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- wheezy 1.4.12-7+deb7u7
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- testing 2.1.18-6
- unstable 2.1.18-8
- experimental 2.1.21-2
GPG(1) | GNU Privacy Guard | GPG(1) |
NAME¶
gpg - OpenPGP encryption and signing toolSYNOPSIS¶
gpg [--homedir dir] [--options file] [options] command [args]DESCRIPTION¶
gpg is the OpenPGP part of the GNU Privacy Guard (GnuPG). It is a tool to provide digital encryption and signing services using the OpenPGP standard. gpg features complete key management and all bells and whistles you can expect from a decent OpenPGP implementation.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.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.INTEROPERABILITY¶
GnuPG tries to be a very flexible implementation of the OpenPGP standard. In particular, GnuPG implements many of the optional parts of the standard, such as the SHA-512 hash, and the ZLIB and BZIP2 compression algorithms. It is important to be aware that not all OpenPGP programs implement these optional algorithms and that by forcing their use via the --cipher-algo, --digest-algo, --cert-digest-algo, or --compress-algo options in GnuPG, it is possible to create a perfectly valid OpenPGP message, but one that cannot be read by the intended recipient.COMMANDS¶
Commands are not distinguished from options except for the fact that only one command is allowed.Commands not specific to the function¶
- --version
- Print the program version and licensing information. Note
that you cannot abbreviate this command.
- --help
- -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¶
- --sign
- -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.
- --detach-sign
- -b
- Make a detached signature.
- --encrypt
- -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).
- --symmetric
- -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).
- --decrypt
- -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-keys
- -k
- --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.
- --list-secret-keys
- -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.
- --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.
- --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 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.
- --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-keys
- --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-checksum if you want to import such an
exported key with an older OpenPGP implementation.
- --import
- --fast-import
- Import/merge keys. This adds the given keys to the keyring.
The fast version is currently just a synonym.
- --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-keyserver-url).
- --search-keys names
- Search the keyserver for the given names. Multiple names
given here will be joined together to create the search string for the
keyserver. Option --keyserver must be used to give the name of this
keyserver. Keyservers that support different search methods allow using
the syntax specified in "How to specify a user ID" below. Note
that different keyserver types support different search methods. Currently
only LDAP supports them all.
- --fetch-keys URIs
- Retrieve keys located at the specified URIs. Note that
different installations of GnuPG may support different protocols (HTTP,
FTP, LDAP, etc.)
- --update-trustdb
- Do trust database maintenance. This command iterates over
all keys and builds the Web of Trust. This is an interactive command
because it may have to ask for the "ownertrust" values for keys.
The user has to give an estimation of how far she trusts the owner of the
displayed key to correctly certify (sign) other keys. GnuPG only asks for
the ownertrust value if it has not yet been assigned to a key. Using the
--edit-key menu, the assigned value can be changed at any time.
- --check-trustdb
- Do trust database maintenance without user interaction.
From time to time the trust database must be updated so that expired keys
or signatures and the resulting changes in the Web of Trust can be
tracked. Normally, GnuPG will calculate when this is required and do it
automatically unless --no-auto-check-trustdb is set. This command
can be used to force a trust database check at any time. The processing is
identical to that of --update-trustdb but it skips keys with a not
yet defined "ownertrust".
- --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 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-md algo
- --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.
- --enarmor
- --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¶
- --gen-key
- Generate a new key pair. This command is normally only used
interactively.
- --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-keyserver-url for more on how this
works. Setting a value of "none" removes an existing preferred
keyserver.
- notation
- Set a name=value notation for the specified user ID(s). See
--cert-notation for more on how this works. Setting a value of
"none" removes all notations, setting a notation prefixed with a
minus sign (-) removes that notation, and setting a notation name (without
the =value) prefixed with a minus sign removes all notations with that
name.
- 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.
- 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.
- disable
- 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.
OPTIONS¶
gpg features a bunch of options to control the exact behaviour and to change the default configuration.How to change the configuration¶
- --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.
- --batch
- --no-batch
- Use batch mode. Never ask, do not allow interactive
commands. --no-batch disables this option. Note that even with a
filename given on the command line, gpg might still need to read from
STDIN (in particular if gpg figures that the input is a detached signature
and no data file has been specified). Thus if you do not want to feed data
via STDIN, you should connect STDIN to ‘ /dev/null’.
- --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-notations
- show-std-notations
- show-user-notations
- Show all, IETF standard, or user-defined signature
notations in the --list-sigs or --check-sigs listings.
Defaults to no.
- show-keyserver-urls
- Show any preferred keyserver URL in the --list-sigs
or --check-sigs listings. Defaults to no.
- show-uid-validity
- Display the calculated validity of user IDs during key
listings. Defaults to no.
- show-unusable-uids
- Show revoked and expired user IDs in key listings. Defaults
to no.
