, bad and ask. The auto policy is used by
default (unless overridden by --tofu-default-policy) and marks a binding as marginally
trusted. The good, unknown and bad policies mark a binding as fully trusted, as having
unknown trust or as having trust never, respectively. The unknown policy is useful for
just using TOFU to detect conflicts, but to never assign positive trust to a binding. The
final policy, ask prompts the user to indicate the binding's trust. If batch mode is
enabled (or input is inappropriate in the context), then the user is not prompted and the
undefined trust level is returned.
tofu+pgp
This trust model combines TOFU with the Web of Trust. This is done by computing the trust
level for each model and then taking the maximum trust level where the trust levels are
ordered as follows: unknown < undefined < marginal < fully < ultimate < expired < never.
By setting --tofu-default-policy=unknown, this model can be used to implement the web of
trust with TOFU's conflict detection algorithm, but without its assignment of positive
trust values, which some security-conscious users don't like.
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 valid. 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. Note that this trust model still does not allow the use of
expired, revoked, or disabled keys.
auto Select the trust model depending on whatever the internal trust database says. This is the
default model if such a database already exists.
--auto-key-locate parameters
--no-auto-key-locate
GnuPG can automatically locate and retrieve keys as needed using this option. This happens when
encrypting to an email address (in the "user@example.com" form), and there are no user@example.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.
dane Locate a key using DANE, as specified in draft-ietf-dane-openpgpkey-05.txt.
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.
clear Clear all defined mechanisms. This is useful to override mechanisms given in a config
file.
--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. Note that this option is ignored if the option
--with-colons is used.
--keyserver name
This option is deprecated - please use the --keyserver in ‘dirmngr.conf’ instead.
Use name as your keyserver. This is the server that --recv-keys, --send-keys, and --search-keys
will communicate with to receive keys from, send keys to, and search for keys on. The format of
the name is a URI: `scheme:[//]keyservername[:port]' The scheme is the type of keyserver: "hkp"
for the HTTP (or compatible) keyservers, "ldap" for the LDAP keyservers, or "mailto" for the Graff
email 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=value
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 revocations, and so turning this option off may
result in skipping keys that are incorrectly marked as revoked.
include-disabled
When searching for a key with --search-keys, include keys that are marked on the 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 verified has a preferred keyserver URL, then use that preferred
keyserver to fetch the key from. Note that this option introduces a "web bug": The creator
of the key can see when the keys is refreshed. Thus this option is not enabled by default.
honor-pka-record
If auto-key-retrieve is set, and the signature being verified has a PKA record, then use
the PKA information to fetch the key. Defaults to "yes".
include-subkeys
When receiving a key, include subkeys as potential targets. Note that this option is not
used with HKP keyservers, as they do not support retrieving keys by subkey id.
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 example, when retrieving multiple keys via --recv-keys, the
timeout applies separately to each key retrieval, and not to the --recv-keys command as a
whole. Defaults to 30 seconds.
http-proxy=value
This options is deprecated. Set the proxy to use for HTTP and HKP keyservers. This
overrides any proxy defined in ‘dirmngr.conf’.
verbose
This option has no more function since GnuPG 2.1. Use the dirmngr configuration options
instead.
debug This option has no more function since GnuPG 2.1. Use the dirmngr configuration options
instead.
check-cert
This option has no more function since GnuPG 2.1. Use the dirmngr configuration options
instead.
ca-cert-file
This option has no more function since GnuPG 2.1. Use the dirmngr configuration options
instead.
--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)
--tofu-default-policy auto|good|unknown|bad|ask
The default TOFU policy (defaults to auto). For more information about the meaning of this
option, see: [trust-model-tofu].
--tofu-db-format auto|split|flat
The format for the TOFU DB.
The split file format splits the data across many DBs under the tofu.d directory (one per email
address and one per key). This makes it easier to automatically synchronize the data using a tool
such as Unison (https://www.cis.upenn.edu/~bcpierce/unison/), since the individual files change
rarely.
The flat file format keeps all of the data in the single file tofu.db. This format results in
better performance.
If set to auto (which is the default), GnuPG will first check for the existence of tofu.d and
tofu.db. If one of these exists, the corresponding format is used. If neither or both of these
exist, then GnuPG defaults to the split format. In the latter case, a warning is emitted.
--max-cert-depth n
Maximum depth of a certification chain (default is 5).
--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.
--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
This is dummy option. gpg2 always requires the agent.
