gpg

gpg(1)                      General Commands Manual                     gpg(1)



NAME
       gpg — encryption and signing tool

SYNOPSIS
       gpg  [--homedir name]  [--options file]  [options]  command  [args]

DESCRIPTION
       gpg is the main program for the GnuPG system.


       This man page only lists the commands and options available.  For more
       verbose documentation get the GNU Privacy Handbook (GPH) or one of the
       other documents at http://www.gnupg.org/documentation/ .

       Please remember that option parsing stops as soon as a non option is
       encountered, you can explicitly stop option parsing by using the
       special option "--".

COMMANDS
       gpg may be run with no commands, in which case it will perform a
       reasonable action depending on the type of file it is given as input
       (an encrypted message is decrypted, a signature is verified, a file
       containing keys is listed).

       gpg recognizes these commands:

       -s, --sign [file]
                 Make a signature. This command may be combined with --encrypt
                 (for a signed and encrypted message), --symmetric (for a
                 signed and symmetrically encrypted message), or --encrypt and
                 --symmetric together (for a signed message that may be
                 decrypted via a secret key or a passphrase).

       --clearsign [file]
                 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.

       -b, --detach-sign [file]
                 Make a detached signature.

       -e, --encrypt [file]
                 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).

       -c, --symmetric [file]
                 Encrypt with a symmetric cipher using a passphrase.  The
                 default symmetric cipher used is CAST5, but may be chosen
                 with the --cipher-algo option.  This option may be combined
                 with --sign (for a signed and symmetrically encrypted
                 message), --encrypt (for a message that may be decrypted via
                 a secret key or a passphrase), or --sign and --encrypt
                 together (for a signed message that may be decrypted via a
                 secret key or a passphrase).

       --store [file]
                 Store only (make a simple RFC1991 packet).

       -d, --decrypt [file]
                 Decrypt file (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 [[sigfile]  [signed-files]]
                 Assume that sigfile is a signature and verify it without
                 generating any output. With no arguments, the signature
                 packet is read from stdin.  If only a sigfile is given, it
                 may be a complete signature or a detached signature, in which
                 case the signed stuff is expected in a file without the
                 ".sig" or ".asc" extension.  With more than 1 argument, the
                 first should be a detached signature and the remaining files
                 are the signed stuff.  To read the signed stuff from stdin,
                 use - as the second filename.  For security reasons a
                 detached signature cannot read the signed material from stdin
                 without denoting it in the above way.

       --multifile
                 This modifies certain other commands to accept multiple files
                 for processing on the command line or read from stdin with
                 each filename on a separate line.  This allows for many files
                 to be processed at once.  --multifile may currently be used
                 along with --verify, --encrypt, and --decrypt.  Note that
                 `--multifile --verify' may not be used with detached
                 signatures.

       --verify-files [files]
                 Identical to `--multifile --verify'.

       --encrypt-files [files]
                 Identical to `--multifile --encrypt'.

       --decrypt-files [files]
                 Identical to `--multifile --decrypt'.

       --list-keys [names]

       --list-public-keys [names]
                 List all keys from the public keyrings, or just the ones
                 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.

       -K, --list-secret-keys [names]
                 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 [names]
                 Same as --list-keys, but the signatures are listed too.

                 For each signature listed, there are several flags in between
                 the "sig" tag and keyid.  These flags give additional
                 information about each signature.  From left to right, they
                 are the numbers 1-3 for certificate check level (see --ask-
                 cert-level), "L" for a local or non-exportable signature (see
                 --lsign-key), "R" for a nonRevocable signature (see the
                 --edit-key command "nrsign"), "P" for a signature that
                 contains a policy URL (see --cert-policy-url), "N" for a
                 signature that contains a notation (see --cert-notation), "X"
                 for an eXpired signature (see --ask-cert-expire), and the
                 numbers 1-9 or "T" for 10 and above to indicate trust
                 signature levels (see the --edit-key command "tsign").

       --check-sigs [names]
                 Same as --list-sigs, but the signatures are verified.

       --fingerprint [names]
                 List all keys 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.

       --gen-key Generate a new key pair. This command is normally only used
                 interactively.

                 There is an experimental feature which allows you to create
                 keys in batch mode. See the file doc/DETAILS in the source
                 distribution on how to use this.

       --edit-key name
                 Present a menu which enables you to do all key related tasks:

                 sign      Make a signature on key of user name If the key is
                           not yet signed by the default user (or the users
                           given with -u), the program displays the
                           information of the key again, together with its
                           fingerprint and asks whether it should be signed.
                           This question is repeated for all users specified
                           with -u.

                 lsign     Same as "sign" but the signature is marked as non-
                           exportable and will therefore never be used by
                           others.  This may be used to make keys valid only
                           in the local environment.

                 nrsign    Same as "sign" but the signature is marked as non-
                           revocable and can therefore never be revoked.

                 tsign     Make a trust signature.  This is a signature that
                           combines the notions of certification (like a
                           regular signature), and trust (like the "trust"
                           command).  It is generally only useful in distinct
                           communities or groups.

                 Note that "l" (for local / non-exportable), "nr" (for non-
                 revocable, and "t" (for trust) may be freely mixed and
                 prefixed to "sign" to create a signature of any type desired.

                 revsig    Revoke a signature.  For every signature which has
                           been generated by one of the secret keys, GnuPG
                           asks whether a revocation certificate should be
                           generated.

                 trust     Change the owner trust value. This updates the
                           trust-db immediately and no save is required.

                 disable

                 enable    Disable or enable an entire key. A disabled key can
                           not normally be used for encryption.

                 adduid    Create an alternate user id.

                 addphoto  Create a photographic user id.  This will prompt
                           for a JPEG file that will be embedded into the user
                           ID.  Note that a very large JPEG will make for a
                           very large key.  Also note that some programs will
                           display your JPEG unchanged (GnuPG), and some
                           programs will scale it to fit in a dialog box
                           (PGP).

                 deluid    Delete a user id.

                 delsig    Delete a signature.

                 revuid    Revoke a user id.

                 addkey    Add a subkey to this key.

                 addcardkey
                           Generate a key on a card and add it to this key.