- show-unusable-subkeys
- Show revoked and expired subkeys in key listings. Defaults
to no.
- show-keyring
- Display the keyring name at the head of key listings to
show which keyring a given key resides on. Defaults to no.
- show-sig-expire
- Show signature expiration dates (if any) during
--list-sigs or --check-sigs listings. Defaults to no.
- show-sig-subpackets
- Include signature subpackets in the key listing. This
option can take an optional argument list of the subpackets to list. If no
argument is passed, list all subpackets. Defaults to no. This option is
only meaningful when using --with-colons along with
--list-sigs or --check-sigs.
- --verify-options parameters
- This is a space or comma delimited string that gives
options used when verifying signatures. Options can be prepended with a
`no-' to give the opposite meaning. The options are:
- show-photos
- Display any photo IDs present on the key that issued the
signature. Defaults to no. See also --photo-viewer.
- show-policy-urls
- Show policy URLs in the signature being verified. Defaults
to no.
- show-notations
- show-std-notations
- show-user-notations
- Show all, IETF standard, or user-defined signature
notations in the signature being verified. Defaults to IETF standard.
- show-keyserver-urls
- Show any preferred keyserver URL in the signature being
verified. Defaults to no.
- show-uid-validity
- Display the calculated validity of the user IDs on the key
that issued the signature. Defaults to no.
- show-unusable-uids
- Show revoked and expired user IDs during signature
verification. Defaults to no.
- 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.
- --enable-dsa2
- --disable-dsa2
- Enable hash truncation for all DSA keys even for old DSA
Keys up to 1024 bit. This is also the default with --openpgp. Note
that older versions of GnuPG also required this flag to allow the
generation of DSA larger than 1024 bit.
- --photo-viewer string
- This is the command line that should be run to view a photo
ID. "%i" will be expanded to a filename containing the photo.
"%I" does the same, except the file will not be deleted once the
viewer exits. Other flags are "%k" for the key ID,
"%K" for the long key ID, "%f" for the key
fingerprint, "%t" for the extension of the image type (e.g.
"jpg"), "%T" for the MIME type of the image (e.g.
"image/jpeg"), "%v" for the single-character
calculated validity of the image being viewed (e.g. "f"),
"%V" for the calculated validity as a string (e.g.
"full"), 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.
- --exec-path string
- Sets a list of directories to search for photo viewers and
keyserver helpers. If not provided, keyserver helpers use the compiled-in
default directory, and photo viewers use the $PATH environment variable.
Note, that on W32 system this value is ignored when searching for
keyserver helpers.
- --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).
- --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,
`/System/Library/Frameworks/PCSC.framework/PCSC' for MAC OS X,
`winscard.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 support is only
available if libusb was available at build time.
- --reader-port number_or_string
- This option may be used to specify the port of the card
terminal. A value of 0 refers to the first serial device; add 32768 to
access USB devices. The default is 32768 (first USB device). PC/SC or CCID
readers might need a string here; run the program in verbose mode to get a
list of available readers. The default is then the first reader found.
- --display-charset name
- Set the name of the native character set. This is used to
convert some informational strings like user IDs to the proper UTF-8
encoding. Note that this has nothing to do with the character set of data
to be encrypted or signed; GnuPG does not recode user-supplied data. If
this option is not used, the default character set is determined from the
current locale. A verbosity level of 3 shows the chosen set. Valid values
for name are:
- iso-8859-1
- This is the Latin 1 set.
- iso-8859-2
- The Latin 2 set.
- iso-8859-15
- This is currently an alias for the Latin 1 set.
- koi8-r
- The usual Russian set (rfc1489).
- utf-8
- Bypass all translations and assume that the OS uses native UTF-8 encoding.
- --utf8-strings
- --no-utf8-strings
- Assume that command line arguments are given as UTF8
strings. The default ( --no-utf8-strings) is to assume that
arguments are encoded in the character set as specified by
--display-charset. These options affect all following arguments.
Both options may be used multiple times.
- --options file
- Read options from file and do not try to read them
from the default options file in the homedir (see --homedir). This
option is ignored if used in an options file.
- --no-options
- Shortcut for --options /dev/null. This option is
detected before an attempt to open an option file. Using this option will
also prevent the creation of a ‘ ~/.gnupg’ homedir.
- -z n
- --compress-level n
- --bzip2-compress-level n
- Set compression level to n for the ZIP and ZLIB
compression algorithms. The default is to use the default compression
level of zlib (normally 6). --bzip2-compress-level sets the
compression level for the BZIP2 compression algorithm (defaulting to 6 as
well). This is a different option from --compress-level since BZIP2
uses a significant amount of memory for each additional compression level.
-z sets both. A value of 0 for n disables compression.