--gpg-agent-info
This is dummy option. It has no effect when used with gpg2.
--agent-program file
Specify an agent program to be used for secret key operations. The default value is determined by
running gpgconf with the option --list-dirs. Note that the pipe symbol (|) is used for a
regression test suite hack and may thus not be used in the file name.
--dirmngr-program file
Specify a dirmngr program to be used for keyserver access. The default value is
‘/usr/bin/dirmngr’. This is only used as a fallback when the environment variable DIRMNGR_INFO is
not set or a running dirmngr cannot be connected.
--no-autostart
Do not start the gpg-agent or the dirmngr if it has not yet been started and its service is
required. This option is mostly useful on machines where the connection to gpg-agent has been
redirected to another machines. If dirmngr is required on the remote machine, it may be started
manually using gpgconf --launch dirmngr.
--lock-once
Lock the databases the first time a lock is requested and do not release the lock until the
process terminates.
--lock-multiple
Release the locks every time a lock is no longer needed. Use this to override a previous --lock-
once from a config file.
--lock-never
Disable locking entirely. This option should be used only in very special environments, where it
can be assured that only one process is accessing those files. A bootable floppy with a stand-
alone encryption system will probably use this. Improper usage of this option may lead to data and
key 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 configuration file in case an application does not know about the
smartcard support and waits ad infinitum for an inserted card.
--no-random-seed-file
GnuPG uses a file to store its internal random pool over invocations. This makes random
generation faster; however sometimes write operations are not desired. This option can be used to
achieve that with the cost of slower random generation.
--no-greeting
Suppress the initial copyright message.
--no-secmem-warning
Suppress the warning about "using insecure memory".
--no-permission-warning
Suppress the warning about unsafe file and home directory (--homedir) permissions. Note that the
permission checks that GnuPG performs are not intended to be authoritative, but rather they simply
warn about certain common permission problems. Do not assume that the lack of a warning means that
your system is secure.
Note that the warning for unsafe --homedir 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 gpg2.
--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.
--encrypt-to-default-key
If the default secret key is taken from --default-key, then also encrypt to that key.
--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 decryption. If you want to stop all
further trial decryption you may use close-window button instead of the cancel button.
--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 --hidden-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 recipients 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
something 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 supports 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.
keep-ownertrust
Normally possible still existing ownertrust values of a key are cleared if a key is
imported. This is in general desirable so that a formerly deleted key does not
automatically gain an ownertrust values merely due to import. On the other hand it is
sometimes necessary to re-import a trusted set of keys again but keeping already assigned
ownertrust values. This can be achived by using this option.
repair-pks-subkey-bug
During import, attempt to repair the damage caused by the PKS keyserver bug (pre version
0.9.6) that mangles keys with multiple 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 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" 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-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.
--print-pka-records
Modify the output of the list commands to print PKA records suitable to put into DNS zone files.
An ORIGIN line is printed before each record to allow diverting the records to the corresponding
zone file.
--print-dane-records
Modify the output of the list commands to print OpenPGP DANE records suitable to put into DNS zone
files. An ORIGIN line is printed before each record to allow diverting the records to the
corresponding zone file.
--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. Since GnuPG 2.0.10, this mode is always used and thus this option is
obsolete; it does not harm to use it though.
--legacy-list-mode
Revert to the pre-2.1 public key list mode. This only affects the human readable output and not
the machine interface (i.e. --with-colons). Note that the legacy format does not allow to convey
suitable information for elliptic curves.
--with-fingerprint
Same as the command --fingerprint but changes only the format of the output and may be used
together with another command.
--with-icao-spelling
Print the ICAO spelling of the fingerprint in addition to the hex digits.
--with-keygrip
Include the keygrip in the key listings.
--with-secret
Include info about the presence of a secret key in public key listings done with --with-colons.
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.
--force-v3-sigs
--no-force-v3-sigs
--force-v4-certs
--no-force-v4-certs
These options are obsolete and have no effect since GnuPG 2.1.
--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 gpg2 --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 gpg2 --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).
--personal-compress-preferences string
Set the list of personal compression preferences to string. Use gpg2 --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 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 for symmetric encryption with a passphrase if --personal-cipher-
preferences and --cipher-algo are not given. The default is AES-128.
--s2k-digest-algo name
Use name as the digest algorithm used to mangle the passphrases for symmetric encryption. The
default is SHA-1.