                 keytocard Transfer the selected secret key (or the primary
                           key if no key has been selected) to a smartcard.
                           The secret key in the keyring will be replaced by a
                           stub if the key could be stored successfully on the
                           card and you use the save command later.  Only
                           certain key types may be transferred to the card.
                           A sub menu allows you to select on what card to
                           store the key.  Note that it is not possible to get
                           that key back from the card - if the card gets
                           broken your secret key will be lost unless you have
                           a backup somewhere.

                 bkuptocard file
                           Restore the given file to a card. This 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.

                 addrevoker [sensitive]
                           Add a designated revoker.  This takes one optional
                           argument: "sensitive".  If a designated revoker is
                           marked as sensitive, it will not be exported by
                           default (see export-options).

                 revkey    Revoke a subkey.

                 expire    Change the key expiration time.  If a subkey is
                           selected, the expiration time of this subkey will
                           be changed.  With no selection, the key expiration
                           of the primary key is changed.

                 passwd    Change the passphrase of the secret key.

                 primary   Flag the current user id as the primary one,
                           removes the primary user id flag from all other
                           user ids and sets the timestamp of all affected
                           self-signatures one second ahead.  Note that
                           setting a photo user ID as primary makes it primary
                           over other photo user IDs, and setting a regular
                           user ID as primary makes it primary over other
                           regular user IDs.

                 uid n     Toggle selection of user id with index n.  Use 0 to
                           deselect all.

                 key n     Toggle selection of subkey with index n.  Use 0 to
                           deselect all.

                 check     Check all selected user ids.

                 showphoto Display the selected photographic user id.

                 pref      List preferences from the selected user ID.  This
                           shows the actual preferences, without including any
                           implied preferences.

                 showpref  More verbose preferences listing for the selected
                           user ID.  This shows the preferences in effect by
                           including the implied preferences of 3DES (cipher),
                           SHA-1 (digest), and Uncompressed (compression) if
                           they are not already included in the preference
                           list.  In addition, the preferred keyserver and
                           signature notations (if any) are shown.

                 setpref string
                           Set the list of user ID preferences to string for
                           all (or just the selected) user IDs.  Calling
                           setpref with no arguments sets the preference list
                           to the default (either built-in or set via
                           --default-preference-list), and calling setpref
                           with "none" as the argument sets an empty
                           preference list.  Use "gpg --version" to get a list
                           of available algorithms.  Note that while you can
                           change the preferences on an attribute user ID (aka
                           "photo ID"), GnuPG does not select keys via
                           attribute user IDs so these preferences will not be
                           used by GnuPG.

                 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.

                 toggle    Toggle between public and secret key listing.

                 clean     Compact (by removing all signatures except the
                           selfsig) any user ID that is no longer usable (e.g.
                           revoked, or expired).  Then, remove any signatures
                           that are not usable by the trust calculations.
                           Specifically, this removes any signature that does
                           not validate, any signature that is superseded by a
                           later signature, revoked signatures, and signatures
                           issued by keys that are not present on the keyring.

                 minimize  Make the key as small as possible.  This removes
                           all signatures from each user ID except for the
                           most recent self-signature.

                 cross-certify
                           Add cross-certification signatures to signing
                           subkeys that may not currently have them.  Cross-
                           certification signatures protect against a subtle
                           attack against signing subkeys.  See --require-
                           cross-certification.

                 save      Save all changes to the key rings and quit.

                 quit      Quit the program without updating the key rings.

                 The listing shows you the key with its secondary keys and all
                 user ids. Selected keys or user ids are indicated by an
                 asterisk. The trust value is displayed with the primary key:
                 the first is the assigned owner trust and the second is the
                 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.

       --card-edit
                 Present a menu to work with a smartcard.  The subcommand
                 "help" provides an overview on available commands.  For a
                 detailed description, please see the Card HOWTO at
                 http://www.gnupg.org/documentation/howtos.html#GnuPG-
                 cardHOWTO .

       --card-status
                 Show the content of the smart card.

       --change-pin
                 Present a menu to allow changing the PIN of a smartcard.
                 This functionality is also available as the subcommand
                 "passwd" with the --card-edit command.

       --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.

       --delete-key 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-key name
                 Remove key from the secret and public keyring. In batch mode
                 the key must be specified by fingerprint.

       --delete-secret-and-public-key name
                 Same as --delete-key, but if a secret key exists, it will be
                 removed first. In batch mode the key must be specified by
                 fingerprint.

       --gen-revoke name
                 Generate a revocation certificate for the complete key. To
                 revoke a subkey or a signature, use the --edit command.

       --desig-revoke name
                 Generate a designated revocation certificate for a key.  This
                 allows a user (with the permission of the keyholder) to
                 revoke someone else's key.

       --export [names]
                 Either export all keys from all keyrings (default keyrings
                 and those registered via option --keyring), or if at least
                 one name is given, those of the given name. The new keyring
                 is written to stdout or to the file given with option
                 "output".  Use together with --armor to mail those keys.

       --send-keys [names]
                 Same as --export but sends the keys to a keyserver.  Option
                 --keyserver must be used to give the name of this keyserver.
                 Don't send your complete keyring to a keyserver - select only
                 those keys which are new or changed by you.

       --export-secret-keys [names]

       --export-secret-subkeys [names]
                 Same as --export, but exports the secret keys instead.  This
                 is normally not very useful and a security risk.  The second
                 form of the command has the special property to render the
                 secret part of the primary key useless; this is a GNU
                 extension to OpenPGP and other implementations can not be
                 expected to successfully import such a key.

                 See the option --simple-sk-checksum if you want to import
                 such an exported key with an older OpenPGP implementation.

       --import [files]

       --fast-import [files]
                 Import/merge keys. This adds the given keys to the keyring.
                 The fast version is currently just a synonym.

                 There are a few other options which control how this command
                 works.  Most notable here is the --keyserver-options merge-
                 only option which does not insert new keys but does only the
                 merging of new signatures, user-IDs and subkeys.

       --recv-keys key IDs
                 Import the keys with the given key IDs from a keyserver.
                 Option --keyserver must be used to give the name of this
                 keyserver.

       --refresh-keys [key IDs]
                 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 trust DB.

       --import-ownertrust [files]
                 Update the trustdb with the ownertrust values stored in files
                 (or stdin if not given); existing values will be overwritten.

