These options are used to change the configuration and most of them are usually found in the option file.
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.
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.
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.
Reset --default-recipient and --default-recipient-self. Should not be used in an option file.
Give more information during processing. If used twice, the input data is listed in detail.
Reset verbose level to 0. Should not be used in an option file.
Try to be as quiet as possible. Should not be used in an option file.
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.
It is highly recommended to use this option along with the options
--status-fd and --with-colons for any unattended use of
gpg. Should not be used in an option file.
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.
Assume "yes" on most questions. Should not be used in an option file.
Assume "no" on most questions. Should not be used in an option file.
This is a space or comma delimited string that gives options used when listing keys and signatures (that is, --list-keys, --check-signatures, --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:
Causes --list-keys, --check-signatures, --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 information for keys and subkeys in the standard key
listing. This is a list of letters indicating the allowed usage for a
A=authentication). Defaults to yes.
Show policy URLs in the --check-signatures listings. Defaults to no.
Show all, IETF standard, or user-defined signature notations in the --check-signatures listings. Defaults to no.
Show any preferred keyserver URL in the --check-signatures listings. Defaults to no.
Display the calculated validity of user IDs during key listings. Defaults to yes.
Show revoked and expired user IDs in key listings. Defaults to no.
Show revoked and expired subkeys in key listings. Defaults to no.
Display the keyring name at the head of key listings to show which keyring a given key resides on. Defaults to no.
Show signature expiration dates (if any) during --check-signatures listings. Defaults to no.
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 --check-signatures.
For each user-id which has a valid mail address print only the fingerprint followed by the mail address.
With –list-sigs and –check-sigs sort the signatures by keyID and creation time to make it easier to view the history of these signatures. The self-signature is also listed before other signatures. Defaults to yes.
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:
Display any photo IDs present on the key that issued the signature. Defaults to no. See also --photo-viewer.
Show policy URLs in the signature being verified. Defaults to yes.
Show all, IETF standard, or user-defined signature notations in the signature being verified. Defaults to IETF standard.
Show any preferred keyserver URL in the signature being verified. Defaults to yes.
Display the calculated validity of the user IDs on the key that issued the signature. Defaults to yes.
Show revoked and expired user IDs during signature verification. Defaults to no.
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.
With –generate-key and –batch, enable the creation of RSA secret keys as large as 8192 bit. Note: 8192 bit is more than is generally recommended. These large keys don’t significantly improve security, but they are more expensive to use, and their signatures and certifications are larger. This option is only available if the binary was build with large-secmem support.
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.
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.
On Unix the default viewer is
xloadimage -fork -quiet -title 'KeyID 0x%k' STDIN
with a fallback to
display -title 'KeyID 0x%k' %i
and finally to
!ShellExecute 400 %i is used; here the command is a meta
command to use that API call followed by a wait time in milliseconds
which is used to give the viewer time to read the temporary image file
before gpg deletes it again. Note that if your image viewer program
is not secure, then executing it from gpg does not make it secure.
Sets a list of directories to search for photo viewers If not provided
photo viewers use the
PATH environment variable.
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.
If the option --no-keyring has been used no keyrings will be used at all.
This is an obsolete option and ignored. All secret keys are stored in the private-keys-v1.d directory below the GnuPG home directory.
Designate file as the primary public keyring. This means that newly imported keys (via --import or keyserver --recv-from) will go to this keyring.
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).
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
(on Windows systems) by means of the Registry entry
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 named gpgconf.ctl in the same directory as the tool gpgconf.exe. The root of the installation is then 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 ROOTAPPDATA/GNU/cache/gnupg for internal cache files.
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. This option should not be used on Windows. Valid values for name are:
This is the Latin 1 set.
The Latin 2 set.
This is currently an alias for the Latin 1 set.
The usual Russian set (RFC-1489).
Bypass all translations and assume that the OS uses native UTF-8 encoding.
Assume that command line arguments are given as UTF-8 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. This option should not be used in an option file.
This option has no effect on Windows. There the internal used UTF-8 encoding is translated for console input and output. The command line arguments are expected as Unicode and translated to UTF-8. Thus when calling this program from another, make sure to use the Unicode version of CreateProcess.
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.
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.
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.
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.
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.
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.
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).
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 or fingerprint
Assume that the specified key (which must be given as a full 8 byte key ID, a 20 byte, or 32 byte fingerprint) 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.
Set what trust model GnuPG should follow. The models are:
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.
This is the standard Web of Trust as introduced by PGP 2.
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 with a user id with the same email address is seen, both keys are marked as suspect. In that case, the next time either is used, a warning is displayed describing the conflict, why it might have occurred (either the user generated a new key and failed to cross sign the old and new keys, the key is forgery, or a man-in-the-middle attack is being attempted), and the user is prompted to manually confirm the validity of the key in question.
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 option.