--s2k-mode n
Selects how passphrases for symmetric encryption are mangled. If n is 0 a plain passphrase (which
is in general not recommended) will be used, a 1 adds a salt (which should not be used) to the
passphrase and a 3 (the default) iterates the whole process a number of times (see --s2k-count).
--s2k-count n
Specify how many times the passphrases mangling for symmetric encryption is repeated. This value
may range between 1024 and 65011712 inclusive. The default is inquired from gpg-agent. 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 set to
the default of 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 workarounds for common compatibility problems in different versions of PGP. This is the
default option, so it is not generally needed, but it may be useful to override a different
compliance option in the gpg.conf file.
--openpgp
Reset all packet, cipher and digest options to strict OpenPGP behavior. Use this option to reset
all previous options like --s2k-*, --cipher-algo, --digest-algo and --compress-algo to OpenPGP
compliant values. All PGP workarounds 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.
--pgp6 Set up all options to be as PGP 6 compliant as possible. This restricts you to the ciphers IDEA
(if the IDEA plugin is installed), 3DES, and CAST5, the hashes MD5, SHA1 and RIPEMD160, and the
compression algorithms none and ZIP. This also disables --throw-keyids, and making signatures with
signing subkeys as PGP 6 does not understand signatures made by signing subkeys.
This option implies --disable-mdc --escape-from-lines.
--pgp7 Set up all options to be as PGP 7 compliant as possible. This is identical to --pgp6 except that
MDCs are not disabled, and the list of allowable ciphers is expanded to add AES128, AES192,
AES256, and TWOFISH.
--pgp8 Set up all options to be as PGP 8 compliant as possible. PGP 8 is a lot closer to the OpenPGP
standard than previous versions of PGP, so all this does is disable --throw-keyids and set
--escape-from-lines. All algorithms are allowed except for the SHA224, SHA384, and SHA512
digests.
Doing things one usually doesn't want to do.
-n
--dry-run
Don't make any changes (this is not completely implemented).
--list-only
Changes the behaviour of some commands. This is like --dry-run but different in some cases. The
semantic of this command may be extended in the future. Currently it only skips the actual
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 creation 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) or as a
comma separated list of flag names. To get a list of all supported flags the single word "help"
can be used.
--debug-all
Set all useful debugging flags.
--debug-iolbf
Set stdout into line buffered mode. This option is only honored when given on the command line.
--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 seconds 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 status 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. If given once only the name of the
program and the major number is emitted (default), given twice the minor is also emitted, given
triple the micro is added, and given quad an operating system identification is also emitted.
--no-emit-version disables the version line.
--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 keyname@domain.example.com
(substituting the appropriate keyname and domain name, of course). This is to help prevent
pollution of the IETF reserved notation namespace. The --expert flag overrides the '@' check.
value may be any printable string; it will be encoded in UTF8, so you should check that your
--display-charset is set correctly. If you prefix name with an exclamation mark (!), the notation
data will be flagged as critical (rfc4880:5.2.3.16). --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 (rfc4880:5.2.3.20). If you prefix it with an
exclamation mark (!), the policy URL packet will be flagged as critical. --sig-policy-url sets a
policy url for data signatures. --cert-policy-url sets a policy url for key signatures
(certifications). --set-policy-url sets both.
The same %-expandos used for notation data are available here as well.
--sig-keyserver-url string
Use string as a preferred keyserver URL for data signatures. If you prefix it with an exclamation
mark (!), the keyserver URL packet will be flagged as critical.
The same %-expandos used for notation data are available here as well.
--set-filename string
Use string as the filename which is stored inside messages. This overrides the default, which is
to use the actual filename of the file being encrypted. Using the empty string for string
effectively removes the filename from the output.
--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 algorithms. If this is not used the cipher algorithm is selected from the preferences
stored with the key. In general, you do not want to use this option as it allows you to violate
the OpenPGP standard. --personal-cipher-preferences is the safe way to accomplish the same thing.
--digest-algo name
Use name as the message digest algorithm. Running the program with the command --version yields a
list of supported algorithms. In general, you do not want to use this option as it allows you to
violate the OpenPGP standard. --personal-digest-preferences is the safe way to accomplish the same
thing.
--compress-algo name
Use compression algorithm name. "zlib" is RFC-1950 ZLIB compression. "zip" is RFC-1951 ZIP
compression which is used by PGP. "bzip2" is a more modern compression scheme that can compress
some things better than zip or zlib, but at the cost of more memory used during compression and
decompression. "uncompressed" or "none" disables compression. If this option is not used, the
default behavior is to examine the recipient key preferences to see which algorithms the recipient
supports. If all else fails, ZIP is used for maximum compatibility.