       --rebuild-keydb-caches
                 When updating from version 1.0.6 to 1.0.7 this command should
                 be used to create signature caches in the keyring.  It might
                 be handy in other situations too.

       --print-md algo [files]

       --print-mds [files]
                 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. If count
                 is not given or zero, an endless sequence of random bytes
                 will be emitted.  PLEASE, don't use this command unless you
                 know what you are doing; it may remove precious entropy from
                 the system!

       --gen-prime mode           bits            [qbits]
                 Use the source, Luke :-). The output format is still subject
                 to change.

       --version Print version information along with a list of supported
                 algorithms.

       --warranty
                 Print warranty information.

       -h, --help
                 Print usage information.  This is a really long list even
                 though it doesn't list all options.  For every option,
                 consult this manual.

OPTIONS
       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.

       gpg recognizes these options:

       -a, --armor
                 Create ASCII armored output.

       -o, --output 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".

       --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.

       -u, --local-user name
                 Use name as the key to sign with.  Note that this option
                 overrides --default-key.

       --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.

       -r, --recipient name
                 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.

       -R, --hidden-recipient name
                 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.

       --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.

       --encrypt-to name
                 Same as --recipient but this one is intended for use in the
                 options file and may be used with your own user-id as an
                 "encrypt-to-self".  These keys are only used when there are
                 other recipients given either by use of --recipient or by the
                 asked user id.  No trust checking is performed for these user
                 ids and even disabled keys can be used.

       --hidden-encrypt-to name
                 Same as --hidden-recipient but this one is intended for use
                 in the options file and may be used with your own user-id as
                 a hidden "encrypt-to-self".  These keys are only used when
                 there are other recipients given either by use of --recipient
                 or by the asked user id.  No trust checking is performed for
                 these user ids and even disabled keys can be used.

       --no-encrypt-to
                 Disable the use of all --encrypt-to and --hidden-encrypt-to
                 keys.

       -v, --verbose
                 Give more information during processing. If used twice, the
                 input data is listed in detail.

       -q, --quiet
                 Try to be as quiet as possible.

       -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.

       -t, --textmode

       --no-textmode
                 Treat input files as text and store them in the OpenPGP
                 canonical text form with standard "CRLF" line endings.  This
                 also sets the necessary flags to inform the recipient that
                 the encrypted or signed data is text and may need its line
                 endings converted back to whatever the local system uses.
                 This option is useful when communicating between two
                 platforms that have different line ending conventions (UNIX-
                 like to Mac, Mac to Windows, etc).  --no-textmode disables
                 this option, and is the default.

                 If -t (but not --textmode) is used together with armoring and
                 signing, this enables clearsigned messages.  This kludge is
                 needed for command-line compatibility with command-line
                 versions of PGP; normally you would use --sign or --clearsign
                 to select the type of the signature.

       -n, --dry-run
                 Don't make any changes (this is not completely implemented).

       -i, --interactive
                 Prompt before overwriting any files.

       --batch

       --no-batch
                 Use batch mode.  Never ask, do not allow interactive
                 commands.  --no-batch disables this option.

       --no-tty  Make sure that the TTY (terminal) is never used for any
                 output.  This option is needed in some cases because GnuPG
                 sometimes prints warnings to the TTY if --batch is used.

       --yes     Assume "yes" on most questions.

       --no      Assume "no" on most questions.

       --ask-cert-level

       --no-ask-cert-level
                 When making a key signature, prompt for a certification
                 level.  If this option is not specified, the certification
                 level used is set via --default-cert-level.  See --default-
                 cert-level for information on the specific levels and how
                 they are used. --no-ask-cert-level disables this option.
                 This option defaults to no.

       --default-cert-level n
                 The default to use for the check level when signing a key.

                 0 means you make no particular claim as to how carefully you
                 verified the key.

                 1 means you believe the key is owned by the person who claims
                 to own it but you could not, or did not verify the key at
                 all.  This is useful for a "persona" verification, where you
                 sign the key of a pseudonymous user.

                 2 means you did casual verification of the key.  For example,
                 this could mean that you verified that the key 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|direct|always|auto
                 Set what trust model GnuPG should follow.  The models are:


                 pgp       This is the Web of Trust combined with trust
                           signatures as used in PGP 5.x and later.  This is
                           the default trust model when creating a new trust
                           database.

                 classic   This is the standard Web of Trust as used in PGP
                           2.x and earlier.

                 direct    Key validity is set directly by the user and not
                           calculated via the Web of Trust.

                 always    Skip key validation and assume that used keys are
                           always fully trusted.  You generally won't use this
                           unless you are using some external validation
                           scheme.  This option also suppresses the
                           "[uncertain]" tag printed with signature checks
                           when there is no evidence that the user ID is bound
                           to the key.

                 auto      Select the trust model depending on whatever the
                           internal trust database says. This is the default
                           model if such a database already exists.

       --always-trust
                 Identical to `--trust-model always'.  This option is
                 deprecated.

       --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 arguments, in the order
                 they are to be tried:


                 cert      locate a key using DNS CERT, as specified in
                           2538bis (currently in draft):
                           http://www.josefsson.org/rfc2538bis/

                 pka       locate a key using DNS PKA.

                 ldap      locate a key using the PGP Universal method of
                           checking "ldap://keys.(thedomain)".

                 keyserver locate a key using whatever keyserver is defined
                           using the --keyserver option.

                 (keyserver URL)
                           In addition, a keyserver URL as used in the
                           --keyserver option may be used here to query that
                           particular keyserver.

       --keyid-format short|0xshort|long|0xlong
                 Select how to display key IDs.  "short" is the traditional
                 8-character key ID.  "long" is the more accurate (but less
                 convenient) 16-character key ID.  Add an "0x" to either to
                 include an "0x" at the beginning of the key ID, as in
                 0x99242560.

       --keyserver name [name=value1 value2 value3 ...]
                 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://subkeys.pgp.net" uses round robin DNS to
                 give a different keyserver each time you use it.