- --bzip2-decompress-lowmem
- Use a different decompression method for BZIP2 compressed
files. This alternate method uses a bit more than half the memory, but
also runs at half the speed. This is useful under extreme low memory
circumstances when the file was originally compressed at a high
--bzip2-compress-level.
- --mangle-dos-filenames
- --no-mangle-dos-filenames
- Older version of Windows cannot handle filenames with more
than one dot. --mangle-dos-filenames causes GnuPG to replace
(rather than add to) the extension of an output filename to avoid this
problem. This option is off by default and has no effect on non-Windows
platforms.
- --ask-cert-level
- --no-ask-cert-level
- When making a key signature, prompt for a certification
level. If this option is not specified, the certification level used is
set via --default-cert-level. See --default-cert-level for
information on the specific levels and how they are used.
--no-ask-cert-level disables this option. This option defaults to
no.
- --default-cert-level n
- The default to use for the check level when signing a key.
- --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.
- --auto-key-locate parameters
- --no-auto-key-locate
- GnuPG can automatically locate and retrieve keys as needed
using this option. This happens when encrypting to an email address (in
the "user@example.com" form), and there are no user@example.com
keys on the local keyring. This option takes any number of the following
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 convenient) 16-character key ID. Add an "0x" to either to
include an "0x" at the beginning of the key ID, as in
0x99242560. Note that this option is ignored if the option --with-colons
is used.
- --keyserver name
- Use name as your keyserver. This is the server that
--recv-keys, --send-keys, and --search-keys will
communicate with to receive keys from, send keys to, and search for keys
on. The format of the name is a URI:
`scheme:[//]keyservername[:port]' The scheme is the type of keyserver:
"hkp" for the HTTP (or compatible) keyservers, "ldap"
for the LDAP keyservers, or "mailto" for the Graff email
keyserver. Note that your particular installation of GnuPG may have other
keyserver types available as well. Keyserver schemes are case-insensitive.
After the keyserver name, optional keyserver configuration options may be
provided. These are the same as the global --keyserver-options from
below, but apply only to this particular keyserver.
- --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 exporting (
--send-key) a key from a keyserver. While not all options are
available for all keyserver types, some common options are:
- include-revoked
- When searching for a key with --search-keys, include
keys that are marked on the keyserver as revoked. Note that not all
keyservers differentiate between revoked and unrevoked keys, and for such
keyservers this option is meaningless. Note also that most keyservers do
not have cryptographic verification of key revocations, and so turning
this option off may result in skipping keys that are incorrectly marked as
revoked.
- include-disabled
- When searching for a key with --search-keys, include
keys that are marked on the keyserver as disabled. Note that this option
is not used with HKP keyservers.
- auto-key-retrieve
- This option enables the automatic retrieving of keys from a
keyserver when verifying signatures made by keys that are not on the local
keyring.
- honor-keyserver-url
- When using --refresh-keys, if the key in question
has a preferred keyserver URL, then use that preferred keyserver to
refresh the key from. In addition, if auto-key-retrieve is set, and the
signature being verified has a preferred keyserver URL, then use that
preferred keyserver to fetch the key from. Defaults to yes.
- honor-pka-record
- If auto-key-retrieve is set, and the signature being
verified has a PKA record, then use the PKA information to fetch the key.
Defaults to yes.
- include-subkeys
- When receiving a key, include subkeys as potential targets.
Note that this option is not used with HKP keyservers, as they do not
support retrieving keys by subkey id.
- use-temp-files
- On most Unix-like platforms, GnuPG communicates with the
keyserver helper program via pipes, which is the most efficient method.
This option forces GnuPG to use temporary files to communicate. On some
platforms (such as Win32 and RISC OS), this option is always enabled.
- keep-temp-files
- If using `use-temp-files', do not delete the temp files
after using them. This option is useful to learn the keyserver
communication protocol by reading the temporary files.
- verbose
- Tell the keyserver helper program to be more verbose. This
option can be repeated multiple times to increase the verbosity level.
- timeout
- 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.
- --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
specification but GnuPG already uses it as a countermeasure against
certain attacks. Old applications don't understand this new format, so
this option may be used to switch back to the old behaviour. Using this
option bears a security risk. Note that using this option only takes
effect when the secret key is encrypted - the simplest way to make this
happen is to change the passphrase on the key (even changing it to the
same value is acceptable).
- --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.
- --use-agent
- --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
immediately terminate the process. That should in fact be the default but
it never worked this way and thus we need an option to enable this, so
that the change won't break applications which close their end of a status
fd connected pipe too early. Using this option along with
--enable-progress-filter may be used to cleanly cancel long running
gpg operations.
- --limit-card-insert-tries n
- With n greater than 0 the number of prompts asking
to insert a smartcard gets limited to N-1. Thus with a value of 1 gpg
won't at all ask to insert a card if none has been inserted at startup.