ZLIB may give better compression results than ZIP, as the compression window size is not limited
to 8k. BZIP2 may give even better compression results than that, but will use a significantly
larger amount of memory while compressing and decompressing. This may be significant in low memory
situations. Note, however, that PGP (all versions) only supports ZIP compression. Using any
algorithm other than ZIP or "none" will make the message unreadable with PGP. In general, you do
not want to use this option as it allows you to violate the OpenPGP standard. --personal-compress-
preferences is the safe way to accomplish the same thing.
--cert-digest-algo name
Use name as the message digest algorithm used when signing a key. Running the program with the
command --version yields a list of supported algorithms. Be aware that if you choose an algorithm
that GnuPG supports but other OpenPGP implementations do not, then some users will not be able to
use the key signatures you make, or quite possibly your entire key.
--disable-cipher-algo name
Never allow the use of name as cipher algorithm. The given name will not be checked so that a
later loaded algorithm will still get disabled.
--disable-pubkey-algo name
Never allow the use of name as public key 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 gpg2 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.
Note that this passphrase is only used if the option --batch has also been given. This is
different from GnuPG version 1.x.
--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. Note that this passphrase is only used if the option --batch has also been given. This is
different from GnuPG version 1.x.
--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. Note that this passphrase is only used if the option --batch has also been given. This
is different from GnuPG version 1.x.
--pinentry-mode mode
Set the pinentry mode to mode. Allowed values for mode are:
default
Use the default of the agent, which is ask.
ask Force the use of the Pinentry.
cancel Emulate use of Pinentry's cancel button.
error Return a Pinentry error (``No Pinentry'').
loopback
Redirect Pinentry queries to the caller. Note that in contrast to Pinentry the user is not
prompted again if he enters a bad password.
--command-fd n
This is a replacement for the deprecated shared-memory IPC mode. If this option is enabled, user
input on questions is not expected from the TTY but from the given file descriptor. It should be
used together with --status-fd. See the file doc/DETAILS in the source distribution for details on
how to use it.
--command-file file
Same as --command-fd, except the commands are read out of file file
--allow-non-selfsigned-uid
--no-allow-non-selfsigned-uid
Allow the import and use of keys with user IDs which are not self-signed. This is not recommended,
as a non self-signed user ID is trivial to forge. --no-allow-non-selfsigned-uid disables.
--allow-freeform-uid
Disable all checks on the form of the user ID while generating a new one. This option should only
be used in very special environments as it does not ensure the de-facto standard format of user
IDs.
--ignore-time-conflict
GnuPG normally checks that the timestamps 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
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 protocol anyway) is still okay. This option allows GnuPG to
ignore CRC errors.
--ignore-mdc-error
This option changes a MDC integrity protection failure into a warning. This can be useful if a
message is partially corrupt, but it is necessary to get as much data as possible out of the
corrupt message. However, be aware that a MDC protection failure may also mean that the message
was tampered with intentionally by an attacker.
--allow-weak-digest-algos
Signatures made with known-weak digest algorithms are normally rejected with an ``invalid digest
algorithm'' message. This option allows the verification of signatures made with such weak
algorithms. MD5 is the only digest algorithm considered weak by default. See also --weak-digest
to reject other digest algorithms.
--weak-digest name
Treat the specified digest algorithm as weak. Signatures made over weak digests algorithms are
normally rejected. This option can be supplied multiple times if multiple algorithms should be
considered weak. See also --allow-weak-digest-algos to disable rejection of weak digests. MD5 is
always considered weak, and does not need to be listed explicitly.
--no-default-keyring
Do not add the default keyrings to the list of keyrings. Note that GnuPG will not operate without
any keyrings, so if you use this option and do not provide alternate keyrings via --keyring or
--secret-keyring, then GnuPG will still use the default public or secret keyrings.
--skip-verify
Skip the signature verification step. This may be used to make the decryption faster if the
signature verification is not needed.
--with-key-data
Print key listings delimited by colons (like --with-colons) and print the public key data.
--fast-list-mode
Changes the output of the list commands to work faster; this is achieved by leaving some parts
empty. Some applications don't need the user ID and the trust information given in the listings.
By using this options they can get a faster listing. The exact behaviour of this option may change
in future versions. If you are missing some 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.
