--version Print the program version and licensing information. Note that you cannot abbreviate this command.
-h Print a usage message summarizing the most useful command line options. Note that you cannot abbreviate this command.
--warranty Print warranty information.
--dump-options Print a list of all available options and commands. Note that you cannot abbreviate this command.
Commands to select the type of operation
-s Make a signature. This command may be combined with --encrypt (for a signed and encrypted message), --symmetric (for a signed and symmetrically encrypted message), or --encrypt and --symmetric together (for a signed message that may be decrypted via a secret key or a passphrase). The key to be used for signing is chosen by default or can be set with the --local-user and --default-key options.
--clearsign Make a clear text signature. The content in a clear text signature is readable without any special software. OpenPGP software is only needed to verify the signature. Clear text signatures may modify end-of-line whitespace for platform independence and are not intended to be reversible. The key to be used for signing is chosen by default or can be set with the --local-user and --default-key options.
-b Make a detached signature.
-e Encrypt data. This option may be combined with --sign (for a signed and encrypted message), --symmetric (for a message that may be decrypted via a secret key or a passphrase), or --sign and --symmetric together (for a signed message that may be decrypted via a secret key or a passphrase).
-c 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 Store only (make a simple RFC1991 literal data packet).
-d Decrypt the file given on the command line (or STDIN if no file is specified) and write it to STDOUT (or the file specified with --output). If the decrypted file is signed, the signature is also verified. This command differs from the default operation, as it never writes to the filename which is included in the file and it rejects files which don't begin with an encrypted message.
--verify Assume that the first argument is a signed file or a detached 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 Identical to --multifile --verify.
--encrypt-files Identical to --multifile --encrypt.
--decrypt-files Identical to --multifile --decrypt.
--list-public-keys List all keys from the public keyrings, or just the keys given on the command line. -k is slightly different from --list-keys in that it allows only for one argument and takes the second argument as the keyring to search. This is for command line compatibility with PGP 2 and has been removed in gpg2.
Avoid using the output of this command in scripts or other programs as it is likely to change as GnuPG changes. See --withcolons for a machine-parseable key listing command that is appropriate for use in scripts and other programs.
-K List all keys from the secret keyrings, or just the ones given on the command line. A # after the letters sec means that the secret key is not usable (for example, if it was created via --export-secret-subkeys).
--list-sigs Same as --list-keys, but the signatures are listed too.
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-certexpire), and the numbers 1-9 or "T" for 10 and above to indicate trust signature levels (see the --edit-key command "tsign").
--check-sigs Same as --list-sigs, but the signatures are verified. Note that for performance reasons the revocation status of a signing key is not shown.
The status of the verification is indicated by a flag directly following the "sig" tag (and thus before the flags described above for --list-sigs). A "!" indicates that the signature has been successfully verified, a "-" denotes a bad signature and a "%" is used if an error occurred while checking the signature (e.g. a non supported algorithm).
--fingerprint List all keys (or the specified ones) along with their fingerprints. This is the same output as --list-keys but with the additional output of a line with the fingerprint. May also be combined with --list-sigs or --check-sigs. If this command is given twice, the fingerprints of all secondary keys are listed too.
--list-packets List only the sequence of packets. This is mainly useful for debugging.
--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.
--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 keyring. In batch mode the key must be specified by fingerprint.
--delete-secret-and-public-key name Same as --delete-key, but if a secret key exists, it will be removed first. In batch mode the key must be specified by fingerprint.
--export Either export all keys from all keyrings (default keyrings and those registered via option --keyring), or if at least one name is given, those of the given name. The new keyring is written to STDOUT or to the file given with option --output. Use together with --armor to mail those keys.
--send-keys key IDs Similar to --export but sends the keys to a keyserver. Fingerprints may be used instead of key IDs. Option --keyserver must be used to give the name of this keyserver. Don't send your complete keyring to a keyserver --select only those keys which are new or changed by you. If no key IDs are given, gpg does nothing.
--export-secret-subkeys 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-check sum if you want to import such an exported key with an older OpenPGP implementation.
--fast-import Import/merge keys. This adds the given keys to the keyring. The fast version is currently just a synonym.
There are a few other options which control how this command works. Most notable here is the --import-options merge-only option which does not insert new keys but does only the merging of new signatures, user-IDs and subkeys.
--recv-keys key IDs Import the keys with the given key IDs from a keyserver. Option --keyserver must be used to give the name of this keyserver.