This option is useful in the configuration file in case an application
does not know about the smartcard support and waits ad infinitum for an
inserted card.
- --no-random-seed-file
- GnuPG uses a file to store its internal random pool over
invocations. This makes random generation faster; however sometimes write
operations are not desired. This option can be used to achieve that with
the cost of slower random generation.
- --no-greeting
- Suppress the initial copyright message.
- --no-secmem-warning
- Suppress the warning about "using insecure
memory".
- --no-permission-warning
- Suppress the warning about unsafe file and home directory
(--homedir) permissions. Note that the permission checks that GnuPG
performs are not intended to be authoritative, but rather they simply warn
about certain common permission problems. Do not assume that the lack of a
warning means that your system is secure.
- --no-mdc-warning
- Suppress the warning about missing MDC integrity
protection.
- --require-secmem
- --no-require-secmem
- Refuse to run if GnuPG cannot get secure memory. Defaults
to no (i.e. run, but give a warning).
- --require-cross-certification
- --no-require-cross-certification
- When verifying a signature made from a subkey, ensure that
the cross certification "back signature" on the subkey is
present and valid. This protects against a subtle attack against subkeys
that can sign. Defaults to --require-cross-certification for
gpg.
- --expert
- --no-expert
- Allow the user to do certain nonsensical or
"silly" things like signing an expired or revoked key, or
certain potentially incompatible things like generating unusual key types.
This also disables certain warning messages about potentially incompatible
actions. As the name implies, this option is for experts only. If you
don't fully understand the implications of what it allows you to do, leave
this off. --no-expert disables this option.
Key related options¶
- --recipient name
- -r
- Encrypt for user id name. If this option or
--hidden-recipient is not specified, GnuPG asks for the user-id
unless --default-recipient is given.
- --hidden-recipient name
- -R
- Encrypt for user ID name, but hide the key ID of
this user's key. This option helps to hide the receiver of the message and
is a limited countermeasure against traffic analysis. If this option or
--recipient is not specified, GnuPG asks for the user ID unless
--default-recipient is given.
- --encrypt-to name
- Same as --recipient but this one is intended for use
in the options file and may be used with your own user-id as an
"encrypt-to-self". These keys are only used when there are other
recipients given either by use of --recipient or by the asked user
id. No trust checking is performed for these user ids and even disabled
keys can be used.
- --hidden-encrypt-to name
- Same as --hidden-recipient but this one is intended
for use in the options file and may be used with your own user-id as a
hidden "encrypt-to-self". These keys are only used when there
are other recipients given either by use of --recipient or by the
asked user id. No trust checking is performed for these user ids and even
disabled keys can be used.
- --no-encrypt-to
- Disable the use of all --encrypt-to and
--hidden-encrypt-to keys.
- --group name=value1
- Sets up a named group, which is similar to aliases in email
programs. Any time the group name is a recipient ( -r or
--recipient), it will be expanded to the values specified. Multiple
groups with the same name are automatically merged into a single group.
- --ungroup name
- Remove a given entry from the --group list.
- --no-groups
- Remove all entries from the --group list.
- --local-user name
- -u
- Use name as the key to sign with. Note that this
option overrides --default-key.
- --try-secret-key name
- For hidden recipients GPG needs to know the keys to use for
trial decryption. The key set with --default-key is always tried
first, but this is often not sufficient. This option allows to set more
keys to be used for trial decryption. Although any valid user-id
specification may be used for name it makes sense to use at least
the long keyid to avoid ambiguities. Note that gpg-agent might pop up a
pinentry for a lot keys to do the trial decryption. If you want to stop
all further trial decryption you may use close-window button instead of
the cancel button.
- --try-all-secrets
- Don't look at the key ID as stored in the message but try
all secret keys in turn to find the right decryption key. This option
forces the behaviour as used by anonymous recipients (created by using
--throw-keyids or --hidden-recipient) and might come handy
in case where an encrypted message contains a bogus key ID.
- --skip-hidden-recipients
- --no-skip-hidden-recipients
- During decryption skip all anonymous recipients. This
option helps in the case that people use the hidden recipients feature to
hide there own encrypt-to key from others. If oneself has many secret keys
this may lead to a major annoyance because all keys are tried in turn to
decrypt soemthing which was not really intended for it. The drawback of
this option is that it is currently not possible to decrypt a message
which includes real anonymous recipients.
Input and Output¶
- --armor
- -a
- Create ASCII armored output. The default is to create the
binary OpenPGP format.
- --no-armor
- Assume the input data is not in ASCII armored format.
- --output file
- -o file
- Write output to file.
- --max-output n
- This option sets a limit on the number of bytes that will
be generated when processing a file. Since OpenPGP supports various levels
of compression, it is possible that the plaintext of a given message may
be significantly larger than the original OpenPGP message. While GnuPG
works properly with such messages, there is often a desire to set a
maximum file size that will be generated before processing is forced to
stop by the OS limits. Defaults to 0, which means "no limit".