       --keyserver-options name=value1 [value2 value3 ...]
                 This is a space or comma delimited string that gives options
                 for the keyserver.  Options can be prepended with a `no-' to
                 give the opposite 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.  Defaults to yes.

                 honor-pka-record
                           If auto-key-retrieve is set, and the signature
                           being verified has a PKA record, then use the PKA
                           information to fetch the key.  Defaults to yes.

                 include-subkeys
                           When receiving a key, include subkeys as potential
                           targets.  Note that this option is not used with
                           HKP keyservers, as they do not support retrieving
                           keys by subkey id.

                 use-temp-files
                           On most Unix-like platforms, GnuPG communicates
                           with the keyserver helper program via pipes, which
                           is the most efficient method.  This option forces
                           GnuPG to use temporary files to communicate.  On
                           some platforms (such as Win32 and RISC OS), this
                           option is always enabled.

                 keep-temp-files
                           If using `use-temp-files', do not delete the temp
                           files after using them.  This option is useful to
                           learn the keyserver communication protocol by
                           reading the temporary files.

                 verbose   Tell the keyserver helper program to be more
                           verbose.  This option can be repeated multiple
                           times to increase the verbosity level.

                 timeout[=value]
                           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]
                           For HTTP-like keyserver schemes that (such as HKP
                           and HTTP itself), try to access the keyserver over
                           a proxy.  If a value is specified, use this as the
                           HTTP proxy.  If no value is specified, the value of
                           the environment variable "http_proxy", if any, will
                           be used.

                 max-cert-size[=value]
                           When retrieving a key via DNS CERT, only accept
                           keys up to this size.  Defaults to 16384 bytes.

       --import-options parameters
                 This is a space or comma delimited string that gives options
                 for importing keys.  Options can be prepended with a `no-' to
                 give the opposite meaning.  The options are:

                 import-local-sigs
                           Allow importing key signatures marked as "local".
                           This is not generally useful unless a shared
                           keyring scheme is being used.  Defaults to no.

                 repair-pks-subkey-bug
                           During import, attempt to repair the damage caused
                           by the PKS keyserver bug (pre version 0.9.6) that
                           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-reset-subkey-passwd
                           When using the "--export-secret-subkeys" command,
                           this option resets the passphrases for all exported
                           subkeys to empty.  This is useful when the exported
                           subkey is to be used on an unattended machine where
                           a passphrase doesn't necessarily make sense.
                           Defaults to no.

                 export-clean
                           Compact (remove all signatures from) user IDs on
                           the key being exported if the user IDs are not
                           usable.  Also, do not export any signatures that
                           are not usable.  This includes signatures that were
                           issued by keys that are not present on the keyring.
                           This option is the same as running the --edit-key
                           command "clean" before export except that the local
                           copy of the key is not modified.  Defaults to no.

                 export-minimal
                           Export the smallest key possible.  This removes all
                           signatures except the most recent self-signature on
                           each user ID.  This option is the same as running
                           the --edit-key command "minimize" before export
                           except that the local copy of the key is not
                           modified.  Defaults to no.

       --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-'
                 to give the opposite meaning.  The options are:

                 show-photos
                           Causes --list-keys, --list-sigs, --list-public-
                           keys, and --list-secret-keys to display any photo
                           IDs attached to the key.  Defaults to no.  See also
                           --photo-viewer.

                 show-policy-urls
                           Show policy URLs in the --list-sigs or --check-sigs
                           listings.  Defaults to no.

                 show-notations

                 show-std-notations

                 show-user-notations
                           Show all, IETF standard, or user-defined signature
                           notations in the --list-sigs or --check-sigs
                           listings.  Defaults to no.

                 show-keyserver-urls
                           Show any preferred keyserver URL in the --list-sigs
                           or --check-sigs listings.  Defaults to no.

                 show-uid-validity
                           Display the calculated validity of user IDs during
                           key listings.  Defaults to no.

                 show-unusable-uids
                           Show revoked and expired user IDs in key listings.
                           Defaults to no.

                 show-unusable-subkeys
                           Show revoked and expired subkeys in key listings.
                           Defaults to no.

                 show-keyring
                           Display the keyring name at the head of key
                           listings to show which keyring a given key resides
                           on.  Defaults to no.

                 show-sig-expire
                           Show signature expiration dates (if any) during
                           --list-sigs or --check-sigs listings.  Defaults to
                           no.

                 show-sig-subpackets
                           Include signature subpackets in the key listing.
                           This option can take an optional argument list of
                           the 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 no.

                 show-notations

                 show-std-notations

                 show-user-notations
                           Show all, IETF standard, or user-defined signature
                           notations in the signature being verified.
                           Defaults to IETF standard.

                 show-keyserver-urls
                           Show any preferred keyserver URL in the signature
                           being verified.  Defaults to no.

                 show-uid-validity
                           Display the calculated validity of the user IDs on
                           the key that issued the signature.  Defaults to no.

                 show-unusable-uids
                           Show revoked and expired user IDs during signature
                           verification.  Defaults to no.

                 pka-lookups
                           Enable PKA lookups to verify sender addresses.
                           Note that PKA is based on DNS, and so enabling this
                           option may disclose information on when and what
                           signatures are verified or to whom data is
                           encrypted.  This is similar to the "web bug"
                           described for the auto-key-retrieve feature.

                 pka-trust-increase
                           Raise the trust in a signature to full if the
                           signature passes PKA validation.  This option is
                           only meaningful if pka-lookups is set.

       --enable-dsa2

       --disable-dsa2
                 Enables new-style DSA keys which (unlike the old style) may
                 be larger than 1024 bit and use hashes other than SHA-1 and
                 RIPEMD/160.  Note that very few programs currently support
                 these keys and signatures from them.

       --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.

       --photo-viewer string
                 This is the command line that should be run to view a photo
                 ID.  "%i" will be expanded to a filename containing the
                 photo.  "%I" does the same, except the file will not be
                 deleted once the viewer exits.  Other flags are "%k" for the
                 key ID, "%K" for the long key ID, "%f" for the key
                 fingerprint, "%t" for the extension of the image type (e.g.
                 "jpg"), "%T" for the MIME type of the image (e.g.
                 "image/jpeg"), and "%%" for an actual percent sign.  If
                 neither %i or %I are present, then the photo will be supplied
                 to the viewer on standard input.

                 The default viewer is "xloadimage -fork -quiet -title 'KeyID
                 0x%k' stdin".  Note that if your image viewer program is not
                 secure, then executing it from GnuPG does not make it secure.

