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INFO-DIR-SECTION GnuPG
START-INFO-DIR-ENTRY
* gpg: (gpg).                         GnuPG encryption and signing tool.
END-INFO-DIR-ENTRY


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gpg
***

* Menu:

Name
****

   gpg --- encryption and signing tool</>

Synopsis
********

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/docs.html .

   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' recognizes these commands:

-s, --sign
     Make a signature. This command may be combined with --encrypt.

--clearsign
     Make a clear text signature.

-b, --detach-sign
     Make a detached signature.

-e, --encrypt
     Encrypt data. This option may be combined with --sign.

-c, --symmetric
     Encrypt with a symmetric cipher using a passphrase. The default
     symmetric cipher used is CAST5, but may be chosen with the
     --cipher-algo option.

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

--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.

--verify-files `files'
     This is a special version of the --verify command which does not
     work with detached signatures. The command expects the files to be
     verified either on the command line or reads the filenames from
     stdin; each name must be on separate line. The command is intended
     for quick checking of many files.

--encrypt-files `files'
     This is a special version of the --encrypt command. The command
     expects the files to be encrypted either on the command line or
     reads the filenames from stdin; each name must be on separate
     line. The command is intended for a quick encryption of multiple
     files.

--decrypt-files `files'
     The same as --encrypt-files with the difference that files will be
     decrypted. The syntax or the filenames is the same.

--list-keys `names'
--list-public-keys `names'
     List all keys from the public keyrings, or just the ones given on
     the command line.

--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.

--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.

    nrlsign
          Combines the functionality of nrsign and lsign to make a
          signature that is both non-revocable and non-exportable.

    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.

    deluid
          Delete a user id.

    revuid
          Revoke a user id.

    addkey
          Add a subkey to this key.

    delkey
          Remove a subkey.

    addrevoker
          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.

    setpref `string'
          Set the list of user ID preferences to `string', this should
          be a string similar to the one printed by "pref". Using an
          empty string will set the default preference string, using
          "none" will set the preferences to nil. Use "gpg -v
          --version" to get a list of available algorithms. This
          command just initializes an internal list and does not change
          anything unless another command (such as "updpref") which
          changes the self-signatures is used.

    updpref
          Change the preferences of all user IDs (or just of the
          selected ones to the current list of preferences. The
          timestamp of all affected self-signatures will be advanced by
          one second. 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.

    toggle
          Toggle between public and secret key listing.

    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.

--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.

--nrsign-key `name'
     Signs a public key with your secret key but marks it as
     non-revocable.  This is a shortcut version of the subcommand
     "nrsign" 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
     Generate a revocation certificate for the complete key. To revoke
     a subkey or a signature, use the --edit command.

--desig-revoke
     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-all `names'
     Same as --export, but also exports keys which are not compatible
     with OpenPGP.

--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 --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. Option --keyserver must be used to give
     the name of this keyserver.

--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.

--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'.

--mangle-dos-filenames
--no-mangle-dos-filenames
     The Windows version of GnuPG replaces the extension of an output
     filename to avoid problems with filenames containing more than one
     dot. This is not necessary for newer Windows versions and so
     --no-mangle-dos-filenames can be used to switch this feature off
     and have GnuPG append the new extension. This option has no effect
     on non-Windows platforms.

-u, --local-user `name'
     Use `name' as the user ID to sign.  This option is silently
     ignored for the list commands, so that it can be used in an
     options file.

--default-key `name'
     Use `name' as default user ID for signatures. If this is not used
     the default user ID is the first user ID found in the secret
     keyring.

-r, --recipient `name'

     Encrypt for user id `name'. If this option 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.

--no-encrypt-to
     Disable the use of all --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 `n'
     Set compression level to `n'. A value of 0 for `n' disables
     compression. Default is to use the default compression level of
     zlib (normally 6).

-t, --textmode
--no-textmode
     Use canonical text mode. --no-textmode disables this option. 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.

--default-cert-check-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.