- --import-options parameters
- This is a space or comma delimited string that gives
options for importing keys. Options can be prepended with a `no-' to give
the opposite meaning. The options are:
- import-local-sigs
- Allow importing key signatures marked as "local".
This is not generally useful unless a shared keyring scheme is being used.
Defaults to no.
- repair-pks-subkey-bug
- During import, attempt to repair the damage caused by the
PKS keyserver bug (pre version 0.9.6) that mangles keys with multiple
subkeys. Note that this cannot completely repair the damaged key as some
crucial data is removed by the keyserver, but it does at least give you
back one subkey. Defaults to no for regular --import and to yes for
keyserver --recv-keys.
- merge-only
- During import, allow key updates to existing keys, but do
not allow any new keys to be imported. Defaults to no.
- import-clean
- After import, compact (remove all signatures except the
self-signature) any user IDs from the new key that are not usable. Then,
remove any signatures from the new key that are not usable. This includes
signatures that were issued by keys that are not present on the keyring.
This option is the same as running the --edit-key command
"clean" after import. Defaults to no.
- import-minimal
- Import the smallest key possible. This removes all signatures except the most recent self-signature on each user ID. This option is the same as running the --edit-key command "minimize" after import. Defaults to no.
- --export-options parameters
- This is a space or comma delimited string that gives
options for exporting keys. Options can be prepended with a `no-' to give
the opposite meaning. The options are:
- export-local-sigs
- Allow exporting key signatures marked as "local".
This is not generally useful unless a shared keyring scheme is being used.
Defaults to no.
- export-attributes
- Include attribute user IDs (photo IDs) while exporting.
This is useful to export keys if they are going to be used by an OpenPGP
program that does not accept attribute user IDs. Defaults to yes.
- export-sensitive-revkeys
- Include designated revoker information that was marked as
"sensitive". Defaults to no.
- export-reset-subkey-passwd
- When using the --export-secret-subkeys command, this
option resets the passphrases for all exported subkeys to empty. This is
useful when the exported subkey is to be used on an unattended machine
where a passphrase doesn't necessarily make sense. Defaults to no.
- export-clean
- Compact (remove all signatures from) user IDs on the key
being exported if the user IDs are not usable. Also, do not export any
signatures that are not usable. This includes signatures that were issued
by keys that are not present on the keyring. This option is the same as
running the --edit-key command "clean" before export
except that the local copy of the key is not modified. Defaults to no.
- export-minimal
- Export the smallest key possible. This removes all signatures except the most recent self-signature on each user ID. This option is the same as running the --edit-key command "minimize" before export except that the local copy of the key is not modified. Defaults to no.
- --with-colons
- Print key listings delimited by colons. Note that the
output will be encoded in UTF-8 regardless of any --display-charset
setting. This format is useful when GnuPG is called from scripts and other
programs as it is easily machine parsed. The details of this format are
documented in the file ‘ doc/DETAILS’, which is
included in the GnuPG source distribution.
- --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.
- --with-fingerprint
- Same as the command --fingerprint but changes only
the format of the output and may be used together with another command.
- --with-keygrip
- Include the keygrip in the key listings.
OpenPGP protocol specific options.¶
- -t, --textmode
- --no-textmode
- Treat input files as text and store them in the OpenPGP
canonical text form with standard "CRLF" line endings. This also
sets the necessary flags to inform the recipient that the encrypted or
signed data is text and may need its line endings converted back to
whatever the local system uses. This option is useful when communicating
between two platforms that have different line ending conventions
(UNIX-like to Mac, Mac to Windows, etc). --no-textmode disables
this option, and is the default.
- --force-v3-sigs
- --no-force-v3-sigs
- OpenPGP states that an implementation should generate v4
signatures but PGP versions 5 through 7 only recognize v4 signatures on
key material. This option forces v3 signatures for signatures on data.
Note that this option implies --no-ask-sig-expire, and unsets
--sig-policy-url, --sig-notation, and
--sig-keyserver-url, as these features cannot be used with v3
signatures. --no-force-v3-sigs disables this option. Defaults to
no.
- --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.
- --personal-cipher-preferences string
- Set the list of personal cipher preferences to
string. Use gpg --version to get a list of available
algorithms, and use none to set no preference at all. This allows
the user to safely override the algorithm chosen by the recipient key
preferences, as GPG will only select an algorithm that is usable by all
recipients. The most highly ranked cipher in this list is also used for
the --symmetric encryption command.
- --personal-digest-preferences string
- Set the list of personal digest preferences to
string. Use gpg --version to get a list of available
algorithms, and use none to set no preference at all. This allows
the user to safely override the algorithm chosen by the recipient key
preferences, as GPG will only select an algorithm that is usable by all
recipients. The most highly ranked digest algorithm in this list is also
used when signing without encryption (e.g. --clearsign or
--sign).