       --exec-path string
                 Sets a list of directories to search for photo viewers and
                 keyserver helpers.  If not provided, keyserver helpers use
                 the compiled-in default directory, and photo viewers use the
                 $PATH environment variable.  Note, that on W32 system this
                 value is ignored when searching for keyserver helpers.

       --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.

       --keyring file
                 Add file to the current list of keyrings.  If file begins
                 with a tilde and a slash, these are replaced by the $HOME
                 directory. If the filename does not contain a slash, it is
                 assumed to be in the GnuPG home directory ("~/.gnupg" if
                 --homedir or $GNUPGHOME is not used).

                 Note that this adds a keyring to the current list.  If the
                 intent is to use the specified keyring alone, use --keyring
                 along with --no-default-keyring.

       --secret-keyring file
                 Same as --keyring but for the secret keyrings.

       --primary-keyring file
                 Designate file as the primary public keyring.  This means
                 that newly imported keys (via --import or keyserver --recv-
                 from) will go to this keyring.

       --trustdb-name file
                 Use file instead of the default trustdb.  If file begins with
                 a tilde and a slash, these are replaced by the $HOME
                 directory. If the filename does not contain a slash, it is
                 assumed to be in the GnuPG home directory ("~/.gnupg" if
                 --homedir or $GNUPGHOME is not used).

       --homedir directory
                 Set the name of the home directory to directory If this
                 option is not used it defaults to "~/.gnupg". It does not
                 make sense to use this in a options file. This also overrides
                 the environment variable $GNUPGHOME.

       --pcsc-driver file
                 Use file to access the smartcard reader.  The current default
                 is `libpcsclite.so.1' for GLIBC based systems,
                 `/System/Library/Frameworks/PCSC.framework/PCSC' for MAC OS
                 X, `winscard.dll' for Windows and `libpcsclite.so' for other
                 systems.

       --ctapi-driver file
                 Use file to access the smartcard reader.  The current default
                 is `libtowitoko.so'.  Note that the use of this interface is
                 deprecated; it may be removed in future releases.

       --disable-ccid
                 Disable the integrated support for CCID compliant readers.
                 This allows to fall back to one of the other drivers even if
                 the internal CCID driver can handle the reader.  Note, that
                 CCID support is only available if libusb was available at
                 build time.

       --reader-port number_or_string
                 This option may be used to specify the port of the card
                 terminal.  A value of 0 refers to the first serial device;
                 add 32768 to access USB devices.  The default is 32768 (first
                 USB device).  PC/SC or CCID readers might need a string here;
                 run the program in verbose mode to get a list of available
                 readers.  The default is then the first reader found.

       --display-charset name
                 Set the name of the native character set.  This is used to
                 convert some informational strings like user IDs to the
                 proper UTF-8 encoding.  Note that this has nothing to do with
                 the character set of data to be encrypted or signed; GnuPG
                 does not recode user supplied data.  If this option is not
                 used, the default character set is determined from the
                 current locale.  A verbosity level of 3 shows the chosen set.
                 Valid values for name are:

                 iso-8859-1
                           This is the Latin 1 set.

                 iso-8859-2
                           The Latin 2 set.

                 iso-8859-15
                           This is currently an alias for the Latin 1 set.

                 koi8-r    The usual Russian set (rfc1489).

                 utf-8     Bypass all translations and assume that the OS uses
                           native UTF-8 encoding.

       --utf8-strings

       --no-utf8-strings
                 Assume that command line arguments are given as UTF8 strings.
                 The default (--no-utf8-strings) is to assume that arguments
                 are encoded in the character set as specified by --display-
                 charset. These options affect all following arguments.  Both
                 options may be used multiple times.

       --options file
                 Read options from file and do not try to read them from the
                 default options file in the homedir (see --homedir). This
                 option is ignored if used in an options file.

       --no-options
                 Shortcut for "--options /dev/null".  This option is detected
                 before an attempt to open an option file.  Using this option
                 will also prevent the creation of a "~./gnupg" homedir.

       --load-extension name
                 Load an extension module. If name does not contain a slash it
                 is searched for in the directory configured when GnuPG was
                 built (generally "/usr/local/lib/gnupg").  Extensions are not
                 generally useful anymore, and the use of this option is
                 deprecated.

       --debug flags
                 Set debugging flags. All flags are or-ed and flags may be
                 given in C syntax (e.g. 0x0042).

       --debug-all
                 Set all useful debugging flags.

       --debug-ccid-driver
                 Enable debug output from the included CCID driver for
                 smartcards.  Note that this option is only available on some
                 system.

       --enable-progress-filter
                 Enable certain PROGRESS status outputs.  This option allows
                 frontends to display a progress indicator while gpg is
                 processing larger files.  There is a slight performance
                 overhead using it.

       --status-fd n
                 Write special status strings to the file descriptor n.  See
                 the file DETAILS in the documentation for a listing of them.

       --status-file file
                 Same as --status-fd, except the status data is written to
                 file file.

       --logger-fd n
                 Write log output to file descriptor n and not to stderr.

       --logger-file file
                 Same as --logger-fd, except the logger data is written to
                 file file.

       --attribute-fd n
                 Write attribute subpackets to the file descriptor n.  This is
                 most useful for use with --status-fd, since the status
                 messages are needed to separate out the various subpackets
                 from the stream delivered to the file descriptor.

       --attribute-file file
                 Same as --attribute-fd, except the attribute data is written
                 to file file.

       --comment string

       --no-comments
                 Use string as a comment string in clear text signatures and
                 ASCII armored messages or keys (see --armor).  The default
                 behavior is not to use a comment string.  --comment may be
                 repeated multiple times to get multiple comment strings.
                 --no-comments removes all comments.  It is a good idea to
                 keep the length of a single comment below 60 characters to
                 avoid problems with mail programs wrapping such lines.  Note
                 that comment lines, like all other header lines, are not
                 protected by the signature.

       --emit-version

       --no-emit-version
                 Force inclusion of the version string in ASCII armored
                 output.  --no-emit-version disables this option.