--refresh-keys Request updates from a keyserver for keys that already exist on the local keyring. This is useful for updating a key with the latest signatures, user IDs, etc. Calling this with no arguments will refresh the entire keyring. Option --keyserver must be used to give the name of the keyserver for all keys that do not have preferred keyservers set (see --keyserver-options honor-key server-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 meth ods 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 --updatetrustdb 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 recreated from a corrupted trustdb. Example: gpg --export-ownertrust > otrust.txt
--import-ownertrust Update the trustdb with the ownertrust values stored in files (or STDIN if not given); existing values will be overwritten. In case of a severely damaged trustdb and if you have a recent backup of the ownertrust values (e.g. in the file 'otrust.txt', you may re-create the trustdb using these commands: cd ~/.gnupg rm trustdb.gpg gpg --import-ownertrust < otrust.txt
--rebuild-keydb-caches When updating from version 1.0.6 to 1.0.7 this command should be used to create signature caches in the keyring. It might be handy in other situations too.
--print-mds Print message digest of algorithm ALGO for all given files or STDIN. With the second form (or a deprecated "*" as algo) digests for all available algorithms are printed.
--gen-random 0|1|2 count Emit count random bytes of the given quality level 0, 1 or 2. If count is not given or zero, an endless sequence of random bytes will be emitted. If used with --armor the output will be base64 encoded. PLEASE, don't use this command unless you know what you are doing; it may remove precious entropy from the system!
--gen-prime mode bits Use the source, Luke :-). The output format is still subject to change.
--dearmor Pack or unpack an arbitrary input into/from an OpenPGP ASCII armor. This is a GnuPG extension to OpenPGP and in general not very useful.
How to manage your keys
This section explains the main commands for key management
--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.
--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.
--edit-key Present a menu which enables you to do most of the key management related tasks. It expects the specification of a key on the command line.
uid n Toggle selection of user ID or photographic user ID with index n. Use * to select all and 0 to deselect all.
key n Toggle selection of subkey with index n. Use * to select all and 0 to deselect all.
sign Make a signature on key of user name If the key is not yet signed by the default user (or the users given with -u), the program displays the information of the key again, together with its fingerprint and asks whether it should be signed. This question is repeated for all users specified with -u.
lsign Same as "sign" but the signature is marked as non-exportable and will therefore never be used by others. This may be used to make keys valid only in the local environment.
nrsign Same as "sign" but the signature is marked as non-revocable and can therefore never be revoked.
tsign Make a trust signature. This is a signature that combines the notions of certification (like a regular signature), and trust (like the "trust" command). It is generally only useful in distinct communities or groups.
Note that "l" (for local / non-exportable), "nr" (for non-revocable, and "t" (for trust) may be freely mixed and prefixed to "sign" to create a signature of any type desired.
delsig Delete a signature. Note that it is not possible to retract a signature, once it has been send to the public (i.e. to a keyserver). In that case you better use revsig.
revsig Revoke a signature. For every signature which has been generated by one of the secret keys, GnuPG asks whether a revocation certificate should be generated.
check Check the signatures on all selected user IDs.
adduid Create an additional user ID.
addphoto Create a photographic user ID. This will prompt for a JPEG file that will be embedded into the user ID. Note that a very large JPEG will make for a very large key. Also note that some programs will display your JPEG unchanged (GnuPG), and some programs will scale it to fit in a dialog box (PGP).
showphoto Display the selected photographic user ID.
deluid Delete a user ID or photographic user ID. Note that it is not possible to retract a user id, once it has been send to the public (i.e. to a keyserver). In that case you better use revuid.
revuid Revoke a user ID or photographic user ID.
primary Flag the current user id as the primary one, removes the primary user id flag from all other user ids and sets the timestamp of all affected self-signatures one second ahead. Note that setting a photo user ID as primary makes it primary over other photo user IDs, and setting a regular user ID as primary makes it primary over other regular user IDs.
keyserver Set a preferred keyserver for the specified user ID(s). This allows other users to know where you prefer they get your key from. See --keyserver-options honor-keyserverurl for more on how this works. Setting a value of "none" removes an existing preferred keyserver.
notation Set a name=value notation for the specified user ID(s). See --cert-notation for more on how this works. Setting a value of "none" removes all notations, setting a notation prefixed with a minus sign (-) removes that notation, and setting a notation name (without the =value) prefixed with a minus sign removes all notations with that name.
pref List preferences from the selected user ID. This shows the actual preferences, without including any implied preferences.
showpref More verbose preferences listing for the selected user ID. This shows the preferences in effect by including the implied preferences of 3DES (cipher), SHA-1 (digest), and Uncompressed (compression) if they are not already included in the preference list. In addition, the preferred keyserver and signature notations (if any) are shown.
setpref string Set the list of user ID preferences to string for all (or just the selected) user IDs. Calling setpref with no arguments sets the preference list to the default (either built-in or set via --default-preference-list), and calling setpref with "none" as the argument sets an empty preference list. Use 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.