- --personal-compress-preferences string
- Set the list of personal compression preferences to
string. Use gpg --version to get a list of available
algorithms, and use none to set no preference at all. This allows
the user to safely override the algorithm chosen by the recipient key
preferences, as GPG will only select an algorithm that is usable by all
recipients. The most highly ranked compression algorithm in this list is
also used when there are no recipient keys to consider (e.g.
--symmetric).
- --s2k-cipher-algo name
- Use name as the cipher algorithm used to protect
secret keys. The default cipher is CAST5. This cipher is also used for
conventional encryption if --personal-cipher-preferences and
--cipher-algo is not given.
- --s2k-digest-algo name
- Use name as the digest algorithm used to mangle the
passphrases. The default algorithm is SHA-1.
- --s2k-mode n
- Selects how passphrases are mangled. If n is 0 a
plain passphrase (which is not recommended) will be used, a 1 adds a salt
to the passphrase and a 3 (the default) iterates the whole process a
number of times (see --s2k-count). Unless --rfc1991 is used, this
mode is also used for conventional encryption.
- --s2k-count n
- Specify how many times the passphrase mangling is repeated.
This value may range between 1024 and 65011712 inclusive. The default is
inquired from gpg-agent. Note that not all values in the 1024-65011712
range are legal and if an illegal value is selected, GnuPG will round up
to the nearest legal value. This option is only meaningful if
--s2k-mode is 3.
Compliance options¶
- --gnupg
- Use standard GnuPG behavior. This is essentially OpenPGP
behavior (see --openpgp), but with some additional workarounds for
common compatibility problems in different versions of PGP. This is the
default option, so it is not generally needed, but it may be useful to
override a different compliance option in the gpg.conf file.
- --openpgp
- Reset all packet, cipher and digest options to strict
OpenPGP behavior. Use this option to reset all previous options like
--s2k-*, --cipher-algo, --digest-algo and
--compress-algo to OpenPGP compliant values. All PGP workarounds
are disabled.
- --rfc4880
- Reset all packet, cipher and digest options to strict
RFC-4880 behavior. Note that this is currently the same thing as
--openpgp.
- --rfc2440
- Reset all packet, cipher and digest options to strict
RFC-2440 behavior.
- --rfc1991
- Try to be more RFC-1991 (PGP 2.x) compliant.
- --pgp2
- Set up all options to be as PGP 2.x compliant as possible,
and warn if an action is taken (e.g. encrypting to a non-RSA key) that
will create a message that PGP 2.x will not be able to handle. Note that
`PGP 2.x' here means `MIT PGP 2.6.2'. There are other versions of PGP 2.x
available, but the MIT release is a good common baseline.
- --pgp6
- Set up all options to be as PGP 6 compliant as possible.
This restricts you to the ciphers IDEA (if the IDEA plugin is installed),
3DES, and CAST5, the hashes MD5, SHA1 and RIPEMD160, and the compression
algorithms none and ZIP. This also disables --throw-keyids, and making
signatures with signing subkeys as PGP 6 does not understand signatures
made by signing subkeys.
- --pgp7
- Set up all options to be as PGP 7 compliant as possible.
This is identical to --pgp6 except that MDCs are not disabled, and
the list of allowable ciphers is expanded to add AES128, AES192, AES256,
and TWOFISH.
- --pgp8
- Set up all options to be as PGP 8 compliant as possible.
PGP 8 is a lot closer to the OpenPGP standard than previous versions of
PGP, so all this does is disable --throw-keyids and set
--escape-from-lines. All algorithms are allowed except for the
SHA224, SHA384, and SHA512 digests.
Doing things one usually doesn't want to do.¶
- -n
- --dry-run
- Don't make any changes (this is not completely
implemented).
- --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.
- -i
- --interactive
- Prompt before overwriting any files.
- --debug-level level
- Select the debug level for investigating problems.
level may be a numeric value or by a keyword:
- none
- No debugging at all. A value of less than 1 may be used instead of the keyword.
- basic
- Some basic debug messages. A value between 1 and 2 may be used instead of the keyword.
- advanced
- More verbose debug messages. A value between 3 and 5 may be used instead of the keyword.
- expert
- Even more detailed messages. A value between 6 and 8 may be used instead of the keyword.
- guru
- All of the debug messages you can get. A value greater than 8 may be used instead of the keyword. The creation of hash tracing files is only enabled if the keyword is used.
- --debug flags
- Set debugging flags. All flags are or-ed and flags
may be given in C syntax (e.g. 0x0042).
- --debug-all
- Set all useful debugging flags.
- --debug-ccid-driver
- Enable debug output from the included CCID driver for
smartcards. Note that this option is only available on some system.