You can also use this option if you receive an encrypted message which is abusive or offensive, to
prove to the administrators of the messaging system that the ciphertext transmitted corresponds to
an inappropriate plaintext so they can take action against the offending user.
--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 content of an encrypted message; using this option you can do
this without handing out the secret key.
--ask-sig-expire
--no-ask-sig-expire
When making a data signature, prompt for an 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 followed by the letter d (for days), w (for weeks), m (for months), or y (for
years) (for example "2m" for two months, or "5y" for five years), or an absolute date in the form
YYYY-MM-DD. Defaults to "0".
--ask-cert-expire
--no-ask-cert-expire
When making a key signature, prompt for an 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 distribution for the details of which configuration items may be
listed. --list-config is only usable with --with-colons set.
--list-gcrypt-config
Display various internal configuration parameters of Libgcrypt.
--gpgconf-list
This command is similar to --list-config but in general only internally used by the gpgconf tool.
--gpgconf-test
This is more or less dummy action. However it parses the configuration file and returns with
failure if the configuration file would prevent gpg from startup. Thus it may be used to run a
syntax check on the configuration file.
Deprecated options
--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.
--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 certificate are the low 64 bits of its SHA-1 fingerprint. The use of key Ids is just a
shortcut, for all automated processing the 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. gpg also allows the use of the space separated SHA-1 fingerprint
as printed by the key listing commands.
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 <heinrichh@uni-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.
<heinrichh@uni-duesseldorf.de>
By partial match on an email address.
This is indicated by prefixing the search string with an @. This uses a substring search but
considers only the mail address (i.e. inside the angle brackets).
@heinrichh
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
. and + prefixes
These prefixes are reserved for looking up mails anchored at the end and for a word search mode.
They are not yet implemented and using them is undefined.
Please note that we have reused the hash mark identifier which was used in old GnuPG versions to
indicate the so called local-id. It is not anymore used and there should be no conflict when used
with X.509 stuff.
Using the RFC-2253 format of DNs has the drawback that it is not possible to map them back to the
original encoding, however we don't have to do this because our key database stores this encoding
as meta data.
FILES
There are a few configuration files to control certain aspects of gpg2'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 gpg2 on startup. It may contain any valid long
option; the leading two dashes may not be entered and the option may not be abbreviated. This
default name may be changed on the command line (see: [gpg-option --options]). You should backup
this file.
Note that on larger installations, it is useful to put predefined files into the directory
‘/etc/skel/.gnupg2’ so that newly created users start up with a working configuration. For existing
users a small helper script is provided to create these files (see: [addgnupghome]).
For internal purposes gpg2 creates and maintains a few other files; They all live in in the current home
directory (see: [option --homedir]). Only the gpg2 program may modify these files.
~/.gnupg/pubring.gpg
The public keyring. You should backup this file.
~/.gnupg/pubring.gpg.lock
The lock file for the public keyring.
~/.gnupg/pubring.kbx
The public keyring using a different format. This file is sharred with gpgsm. You should backup
this file.
~/.gnupg/pubring.kbx.lock
The lock file for ‘pubring.kbx’.
~/.gnupg/secring.gpg
A secret keyring as used by GnuPG versions before 2.1. It is not used by GnuPG 2.1 and later.
~/.gnupg/.gpg-v21-migrated
File indicating that a migration to GnuPG 2.1 has been done.
~/.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.
~/.gnupg/secring.gpg.lock
The lock file for the secret keyring.
~/.gnupg/openpgp-revocs.d/
This is the directory where gpg stores pre-generated revocation certificates. The file name
corresponds to the OpenPGP fingerprint of the respective key. It is suggested to backup those
certificates and if the primary private key is not stored on the disk to move them to an external
storage device. Anyone who can access theses files is able to revoke the corresponding key. You
may want to print them out. You should backup all files in this directory and take care to keep
this backup closed away.
/usr/share/gnupg2/options.skel
The skeleton options file.
/usr/lib/x86_64-linux-gnu/gnupg2/
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
This variable was used by GnuPG versions before 2.1
PINENTRY_USER_DATA
This value is passed via gpg-agent to pinentry. It is useful to convey extra information to a
custom pinentry.
COLUMNS
LINES Used to size some displays to the full size of the screen.
LANGUAGE
Apart from its use by GNU, it is used in the W32 version to override the language selection done
through the Registry. If used and set to a 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), gpgsm(1), gpg-agent(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 2.1.11 2016-01-21 GPG2(1)