When setting preferences, you should list the algorithms in the order which you'd like to see them used by someone else when encrypting a message to your key. If you don't include 3DES, it will be automatically added at the end. Note that there are many factors that go into choosing an algorithm (for example, your key may not be the only recipient), and so the remote OpenPGP application being used to send to you may or may not follow your exact chosen order for a given message. It will, however, only choose an algorithm that is present on the preference list of every recipient key. See also the INTEROPERABILITY WITH OTHER OPENPGP PROGRAMS section below.
addkey Add a subkey to this key.
addcardkey Generate a subkey on a card and add it to this key.
keytocard Transfer the selected secret subkey (or the primary key if no subkey has been selected) to a smartcard. The secret key in the keyring will be replaced by a stub if the key could be stored successfully on the card and you use the save command later. Only certain key types may be transferred to the card. A sub menu allows you to select on what card to store the key. Note that it is not possible to get that key back from the card - if the card gets broken your secret key will be lost unless you have a backup somewhere.
bkuptocard file Restore the given file to a card. This command may be used to restore a backup key (as generated during card initialization) to a new card. In almost all cases this will be the encryption key. You should use this command only with the corresponding public key and make sure that the file given as argument is indeed the backup to restore. You should then select 2 to restore as encryption key. You will first be asked to enter the passphrase of the backup key and then for the Admin PIN of the card.
delkey Remove a subkey (secondart key). Note that it is not possible to retract a subkey, once it has been send to the public (i.e. to a keyserver). In that case you better use revkey.
revkey Revoke a subkey.
expire Change the key or subkey expiration time. If a subkey is selected, the expiration time of this subkey will be changed. With no selection, the key expiration of the primary key is changed.
trust Change the owner trust value for the key. This updates the trust-db immediately and no save is required.
enable Disable or enable an entire key. A disabled key can not normally be used for encryption.
addrevoker Add a designated revoker to the key. This takes one optional argument: "sensitive". If a designated revoker is marked as sensitive, it will not be exported by default (see export-options).
passwd Change the passphrase of the secret key.
toggle 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. All new keys generated have this signature by default, so this option is only useful to bring older keys up to date.
save Save all changes to the key rings and quit.
quit Quit the program without updating the key rings.
The listing shows you the key with its secondary keys and all user ids. The primary user id is indicated by a dot, and selected keys or user ids are indicated by an asterisk. The trust value is displayed with the primary key: the first is the assigned owner trust and the second is the calculated trust value. Letters are used for the values:
- No ownertrust assigned / not yet calculated.
e Trust calculation has failed; probably due to an expired key.
q Not enough information for calculation.
n Never trust this key.
m Marginally trusted.
f Fully trusted.
u Ultimately trusted.
--sign-key name Signs a public key with your secret key. This is a shortcut version of the subcommand "sign" from --edit.
--lsign-key name Signs a public key with your secret key but marks it as non- exportable. This is a shortcut version of the subcommand "lsign" from --edit-key.
--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.
--default-recipient name Use name as default recipient if option --recipient is not used and don't ask if this is a valid one. name must be non-empty.
--default-recipient-self Use the default key as default recipient if option --recipient is not used and don't ask if this is a valid one. The default key is the first one from the secret keyring or the one set with --default-key.
--no-default-recipient Reset --default-recipient and --default-recipient-self.
-v, --verbose Give more information during processing. If used twice, the input data is listed in detail.
--no-verbose Reset verbose level to 0.
-q, --quiet Try to be as quiet as possible.
--no-batch Use batch mode. Never ask, do not allow interactive commands. --no-batch disables this option. Note that even with a filename given on the command line, gpg might still need to read from STDIN (in particular if gpg figures that the input is a detached signature and no data file has been specified). Thus if you do not want to feed data via STDIN, you should connect STDIN to '/dev/null'.
--no-tty Make sure that the TTY (terminal) is never used for any output. This option is needed in some cases because GnuPG sometimes prints warnings to the TTY even if --batch is used.
--yes Assume "yes" on most questions.
--no Assume "no" on most questions.