The TOFU policies are:
auto policy is used by
default (unless overridden by --tofu-default-policy) and
marks a binding as marginally trusted. The
bad policies mark a binding as fully
trusted, as having unknown trust or as having trust never,
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.
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 <
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.
Key validity is set directly by the user and not calculated via the Web of Trust. This model is solely based on the key and does not distinguish user IDs. Note that when changing to another trust model the trust values assigned to a key are transformed into ownertrust values, which also indicate how you trust the owner of the key to sign other keys.
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.
Select the trust model depending on whatever the internal trust database says. This is the default model if such a database already exists. Note that a tofu trust model is not considered here and must be enabled explicitly.
GnuPG can automatically locate and retrieve keys as needed using this option. This happens when encrypting to an email address (in the "firstname.lastname@example.org" form), and there are no "email@example.com" keys on the local keyring. This option takes any number of the mechanisms listed below, in the order they are to be tried. Instead of listing the mechanisms as comma delimited arguments, the option may also be given several times to add more mechanism. The option --no-auto-key-locate or the mechanism "clear" resets the list. The default is "local,wkd".
Locate a key using DNS CERT, as specified in RFC-4398.
Locate a key using DANE, as specified in draft-ietf-dane-openpgpkey-05.txt.
Locate a key using the Web Key Directory protocol.
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)’.
Locate the key using the Active Directory (Windows only).
Locate a key using a keyserver.
In addition, a keyserver URL as used in the
configuration may be used here to query that particular keyserver.
Locate the key using the local keyrings. This mechanism allows the user to select the order a local key lookup is done. Thus using ‘--auto-key-locate local’ is identical to --no-auto-key-locate.
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
local is also used.
Clear all defined mechanisms. This is useful to override
mechanisms given in a config file. Note that a
mechanisms will also be cleared unless it is given after the
This is an offline mechanism to get a missing key for signature verification and for later encryption to this key. If this option is enabled and a signature includes an embedded key, that key is used to verify the signature and on verification success the key is imported. The default is --no-auto-key-import.
On the sender (signing) site the option --include-key-block needs to be used to put the public part of the signing key as âKey Block subpacketâ into the signature.
These options enable or disable the automatic retrieving of keys from a keyserver when verifying signatures made by keys that are not on the local keyring. The default is --no-auto-key-retrieve.
The order of methods tried to lookup the key is:
1. If the option --auto-key-import is set and the signatures includes an embedded key, that key is used to verify the signature and on verification success that key is imported.
2. If a preferred keyserver is specified in the signature and the option honor-keyserver-url is active (which is not the default), that keyserver is tried. Note that the creator of the signature uses the option --sig-keyserver-url to specify the preferred keyserver for data signatures.
3. If the signature has the Signer’s UID set (e.g. using --sender while creating the signature) a Web Key Directory (WKD) lookup is done. This is the default configuration but can be disabled by removing WKD from the auto-key-locate list or by using the option --disable-signer-uid.
4. If any keyserver is configured and the Issuer Fingerprint is part of the signature (since GnuPG 2.1.16), the configured keyservers are tried.
Note that this option makes a "web bug" like behavior possible. Keyserver or Web Key Directory 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.
Select how to display key IDs. "none" does not show the key ID at all but shows the fingerprint in a separate line. "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.
This option is deprecated - please use the --keyserver in dirmngr.conf instead.
Use name as your keyserver. This is the server that --receive-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"/"hkps" for the HTTP (or compatible) keyservers or "ldap"/"ldaps" for the LDAP keyservers. 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.
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:
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.
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.
This is an obsolete alias for the option auto-key-retrieve. Please do not use it; it will be removed in future versions..
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.
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.
These options have no more function since GnuPG 2.1. Use the
dirmngr configuration options instead.
The default list of options is: "self-sigs-only, import-clean, repair-keys, repair-pks-subkey-bug, export-attributes". However, if the actual used source is an LDAP server "no-self-sigs-only" is assumed unless "self-sigs-only" has been explictly configured.
Number of completely trusted users to introduce a new key signer (defaults to 1).
Number of marginally trusted users to introduce a new key signer (defaults to 3)
The default TOFU policy (defaults to
auto). For more
information about the meaning of this option, see trust-model-tofu.
Maximum depth of a certification chain (default is 5).
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 safe 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.
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.
This is dummy option.
gpg always requires the agent.
This is dummy option. It has no effect when used with
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 (
used for a regression test suite hack and may thus not be used in the
Specify a dirmngr program to be used for keyserver access. The default value is INSTDIR/bin/dirmngr.
Entirely disable the use of the Dirmngr.
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 the databases the first time a lock is requested and do not release the lock until the process terminates.
Release the locks every time a lock is no longer needed. Use this to override a previous --lock-once from a config file.
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.
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.
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.
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.
Suppress the initial copyright message.
Suppress the warning about "using insecure memory".
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.
Refuse to run if GnuPG cannot get secure memory. Defaults to no (i.e. run, but give a warning).
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
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.