--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 `classic|always'
     Set what trust model GnuPG should follow. The models are:

    classic
          This is the regular web-of-trust as used in PGP and GnuPG.

    always
          Skip key validation and assume that used keys are always fully
          trusted. You won't use this unless you have installed 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.

--always-trust
     Identical to `--trust-model always'

--keyserver `name'
     Use `name' as your keyserver. This is the server that --recv-keys,
     --send-keys, and -search-keys will communicate with to receive keys
     from, send keys to, and search for keys on. The format of the
     `name' is a URI: `scheme:[//]keyservername[:port]' The scheme is
     the type of keyserver: "hkp" for the Horowitz (or compatible)
     keyservers, "ldap" for the NAI LDAP keyserver, or "mailto" for the
     Horowitz email keyserver. Note that your particular installation of
     GnuPG may have other keyserver types available as well. Keyserver
     schemes are case-insensitive.

     Most keyservers synchronize with each other, so there is generally
     no need to send keys to more than one server. Using the command
     "host -l pgp.net | grep wwwkeys" gives you a list of HKP
     keyservers. When using one of the wwwkeys servers, due to load
     balancing using round-robin DNS you may notice that you get a
     different key server each time.

--keyserver-options `parameters'
     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 this
          option is always set when using the NAI HKP keyserver, as
          this keyserver does not differentiate between revoked and
          unrevoked keys.

    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.

    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.

    honor-http-proxy
          For keyserver schemes that use HTTP (such as HKP), try to
          access the keyserver over the proxy set with the environment
          variable "http_proxy".

    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.

--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:

    allow-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.

--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:

    include-non-rfc
          Include non-RFC compliant keys in the export. Defaults to yes.

    include-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.

    include-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.

    include-sensitive-revkeys
          Include designated revoker information that was marked as
          "sensitive". Defaults to no.

--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.
     --no-show-photos disables this option.

--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"

--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.

--show-keyring
     Causes --list-keys, -list-public-keys, and -list-secret-keys to
     display the name of the keyring a given key resides on. This is
     only useful when you're listing a specific key or set of keys. It
     has no effect when listing all keys.

--keyring `file'
     Add `file' to the 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
     home-directory ("~/.gnupg" if --homedir is not used).  The
     filename may be prefixed with a scheme:

     "gnupg-ring:" is the default one.

     It might make sense to use it together with --no-default-keyring.

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

--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".

--charset `name'
     Set the name of the native character set. This is used to convert
     some strings to proper UTF-8 encoding. If this option is not used,
     the default character set is determined from the current locale. A
     verbosity level of 3 shows the used one.  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 the arguments are already given as UTF8 strings. The
     default (--no-utf8-strings) is to assume that arguments are
     encoded in the character set as specified by --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.

--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.

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

--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.

--sk-comments
--no-sk-comments
     Include secret key comment packets when exporting secret keys. This
     is a GnuPG extension to the OpenPGP standard, and is off by
     default.  Please note that this has nothing to do with the
     comments in clear text signatures or armor headers.
     --no-sk-comments disables this option.

--no-comment
     See --sk-comments. This option is deprecated and may be removed
     soon.

--comment `string'
     Use `string' as comment string in clear text signatures.  The
     default is not do write a comment string.

--default-comment
     Force to write the standard comment string in clear text
     signatures. Use this to overwrite a --comment from a config file.
     This option is now obsolete because there is no default comment
     string anymore.

--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, --notation-data `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. 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 --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).
     --notation-data 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" for
     the long key ID of the key being signed, "%f" for the key
     fingerprint of the key being signed, "%s" for the key ID of the
     key making the signature, "%S" for the long key ID of the key
     making the signature, and "%%" results in a single "%". %k, %K,
     and %f are only meaningful when making a key signature
     (certification).

--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.
     --no-show-notation disables this option.

--sig-policy-url `string'
--cert-policy-url `string'
--set-policy-url `string'
     Use `string' as 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 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.
     --no-show-policy-url disables this option.

--set-filename `string'
     Use `string' as the name of file which is stored in messages.

--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
     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.

--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.