--list-options parameters This is a space or comma delimited string that gives options used when listing keys and signatures (that is, --list-keys, --list-sigs, --list-public-keys, --list-secret-keys, and the --edit-key functions). Options can be prepended with a no- (after the two dashes) to give the opposite meaning. The options are:
show-photos Causes --list-keys, --list-sigs, --list-public-keys, and --list-secret-keys to display any photo IDs attached to the key. Defaults to no. See also --photo-viewer. Does not work with --with-colons: see --attribute-fd for the appropriate way to get photo data for scripts and other frontends.
show-policy-urls Show policy URLs in the --list-sigs or --check-sigs listings. Defaults to no.
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-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.
show-primary-uid-only Show only the primary user ID during signature verification. That is all the AKA lines as well as photo Ids are not shown with the signature verification status.
pka-lookups Enable PKA lookups to verify sender addresses. Note that PKA is based on DNS, and so enabling this option may disclose information on when and what signatures are verified or to whom data is encrypted. This is similar to the "web bug" described for the auto-key-retrieve feature.
pka-trust-increase Raise the trust in a signature to full if the signature passes PKA validation. This option is only meaningful if pka-lookups is set.
--disable-dsa2 Enable hash truncation for all DSA keys even for old DSA Keys up to 1024 bit. This is also the default with --openpgp. Note that older versions of GnuPG also required this flag to allow the generation of DSA larger than 1024 bit.
--photo-viewer string This is the command line that should be run to view a photo ID. "%i" will be expanded to a filename containing the photo. "%I" does the same, except the file will not be deleted once the viewer exits. Other flags are "%k" for the key ID, "%K" for the long key ID, "%f" for the key fingerprint, "%t" for the exten- sion of the image type (e.g. "jpg"), "%T" for the MIME type of the image (e.g. "image/jpeg"), "%v" for the single-character calculated validity of the image being viewed (e.g. "f"), "%V" for the calculated validity as a string (e.g. "full"), 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 key- server helpers. If not provided, keyserver helpers use the com- piled-in default directory, and photo viewers use the $PATH environment variable. Note, that on W32 system this value is ignored when searching for keyserver helpers.
--keyring file Add file to the current list of keyrings. If file begins with a tilde and a slash, these are replaced by the $HOME directory. If the filename does not contain a slash, it is assumed to be in the GnuPG home directory ("~/.gnupg" if --homedir or $GNUPGHOME is not used).
Note that this adds a keyring to the current list. If the intent is to use the specified keyring alone, use --keyring along with --no-default-keyring.
--secret-keyring file 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 dir Set the name of the home directory to dir. If this option is not used, the home directory defaults to '~/.gnupg'. It is only recognized when given on the command line. It also overrides any home directory stated through the environment variable 'GNUPGHOME' or (on W32 systems) by means of the Registry entry HKCU\Software\GNU\GnuPG:HomeDir.
--pcsc-driver file Use file to access the smartcard reader. The current default is `libpcsclite.so.1' for GLIBC based systems, `/Sys- tem/Library/Frameworks/PCSC.framework/PCSC' for MAC OS X, `win- scard.dll' for Windows and `libpcsclite.so' for other systems.
--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 sup- port 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 termi- nal. 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 con- vert some informational strings like user IDs to the proper UTF-8 encoding. Note that this has nothing to do with the char- acter 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.
--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.
--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 compres- sion 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.
--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.
--no-ask-cert-level When making a key signature, prompt for a certification level. If this option is not specified, the certification level used is set via --default-cert-level. See --default-cert-level for information on the specific levels and how they are used. --no- ask-cert-level disables this option. This option defaults to no.
--default-cert-level n The default to use for the check level when signing a key.
0 means you make no particular claim as to how carefully you verified the key.
1 means you believe the key is owned by the person who claims to own it but you could not, or did not verify the key at all. This is useful for a "persona" verification, where you sign the key of a pseudonymous user.
2 means you did casual verification of the key. For example, this could mean that you verified the key fingerprint and checked the user ID on the key against a photo ID.
3 means you did extensive verification of the key. For example, this could mean that you verified the key fingerprint with the owner of the key in person, and that you checked, by means of a hard to forge document with a photo ID (such as a passport) that the name of the key owner matches the name in the user ID on the key, and finally that you verified (by exchange of email) that the email address on the key belongs to the key owner.
Note that the examples given above for levels 2 and 3 are just that: examples. In the end, it is up to you to decide just what "casual" and "extensive" mean to you.
This option defaults to 0 (no particular claim).
--min-cert-level When building the trust database, treat any signatures with a certification level below this as invalid. Defaults to 2, which disregards level 1 signatures. Note that level 0 "no particular claim" signatures are always accepted.
