gnupg: GPG Configuration Options

 
 4.2.1 How to change the configuration
 -------------------------------------
 
 These options are used to change the configuration and most of them 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’.  Should
      not be used in an option file.
 
 ‘-v, --verbose’
      Give more information during processing.  If used twice, the input
      data is listed in detail.
 
 ‘--no-verbose’
      Reset verbose level to 0.  Should not be used in an option file.
 
 ‘-q, --quiet’
      Try to be as quiet as possible.  Should not be used in an option
      file.
 
 ‘--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’.
 
      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.
 
 ‘--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.  Should not be used in an option
      file.
 
 ‘--no’
      Assume "no" on most questions.  Should not be used in an option
      file.
 
 ‘--list-filter {select=EXPR}’
      A list filter can be used to output only certain keys during key
      listing commands.  For the available property names, see the
      description of ‘--import-filter’.
 
 ‘--list-options PARAMETERS’
      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:
 
      show-photos
           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
           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 ‘--check-signatures’ listings.
           Defaults to no.
 
      show-notations
      show-std-notations
      show-user-notations
           Show all, IETF standard, or user-defined signature notations
           in the ‘--check-signatures’ listings.  Defaults to no.
 
      show-keyserver-urls
           Show any preferred keyserver URL in the ‘--check-signatures’
           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-unusable-sigs
           Show key signature made using weak or unsupported algorithms.
 
      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
           ‘--check-signatures’ 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 ‘--check-signatures’.
 
      show-only-fpr-mbox
           For each user-id which has a valid mail address print only the
           fingerprint followed by the mail address.
 
      sort-sigs
           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.
 
 ‘--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.
 
 ‘--enable-large-rsa’
 ‘--disable-large-rsa’
      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-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.
 
      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 ‘xdg-open %i’.  On Windows ‘!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.
 
 ‘--exec-path STRING’
      Sets a list of directories to search for photo viewers If not
      provided photo viewers use the ‘PATH’ environment variable.
 
 ‘--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" unless ‘--homedir’ or $GNUPGHOME
      is 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.
 
      Note that if the option ‘use-keyboxd’ is enabled in ‘common.conf’,
      no keyrings are used at all and keys are all maintained by the
      keyboxd process in its own database.
 
 ‘--primary-keyring FILE’
      This is a varian of ‘--keyring’ and designates FILE as the primary
      public keyring.  This means that newly imported keys (via
      ‘--import’ or keyserver ‘--recv-from’) will go to this 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.
 
 ‘--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.
 
 ‘--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.  This option should not be used on
      Windows.  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 (RFC-1489).
 
      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 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.
 
 ‘--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’
 ‘--no-compress’
      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.
 
      Option ‘-z’ sets both.  A value of 0 for N disables compression.  A
      value of -1 forces compression using the default level.  Option
      ‘--no-compress’ is identical to ‘-z0’.
 
      Except for the ‘--store’ command compression is always used unless
      ‘gpg’ detects that the input is already compressed.  To inhibit the
      use of compression use ‘-z0’ or ‘--no-compress’; to force
      compression use ‘-z-1’ or option ‘z’ with another compression level
      than the default as indicated by -1.  Note that this overriding of
      the default deection works only with ‘z’ and not with the long
      variant of this option.
 
 ‘--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 OR FINGERPRINT’
      Assume that the specified key (which should be given as
      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.  If the given
      key is not locally available but an LDAP keyserver is configured
      the missing key is imported from that server.
 
 ‘--add-desig-revoker [sensitive:]FINGERPRINT’
      Add the key specified by FINGERPRINT as a designated revoker to
      newly created keys.  If the fingerprint is prefixed with the
      keyword "sensitive:" that info is normally not exported wit the
      key.  This option may be given several time to add more than one
      designated revoker.  If the keyword "clear" is used instead of a
      fingerprint, all designated options previously encountered are
      discarded.  Designated revokers are marked on the key as
      non-revocable.  Note that a designated revoker specified using a
      parameter file will also be added to the 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 experimental
           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’, ‘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 experimental 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.  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.
 
      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.  Note that a tofu trust model is not
           considered here and must be enabled explicitly.
 
 ‘--always-trust’
      Identical to ‘--trust-model always’.
 
 ‘--assert-signer FPR_OR_FILE’
      This option checks whether at least one valid signature on a file
      has been made with the specified key.  The key is either specified
      as a fingerprint or a file listing fingerprints.  The fingerprint
      must be given or listed in compact format (no colons or spaces in
      between).  This option can be given multiple times and each
      fingerprint is checked against the signing key as well as the
      corresponding primary key.  If FPR_OR_FILE specifies a file, empty
      lines are ignored as well as all lines starting with a hash sign.
      With this option gpg is guaranteed to return with an exit code of 0
      if and only if a signature has been encountered, is valid, and the
      key matches one of the fingerprints given by this option.
 