       --sig-notation name=value

       --cert-notation name=value

       -N, --set-notation name=value
                 Put the name value pair into the signature as notation data.
                 name must consist only of printable characters or spaces, and
                 must contain a '@' character in the form
                 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 (rfc2440:5.2.3.15).  --sig-
                 notation sets a notation for data signatures.  --cert-
                 notation sets a notation for key signatures (certifications).
                 --set-notation sets both.

                 There are special codes that may be used in notation names.
                 "%k" will be expanded into the key ID of the key being
                 signed, "%K" into the long key ID of the key being signed,
                 "%f" into the fingerprint of the key being signed, "%s" into
                 the key ID of the key making the signature, "%S" into the
                 long key ID of the key making the signature, "%g" into the
                 fingerprint of the key making the signature (which might be a
                 subkey), "%p" into the fingerprint of the primary key of the
                 key making the signature, "%c" into the signature count from
                 the OpenPGP smartcard, and "%%" results in a single "%".  %k,
                 %K, and %f are only meaningful when making a key signature
                 (certification), and %c is only meaningful when using the
                 OpenPGP smartcard.

       --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.

       --sig-policy-url string

       --cert-policy-url string

       --set-policy-url string
                 Use string as a Policy URL for signatures (rfc2440:5.2.3.19).
                 If you prefix it with an exclamation mark (!), the policy URL
                 packet will be flagged as critical.  --sig-policy-url sets a
                 policy url for data signatures.  --cert-policy-url sets a
                 policy url for key signatures (certifications).  --set-
                 policy-url sets both.

                 The same %-expandos used for notation data are available here
                 as well.

       --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.

       --sig-keyserver-url string
                 Use string as a preferred keyserver URL for data signatures.
                 If you prefix it with an exclamation mark, the keyserver URL
                 packet will be flagged as critical.

                 The same %-expandos used for notation data are available here
                 as well.

       --set-filename string
                 Use string as the filename which is stored inside messages.
                 This overrides the default, which is to use the actual
                 filename of the file being encrypted.

       --for-your-eyes-only

       --no-for-your-eyes-only
                 Set the `for your eyes only' flag in the message.  This
                 causes GnuPG to refuse to save the file unless the --output
                 option is given, and PGP to use the "secure viewer" with a
                 Tempest-resistant font to display the message.  This option
                 overrides --set-filename.  --no-for-your-eyes-only disables
                 this option.

       --use-embedded-filename

       --no-use-embedded-filename
                 Try to create a file with a name as embedded in the data.
                 This can be a dangerous option as it allows to overwrite
                 files.  Defaults to no.

       --completes-needed n
                 Number of completely trusted users to introduce a new key
                 signer (defaults to 1).

       --marginals-needed n
                 Number of marginally trusted users to introduce a new key
                 signer (defaults to 3)

       --max-cert-depth n
                 Maximum depth of a certification chain (default is 5).

       --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.

       --s2k-cipher-algo name
                 Use name as the cipher algorithm used to protect secret keys.
                 The default cipher is CAST5.  This cipher is also used for
                 conventional encryption if --personal-cipher-preferences and
                 --cipher-algo is not given.

       --s2k-digest-algo name
                 Use name as the digest algorithm used to mangle the
                 passphrases.  The default algorithm is SHA-1.

       --s2k-mode n
                 Selects how passphrases are mangled. If n is 0 a plain
                 passphrase (which is not recommended) will be used, a 1 adds
                 a salt to the passphrase and a 3 (the default) iterates the
                 whole process a couple of times.  Unless --rfc1991 is used,
                 this mode is also used for conventional encryption.

       --simple-sk-checksum
                 Secret keys are integrity protected by using a SHA-1
                 checksum.  This method is part of the upcoming enhanced
                 OpenPGP specification but GnuPG already uses it as a
                 countermeasure against certain attacks.  Old applications
                 don't understand this new format, so this option may be used
                 to switch back to the old behaviour.  Using this option bears
                 a security risk.  Note that using this option only takes
                 effect when the secret key is encrypted - the simplest way to
                 make this happen is to change the passphrase on the key (even
                 changing it to the same value is acceptable).

       --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.

       --no-sig-cache
                 Do not cache the verification status of key signatures.
                 Caching gives a much better performance in key listings.
                 However, if you suspect that your public keyring is not save
                 against write modifications, you can use this option to
                 disable the caching.  It probably does not make sense to
                 disable it because all kind of damage can be done if someone
                 else has write access to your public keyring.

       --no-sig-create-check
                 GnuPG normally verifies each signature right after creation
                 to protect against bugs and hardware malfunctions which could
                 leak out bits from the secret key.  This extra verification
                 needs some time (about 115% for DSA keys), and so this option
                 can be used to disable it.  However, due to the fact that the
                 signature creation needs manual interaction, this performance
                 penalty does not matter in most settings.

       --auto-check-trustdb

       --no-auto-check-trustdb
                 If GnuPG feels that its information about the Web of Trust
                 has to be updated, it automatically runs the --check-trustdb
                 command internally.  This may be a time consuming process.
                 --no-auto-check-trustdb disables this option.

       --throw-keyids

       --no-throw-keyids
                 Do not put the recipient key IDs into encrypted messages.
                 This helps to hide the receivers of the message and is a
                 limited countermeasure against traffic analysis.  On the
                 receiving side, it may slow down the decryption process
                 because all 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-fd n
                 Read the passphrase from file descriptor n.  Only the first
                 line will be read from file descriptor n.  If you use 0 for
                 n, the passphrase will be read from stdin.  This can only be
                 used if only one passphrase is supplied.

       --passphrase-file file
                 Read the passphrase from file file.  Only the first line will
                 be read from file file.  This can only be used if only one
                 passphrase is supplied.  Obviously, a passphrase stored in a
                 file is of questionable security if other users can read this
                 file.  Don't use this option if you can avoid it.

       --passphrase string
                 Use string as the passphrase.  This can only be used if only
                 one passphrase is supplied.  Obviously, this is of very
                 questionable security on a multi-user system.  Don't use this
                 option if you can avoid it.

       --command-fd n
                 This is a replacement for the deprecated shared-memory IPC
                 mode.  If this option is enabled, user input on questions is
                 not expected from the TTY but from the given file descriptor.
                 It should be used together with --status-fd. See the file
                 doc/DETAILS in the source distribution for details on how to
                 use it.