- --faked-system-time epoch
- This option is only useful for testing; it sets the system
time back or forth to epoch which is the number of seconds elapsed
since the year 1970. Alternatively epoch may be given as a full ISO
time string (e.g. "20070924T154812").
- --enable-progress-filter
- Enable certain PROGRESS status outputs. This option allows
frontends to display a progress indicator while gpg is processing larger
files. There is a slight performance overhead using it.
- --status-fd n
- Write special status strings to the file descriptor
n. See the file DETAILS in the documentation for a listing of them.
- --status-file file
- Same as --status-fd, except the status data is
written to file file.
- --logger-fd n
- Write log output to file descriptor n and not to
STDERR.
- --log-file file
- --logger-file file
- Same as --logger-fd, except the logger data is
written to file file. Note that --log-file is only
implemented for GnuPG-2.
- --attribute-fd n
- Write attribute subpackets to the file descriptor n.
This is most useful for use with --status-fd, since the status
messages are needed to separate out the various subpackets from the stream
delivered to the file descriptor.
- --attribute-file file
- Same as --attribute-fd, except the attribute data is
written to file file.
- --comment string
- --no-comments
- Use string as a comment string in clear text
signatures and ASCII armored messages or keys (see --armor). The
default behavior is not to use a comment string. --comment may be
repeated multiple times to get multiple comment strings.
--no-comments removes all comments. It is a good idea to keep the
length of a single comment below 60 characters to avoid problems with mail
programs wrapping such lines. Note that comment lines, like all other
header lines, are not protected by the signature.
- --emit-version
- --no-emit-version
- Force inclusion of the version string in ASCII armored
output. --no-emit-version disables this option.
- --sig-notation name=value
- --cert-notation name=value
- -N, --set-notation name=value
- Put the name value pair into the signature as notation
data. name must consist only of printable characters or spaces, and
must contain a '@' character in the form keyname@domain.example.com
(substituting the appropriate keyname and domain name, of course). This is
to help prevent pollution of the IETF reserved notation namespace. The
--expert flag overrides the '@' check. value may be any
printable string; it will be encoded in UTF8, so you should check that
your --display-charset is set correctly. If you prefix name
with an exclamation mark (!), the notation data will be flagged as
critical (rfc2440:5.2.3.15). --sig-notation sets a notation for
data signatures. --cert-notation sets a notation for key signatures
(certifications). --set-notation sets both.
- --sig-policy-url string
- --cert-policy-url string
- --set-policy-url string
- Use string as a Policy URL for signatures
(rfc2440:5.2.3.19). If you prefix it with an exclamation mark (!), the
policy URL packet will be flagged as critical. --sig-policy-url
sets a policy url for data signatures. --cert-policy-url sets a
policy url for key signatures (certifications). --set-policy-url
sets both.
- --sig-keyserver-url string
- Use string as a preferred keyserver URL for data
signatures. If you prefix it with an exclamation mark (!), the keyserver
URL packet will be flagged as critical.
- --set-filename string
- Use string as the filename which is stored inside
messages. This overrides the default, which is to use the actual filename
of the file being encrypted.
- --for-your-eyes-only
- --no-for-your-eyes-only
- Set the `for your eyes only' flag in the message. This
causes GnuPG to refuse to save the file unless the --output option
is given, and PGP to use a "secure viewer" with a claimed
Tempest-resistant font to display the message. This option overrides
--set-filename. --no-for-your-eyes-only disables this
option.
- --use-embedded-filename
- --no-use-embedded-filename
- Try to create a file with a name as embedded in the data.
This can be a dangerous option as it allows to overwrite files. Defaults
to no.
- --cipher-algo name
- Use name as cipher algorithm. Running the program
with the command --version yields a list of supported algorithms.
If this is not used the cipher algorithm is selected from the preferences
stored with the key. In general, you do not want to use this option as it
allows you to violate the OpenPGP standard.
--personal-cipher-preferences is the safe way to accomplish the
same thing.
- --digest-algo name
- Use name as the message digest algorithm. Running
the program with the command --version yields a list of supported
algorithms. In general, you do not want to use this option as it allows
you to violate the OpenPGP standard. --personal-digest-preferences
is the safe way to accomplish the same thing.
- --compress-algo name
- Use compression algorithm name. "zlib" is
RFC-1950 ZLIB compression. "zip" is RFC-1951 ZIP compression
which is used by PGP. "bzip2" is a more modern compression
scheme that can compress some things better than zip or zlib, but at the
cost of more memory used during compression and decompression.
"uncompressed" or "none" disables compression. If this
option is not used, the default behavior is to examine the recipient key
preferences to see which algorithms the recipient supports. If all else
fails, ZIP is used for maximum compatibility.
- --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.
- --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.
- --throw-keyids
- --no-throw-keyids
- Do not put the recipient key IDs into encrypted messages.