 ‘--assert-pubkey-algo ALGOLIST’
      During data signature verification this options checks whether the
      used public key algorithm matches the algorithms given by ALGOLIST.
      This option can be given multiple times to concatenate more
      algorithms to the list; the delimiter of the list are either commas
      or spaces.
 
      The algorithm names given in the list may either be verbatim names
      like "ed25519" with an optional leading single equal sign, or being
      prefixed with ">", ">=", "<=", or "<".  That prefix operator is
      applied to the number part of the algorithm name; for example 2048
      in "rsa2048" or 384 in "brainpoolP384r1".  If the the leading
      non-digits in the name matches, the prefix operator is used to
      compare the number part, a trailing suffix is ignored in this case.
      For example an algorithm list ">rsa3000, >=brainpool384r1,
      =ed25519" allows RSA signatures with more that 3000 bits, Brainpool
      curves 384 and 512, and the ed25519 algorithm.
 
      With this option gpg (and also gpgv) is guaranteed to return with
      an exit code of 0 if and only if all valid signatures on data are
      made using a matching algorithm from the given list.
 
 ‘--auto-key-locate MECHANISMS’
 ‘--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
      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".
 
      cert
           Locate a key using DNS CERT, as specified in RFC-4398.
 
      dane
           Locate a key using DANE, as specified in
           draft-ietf-dane-openpgpkey-05.txt.
 
      wkd
           Locate a key using the Web Key Directory protocol.
 
      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)’.
 
      ntds
           Locate the key using the Active Directory (Windows only).
           This method also allows one to search by fingerprint using the
           command ‘--locate-external-key’.  Note that this mechanism is
           actually a shortcut for the mechanism ‘keyserver’ but using
           "ldap:///" as the keyserver.
 
      keyserver
           Locate a key using a keyserver.  This method also allows one
           to search by fingerprint using the command
           ‘--locate-external-key’ if any of the configured keyservers is
           an LDAP server.
 
      keyserver-URL
           In addition, a keyserver URL as used in the ‘dirmngr’
           configuration may be used here to query that particular
           keyserver.  This method also allows one to search by
           fingerprint using the command ‘--locate-external-key’ if the
           URL specifies an LDAP server.
 
      local
           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’.
 
      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.  Note that a ‘nodefault’ in
           MECHANISMS will also be cleared unless it is given after the
           ‘clear’.
 
 ‘--auto-key-import’
 ‘--no-auto-key-import’
      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 “Key Block
      subpacket” into the signature.
 
 ‘--auto-key-retrieve’
 ‘--no-auto-key-retrieve’
      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.
 
 ‘--keyid-format {none|short|0xshort|long|0xlong}’
      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.
 
 ‘--keyserver NAME’
      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.
 
      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 is an obsolete alias for the option ‘auto-key-retrieve’.
           Please do not use it; it will be removed in future versions..
 
      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.
 
      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
      http-proxy=VALUE
      verbose
      debug
      check-cert
      ca-cert-file
           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, 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 explicitly configured.
 
 ‘--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, ⇒trust-model-tofu.
 
 ‘--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 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.
 
 ‘--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.  ‘gpg’ always requires the agent.
 
 ‘--gpg-agent-info’
      This is dummy option.  It has no effect when used with ‘gpg’.
 
 ‘--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’.
 
 ‘--disable-dirmngr’
      Entirely disable the use of the Dirmngr.
 
 ‘--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.
 
 ‘--require-secmem’
 ‘--no-require-secmem’
      Refuse to run if GnuPG cannot get secure memory.  Defaults to no
      (i.e.  run, but give a warning).
 
 ‘--require-cross-certification’
 ‘--no-require-cross-certification’
      When verifying a signature made from a subkey, ensure that the
      cross certification "back signature" on the subkey is present and
      valid.  This protects against a subtle attack against subkeys that
      can sign.  Defaults to ‘--require-cross-certification’ for ‘gpg’.
 
 ‘--expert’
 ‘--no-expert’
      Allow the user to do certain nonsensical or "silly" things like
      signing an expired or revoked key, or certain potentially
      incompatible things like generating unusual key types.  This also
      disables certain warning messages about potentially incompatible
      actions.  As the name implies, this option is for experts only.  If
      you don't fully understand the implications of what it allows you
      to do, leave this off.  ‘--no-expert’ disables this option.