       --command-file file
                 Same as --command-fd, except the commands are read out of
                 file file

       --use-agent

       --no-use-agent
                 Try to use the GnuPG-Agent. Please note that this agent is
                 still under development.  With this option, GnuPG first tries
                 to connect to the agent before it asks for a passphrase.
                 --no-use-agent disables this option.

       --gpg-agent-info
                 Override the value of the environment variable
                 GPG_AGENT_INFO.  This is only used when --use-agent has been
                 given

       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 --rfc1991, --force-
                           v3-sigs, --s2k-*, --cipher-algo, --digest-algo and
                           --compress-algo to OpenPGP compliant values.  All
                           PGP workarounds are disabled.

                 --rfc2440 Reset all packet, cipher and digest options to
                           strict RFC-2440 behavior.  Note that this is
                           currently the same thing as --openpgp.

                 --rfc1991 Try to be more RFC-1991 (PGP 2.x) compliant.

                 --pgp2    Set up all options to be as PGP 2.x compliant as
                           possible, and warn if an action is taken (e.g.
                           encrypting to a non-RSA key) that will create a
                           message that PGP 2.x will not be able to handle.
                           Note that `PGP 2.x' here means `MIT PGP 2.6.2'.
                           There are other versions of PGP 2.x available, but
                           the MIT release is a good common baseline.

                           This option implies `--rfc1991 --disable-mdc --no-
                           force-v4-certs --no-sk-comment --escape-from-lines
                           --force-v3-sigs --no-ask-sig-expire --no-ask-cert-
                           expire --cipher-algo IDEA --digest-algo MD5
                           --compress-algo 1'.  It also disables --textmode
                           when encrypting.

                 --pgp6    Set up all options to be as PGP 6 compliant as
                           possible.  This restricts you to the ciphers IDEA
                           (if the IDEA plugin is installed), 3DES, and CAST5,
                           the hashes MD5, SHA1 and RIPEMD160, and the
                           compression algorithms none and ZIP.  This also
                           disables --throw-keyids, and making signatures with
                           signing subkeys as PGP 6 does not understand
                           signatures made by signing subkeys.

                           This option implies `--disable-mdc --no-sk-comment
                           --escape-from-lines --force-v3-sigs --no-ask-sig-
                           expire'

                 --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.

       --force-v3-sigs

       --no-force-v3-sigs
                 OpenPGP states that an implementation should generate v4
                 signatures but PGP versions 5 through 7 only recognize v4
                 signatures on key material.  This option forces v3 signatures
                 for signatures on data.  Note that this option overrides
                 --ask-sig-expire, as v3 signatures cannot have expiration
                 dates.  --no-force-v3-sigs disables this option.

       --force-v4-certs

       --no-force-v4-certs
                 Always use v4 key signatures even on v3 keys.  This option
                 also changes the default hash algorithm for v3 RSA keys from
                 MD5 to SHA-1.  --no-force-v4-certs disables this option.

       --force-mdc
                 Force the use of encryption with a modification detection
                 code.  This is always used with the newer ciphers (those with
                 a blocksize greater than 64 bits), or if all of the recipient
                 keys indicate MDC support in their feature flags.

       --disable-mdc
                 Disable the use of the modification detection code.  Note
                 that by using this option, the encrypted message becomes
                 vulnerable to a message modification attack.

       --allow-non-selfsigned-uid

       --no-allow-non-selfsigned-uid
                 Allow the import and use of keys with user IDs which are not
                 self-signed.  This is not recommended, as a non self-signed
                 user ID is trivial to forge.  --no-allow-non-selfsigned-uid
                 disables.

       --allow-freeform-uid
                 Disable all checks on the form of the user ID while
                 generating a new one.  This option should only be used in
                 very special environments as it does not ensure the de-facto
                 standard format of user IDs.

       --ignore-time-conflict
                 GnuPG normally checks that the timestamps associated with
                 keys and signatures have plausible values.  However,
                 sometimes a signature seems to be older than the key due to
                 clock problems.  This option makes these checks just a
                 warning.  See also --ignore-valid-from for timestamp issues
                 on subkeys.

       --ignore-valid-from
                 GnuPG normally does not select and use subkeys created in the
                 future.  This option allows the use of such keys and thus
                 exhibits the pre-1.0.7 behaviour.  You should not use this
                 option unless you there is some clock problem.  See also
                 --ignore-time-conflict for timestamp issues with signatures.

       --ignore-crc-error
                 The ASCII armor used by OpenPGP is protected by a CRC
                 checksum against transmission errors.  Occasionally the CRC
                 gets mangled somewhere on the transmission channel but the
                 actual content (which is protected by the OpenPGP 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.

       --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-verbose
                 Reset verbose level to 0.

       --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).

       --no-armor
                 Assume the input data is not in ASCII armored format.

       --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-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.

       --with-key-data
                 Print key listings delimited by colons (like --with-colons)
                 and print the public key data.

       --with-fingerprint
                 Same as the command --fingerprint but changes only the format
                 of the output and may be used together with another command.

       --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.

       --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.

       --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.

       --no-literal
                 This is not for normal use.  Use the source to see for what
                 it might be useful.

       --set-filesize
                 This is not for normal use.  Use the source to see for what
                 it might be useful.

       --show-session-key
                 Display the session key used for one message. See --override-
                 session-key for the counterpart of this option.

                 We think that Key Escrow is a Bad Thing; however the user
                 should have the freedom to decide whether to go to prison or
                 to reveal the content of one specific message without
                 compromising all messages ever encrypted for one secret key.
                 DON'T USE IT UNLESS YOU ARE REALLY FORCED TO DO SO.

       --override-session-key string
                 Don't use the public key but the session key string.  The
                 format of this string is the same as the one printed by
                 --show-session-key.  This option is normally not used but
                 comes handy in case someone forces you to reveal the content
                 of an encrypted message; using this option you can do this
                 without handing out the secret key.

       --require-cross-certification

       --no-require-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.  Currently defaults to --no-
                 require-cross-certification, but will be changed to
                 --require-cross-certification in the future.

       --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.  Note that by default, --force-v3-sigs is set
                 which also disables this option.  If you want signature
                 expiration, you must set --no-force-v3-sigs as well as
                 turning --ask-sig-expire on.