--digest-algo `name'
     Use `name' as the message digest algorithm. Running the program
     with the command --version yields a list of supported algorithms.

--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 --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. This digest algorithm is also used
     for conventional encryption if --digest-algo is not given.

--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 will be part of an 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 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).

--compress-algo `n'
     Use compression algorithm `n'. The value 2 is RFC1950 ZLIB
     compression. The value 1 is RFC-1951 ZIP compression which is used
     by PGP. 0 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. Note, however, that ZLIB
     may give better compression results if that is more important, as
     the compression window size is not limited to 8k.

--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-keyid
     Do not put the keyid into encrypted packets. This option hides the
     receiver of the message and is a countermeasure against traffic
     analysis. It may slow down the decryption process because all
     available secret keys are tried.

--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'. If you use 0 for
     `n', the passphrase will be read from stdin. This can only be used
     if only one passphrase is supplied.  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.

--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

--rfc1991
     Try to be more RFC1991 (PGP 2.x) compliant.

--pgp2
--no-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 -no-openpgp -disable-mdc
     --no-force-v4-certs -no-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. --no-pgp2 disables this option.

--pgp6
--no-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-keyid, and making signatures with signing subkeys as PGP 6
     does not understand signatures made by signing subkeys.

     This option implies `--disable-mdc -no-comment -escape-from-lines
     --force-v3-sigs -no-ask-sig-expire -compress-algo 1' -no-pgp6
     disables this option.

--pgp7
--no-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. --no-pgp7 disables this option.

--pgp8
--no-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-keyid and set
     -escape-from-lines and --compress-algo 1. The allowed algorithms
     list is the same as -pgp7 with the addition of the SHA-256 digest
     algorithm. --no-pgp8 disables this option.

--openpgp
     Reset all packet, cipher and digest options to 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
     and --pgpX modes are also disabled.

--force-v3-sigs
--no-force-v3-sigs
     OpenPGP states that an implementation should generate v4 signatures
     but PGP versions 5 and higher 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.

--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.

--ignore-crc-error
     The ASCII armor used by OpenPGP is protected by a CRC checksum
     against transmission errors. Sometimes it happens that 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 will let gpg 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.

--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 permissions. Note that the
     file permission checks that GnuPG performs are not intended to be
     authoritative, rather they simply warn about certain common
     permission problems. Do not assume that the lack of a warning
     means that your system is secure.

--no-mdc-warning
     Suppress the warning about missing MDC integrity protection.

--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.

--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 --charset setting.

--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.

--emulate-md-encode-bug
     GnuPG versions prior to 1.0.2 had a bug in the way a signature was
     encoded.  This options enables a workaround by checking faulty
     signatures again with the encoding used in old versions. This may
     only happen for ElGamal signatures which are not widely used.

--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.

--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 is "never".
     --no-ask-sig-expire disables this option.

--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 is "never".
     --no-ask-cert-expire disables this option.

--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 deprecated 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.

--merge-only
     Don't insert new keys into the keyrings while doing an import.

--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-keyid) and might come handy in case where an
     encrypted message contains a bogus key ID.

--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.

     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.

--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.

--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.

--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.

--default-preference-list `string'
     Set the list of default preferences to `string', this list should
     be a string similar to the one printed by the command "pref" in the
     edit menu. This affects both key generation and "updpref" in the
     edit menu.

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.

+Heinrich Heine duesseldorf
     All words must match exactly (not case sensitive) but can appear in
     any order in the user ID. Words are any sequences of letters,
     digits, the underscore and all characters with bit 7 set.

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 exactly the given primary or
secondary key and not to try to figure out which secondary or primary
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 of 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.

http_proxy
     Only honored when the keyserver-option honor-http-proxy is set.

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 be giving both filenames on the command
line or using `-' 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 RIPEMD/160 hash, and the ZLIB 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.

   For example, as of this writing, no version of official PGP supports
the BLOWFISH cipher algorithm. If you use it, no PGP user will be able
to decrypt your message. The same thing applies to the ZLIB compression
algorithm. By default, GnuPG uses the 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 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 --pgp2, -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 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.



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