--trusted-key long key ID Assume that the specified key (which must be given as a full 8 byte key ID) is as trustworthy as one of your own secret keys. This option is useful if you don't want to keep your secret keys (or one of them) online but still want to be able to check the validity of a given recipient's or signator's key.
--trust-model pgp|classic|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.
--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 "firstname.lastname@example.org" form), and there are no user@exam- ple.com keys on the local keyring. This option takes any number of the following mechanisms, in the order they are to be tried:
cert Locate a key using DNS CERT, as specified in rfc4398.
pka Locate a key using DNS PKA.
ldap Using DNS Service Discovery, check the domain in question for any LDAP keyservers to use. If this fails, attempt to locate the key using the PGP Universal method of checking 'ldap://keys.(thedomain)'.
keyserver Locate a key using whatever keyserver is defined using the --keyserver option.
keyserver-URL In addition, a keyserver URL as used in the --keyserver option may be used here to query that particular keyserver.
local Locate the key using the local keyrings. This mechanism allows to select the order a local key lookup is done. Thus using '--auto-key-locate local' is identical to --no-auto-key-locate.
nodefault This flag disables the standard local key lookup, done before any of the mechanisms defined by the --auto-key- locate are tried. The position of this mechanism in the list does not matter. It is not required if local is also used.
--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 conve- nient) 16-character key ID. Add an "0x" to either to include an "0x" at the beginning of the key ID, as in 0x99242560. Note that this option is ignored if the option --with-colons is used.
--keyserver name 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. Key- server 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 gener- ally no need to send keys to more than one server. The keyserver hkp://keys.gnupg.net uses round robin DNS to give a different keyserver each time you use it.
--keyserver-options name=value1 This is a space or comma delimited string that gives options for the keyserver. Options can be prefixed with a `no-' to give the opposite meaning. Valid import-options or export-options may be used here as well to apply to importing (--recv-key) or export- ing (--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-keyretrieve 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 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 Set the proxy to use for HTTP and HKP keyservers. This overrides the "http_proxy" environment variable, if any.
max-cert-size When retrieving a key via DNS CERT, only accept keys up to this size. Defaults to 16384 bytes.
debug Turn on debug output in the keyserver helper program. Note that the details of debug output depends on which keyserver helper program is being used, and in turn, on any libraries that the keyserver helper program uses internally (libcurl, openldap, etc).
check-cert Enable certificate checking if the keyserver presents one (for hkps or ldaps). Defaults to on.
ca-cert-file Provide a certificate store to override the system default. Only necessary if check-cert is enabled, and the keyserver is using a certificate that is not present in a system default certificate list.
Note that depending on the SSL library that the keyserver helper is built with, this may actually be a directory or a file.
--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).
--simple-sk-checksum Secret keys are integrity protected by using a SHA-1 checksum. This method is part of the upcoming enhanced OpenPGP specifica- tion but GnuPG already uses it as a countermeasure against cer- tain attacks. Old applications don't understand this new for- mat, so this option may be used to switch back to the old behav- iour. 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).
--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 modi- fications, 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 pub- lic 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 cre- ation needs manual interaction, this performance penalty does not matter in most settings.
--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.
--no-use-agent Try to use the GnuPG-Agent. 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. Given that this option is not anymore used by gpg2, it should be avoided if possible.
--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 immedi- ately 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 invoca- tions. This makes random generation faster; however sometimes write operations are not desired. This option can be used to achieve that with the cost of slower random generation.
--no-greeting Suppress the initial copyright message.
--no-secmem-warning Suppress the warning about "using insecure memory".
--no-permission-warning Suppress the warning about unsafe file and home directory (--homedir) permissions. Note that the permission checks that GnuPG performs are not intended to be authoritative, but rather they simply warn about certain common permission problems. Do not assume that the lack of a warning means that your system is secure.
Note that the warning for unsafe --homedir permissions cannot be suppressed in the gpg.conf file, as this would allow an attacker to place an unsafe gpg.conf file in place, and use this file to suppress warnings about itself. The --homedir permissions warn- ing may only be suppressed on the command line.
--no-mdc-warning Suppress the warning about missing MDC integrity protection.
--no-require-secmem Refuse to run if GnuPG cannot get secure memory. Defaults to no (i.e. run, but give a warning).
--no-require-cross-certification When verifying a signature made from a subkey, ensure that the cross certification "back signature" on the subkey is present and valid. This protects against a subtle attack against sub- keys that can sign. Defaults to --require-cross-certification for gpg.
--no-expert Allow the user to do certain nonsensical or "silly" things like signing an expired or revoked key, or certain potentially incom- patible things like generating unusual key types. This also dis- ables 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.