       --default-sig-expire
                 The default expiration time to use for signature expiration.
                 Valid values are "0" for no expiration, a number followed by
                 the letter d (for days), w (for weeks), m (for months), or y
                 (for years) (for example "2m" for two months, or "5y" for
                 five years), or an absolute date in the form YYYY-MM-DD.
                 Defaults to "0".

       --ask-cert-expire

       --no-ask-cert-expire
                 When making a key signature, prompt for an 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".

       --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.

       --allow-secret-key-import
                 This is an obsolete option and is not used anywhere.

       --try-all-secrets
                 Don't look at the key ID as stored in the message but try all
                 secret keys in turn to find the right decryption key. This
                 option forces the behaviour as used by anonymous recipients
                 (created by using --throw-keyids) and might come handy in
                 case where an encrypted message contains a bogus key ID.

       --allow-multisig-verification
                 Allow verification of concatenated signed messages.  This
                 will run a signature verification for each data+signature
                 block.  There are some security issues with this option and
                 thus it is off by default.  Note that versions of GPG prior
                 to version 1.4.3 implicitly allowed this.

       --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.

       --group name=value1 [value2 value3 ...]
                 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.

       --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.

       --personal-cipher-preferences string
                 Set the list of personal cipher preferences to string, this
                 list should be a string similar to the one printed by the
                 command "pref" in the edit menu.  This allows the user to
                 factor in their own preferred algorithms when algorithms are
                 chosen via recipient key preferences.  The most highly ranked
                 cipher in this list is also used for the --symmetric
                 encryption command.

       --personal-digest-preferences string
                 Set the list of personal digest preferences to string, this
                 list should be a string similar to the one printed by the
                 command "pref" in the edit menu.  This allows the user to
                 factor in their own preferred algorithms when algorithms are
                 chosen via recipient key preferences.  The most highly ranked
                 digest algorithm in this list is algo used when signing
                 without encryption (e.g. --clearsign or --sign).  The default
                 value is SHA-1.

       --personal-compress-preferences string
                 Set the list of personal compression preferences to string,
                 this list should be a string similar to the one printed by
                 the command "pref" in the edit menu.  This allows the user to
                 factor in their own preferred algorithms when algorithms are
                 chosen via recipient key preferences.  The most highly ranked
                 algorithm in this list is also used when there are no
                 recipient keys to consider (e.g. --symmetric).

       --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 [names]
                 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.

How to specify a user ID
       There are different ways to specify a user ID to GnuPG; here are some
       examples:




       234567C4

       0F34E556E

       01347A56A

       0xAB123456
                 Here the key ID is given in the usual short form.

       234AABBCC34567C4

       0F323456784E56EAB

       01AB3FED1347A5612

       0x234AABBCC34567C4
                 Here the key ID is given in the long form as used by OpenPGP
                 (you can get the long key ID using the option --with-colons).

       1234343434343434C434343434343434

       123434343434343C3434343434343734349A3434

       0E12343434343434343434EAB3484343434343434

       0xE12343434343434343434EAB3484343434343434
                 The best way to specify a key ID is by using the fingerprint
                 of the key.  This avoids any ambiguities in case that there
                 are duplicated key IDs (which are really rare for the long
                 key IDs).

       =Heinrich Heine <heinrichh@uni-duesseldorf.de>
                 Using an exact to match string.  The equal sign indicates
                 this.

       <heinrichh@uni-duesseldorf.de>
                 Using the email address part which must match exactly. The
                 left angle bracket indicates this email address mode.

       @heinrichh
                 Match within the <email.address> part of a user ID.  The at
                 sign indicates this email address mode.

       Heine

       *Heine    By case insensitive substring matching.  This is the default
                 mode but applications may want to explicitly indicate this by
                 putting the asterisk in front.

       Note that you can append an exclamation mark (!) to key IDs or
       fingerprints.  This flag tells GnuPG to use the specified primary or
       secondary key and not to try and calculate which primary or secondary
       key to use.


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.


EXAMPLES
       gpg -se -r Bob file
                 sign and encrypt for user Bob

       gpg --clearsign file
                 make a clear text signature

       gpg -sb  file
                 make a detached signature

       gpg --list-keys  user_ID
                 show keys

       gpg --fingerprint  user_ID
                 show fingerprint

       gpg --verify  pgpfile

       gpg --verify  sigfile [files]
                 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 [files] 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.

ENVIRONMENT
       HOME      Used to locate the default home directory.

       GNUPGHOME If set directory used instead of "~/.gnupg".

       GPG_AGENT_INFO
                 Used to locate the gpg-agent; only honored when --use-agent
                 is set.  The value consists of 3 colon delimited fields: The
                 first is the path to the Unix Domain Socket, the second the
                 PID of the gpg-agent and the protocol version which should be
                 set to 1.  When starting the gpg-agent as described in its
                 documentation, this variable is set to the correct value.
                 The option --gpg-agent-info can be used to override it.

       COLUMNS

       LINES     Used to size some displays to the full size of the screen.

FILES
       ~/.gnupg/secring.gpg
                 The secret keyring

       ~/.gnupg/secring.gpg.lock
                 and the lock file

       ~/.gnupg/pubring.gpg
                 The public keyring

       ~/.gnupg/pubring.gpg.lock
                 and the lock file

       ~/.gnupg/trustdb.gpg
                 The trust database

       ~/.gnupg/trustdb.gpg.lock
                 and the lock file

       ~/.gnupg/random_seed
                 used to preserve the internal random pool

       ~/.gnupg/gpg.conf
                 Default configuration file

       ~/.gnupg/options
                 Old style configuration file; only used when gpg.conf is not
                 found

       /usr[/local]/share/gnupg/options.skel
                 Skeleton options file

       /usr[/local]/lib/gnupg/
                 Default location for extensions

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 WITH OTHER OPENPGP PROGRAMS
       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.

BUGS
       On many systems this program should be installed as setuid(root). This
       is necessary to lock memory pages.  Locking memory pages prevents the
       operating system from writing memory pages (which may contain
       passphrases or other sensitive material) to disk.  If you get no
       warning message about insecure memory your operating system supports
       locking without being root.  The program drops root privileges as soon
       as locked memory is allocated.



                                                                        gpg(1)