This helps to hide the receivers of the message and is a limited
countermeasure against traffic analysis. ([Using a little social
engineering anyone who is able to decrypt the message can check whether
one of the other recipients is the one he suspects.]) On the receiving
side, it may slow down the decryption process because all available secret
keys must be tried. --no-throw-keyids disables this option. This
option is essentially the same as using --hidden-recipient for all
recipients.
- --not-dash-escaped
- This option changes the behavior of cleartext signatures so
that they can be used for patch files. You should not send such an armored
file via email because all spaces and line endings are hashed too. You can
not use this option for data which has 5 dashes at the beginning of a
line, patch files don't have this. A special armor header line tells GnuPG
about this cleartext signature option.
- --escape-from-lines
- --no-escape-from-lines
- Because some mailers change lines starting with "From
" to ">From " it is good to handle such lines in a
special way when creating cleartext signatures to prevent the mail system
from breaking the signature. Note that all other PGP versions do it this
way too. Enabled by default. --no-escape-from-lines disables this
option.
- --passphrase-repeat n
- Specify how many times gpg will request a new
passphrase be repeated. This is useful for helping memorize a passphrase.
Defaults to 1 repetition.
- --passphrase-fd n
- Read the passphrase from file descriptor n. Only the
first line will be read from file descriptor n. If you use 0 for
n, the passphrase will be read from STDIN. This can only be used if
only one passphrase is supplied.
- --passphrase-file file
- Read the passphrase from file file. Only the first
line will be read from file file. This can only be used if only one
passphrase is supplied. Obviously, a passphrase stored in a file is of
questionable security if other users can read this file. Don't use this
option if you can avoid it.
- --passphrase string
- Use string as the passphrase. This can only be used
if only one passphrase is supplied. Obviously, this is of very
questionable security on a multi-user system. Don't use this option if you
can avoid it.
- --command-fd n
- This is a replacement for the deprecated shared-memory IPC
mode. If this option is enabled, user input on questions is not expected
from the TTY but from the given file descriptor. It should be used
together with --status-fd. See the file doc/DETAILS in the source
distribution for details on how to use it.
- --command-file file
- Same as --command-fd, except the commands are read
out of file file
- --allow-non-selfsigned-uid
- --no-allow-non-selfsigned-uid
- Allow the import and use of keys with user IDs which are
not self-signed. This is not recommended, as a non self-signed user ID is
trivial to forge. --no-allow-non-selfsigned-uid disables.
- --allow-freeform-uid
- Disable all checks on the form of the user ID while
generating a new one. This option should only be used in very special
environments as it does not ensure the de-facto standard format of user
IDs.
- --ignore-time-conflict
- GnuPG normally checks that the timestamps associated with
keys and signatures have plausible values. However, sometimes a signature
seems to be older than the key due to clock problems. This option makes
these checks just a warning. See also --ignore-valid-from for
timestamp issues on subkeys.
- --ignore-valid-from
- GnuPG normally does not select and use subkeys created in
the future. This option allows the use of such keys and thus exhibits the
pre-1.0.7 behaviour. You should not use this option unless there is some
clock problem. See also --ignore-time-conflict for timestamp issues
with signatures.
- --ignore-crc-error
- The ASCII armor used by OpenPGP is protected by a CRC
checksum against transmission errors. Occasionally the CRC gets mangled
somewhere on the transmission channel but the actual content (which is
protected by the OpenPGP protocol anyway) is still okay. This option
allows GnuPG to ignore CRC errors.
- --ignore-mdc-error
- This option changes a MDC integrity protection failure into
a warning. This can be useful if a message is partially corrupt, but it is
necessary to get as much data as possible out of the corrupt message.
However, be aware that a MDC protection failure may also mean that the
message was tampered with intentionally by an attacker.
- --no-default-keyring
- Do not add the default keyrings to the list of keyrings.
Note that GnuPG will not operate without any keyrings, so if you use this
option and do not provide alternate keyrings via --keyring or
--secret-keyring, then GnuPG will still use the default public or
secret keyrings.
- --skip-verify
- Skip the signature verification step. This may be used to
make the decryption faster if the signature verification is not needed.
- --with-key-data
- Print key listings delimited by colons (like
--with-colons) and print the public key data.
- --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. If you are missing some information, don't
use this option.
- --no-literal
- This is not for normal use. Use the source to see for what
it might be useful.
- --set-filesize
- This is not for normal use. Use the source to see for what
it might be useful.
- --show-session-key
- Display the session key used for one message. See
--override-session-key for the counterpart of this option.
- --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 set via
--default-sig-expire is used. --no-ask-sig-expire disables
this option.
- --default-sig-expire
- The default expiration time to use for signature
expiration. Valid values are "0" for no expiration, a number
followed by the letter d (for days), w (for weeks), m (for months), or y
(for years) (for example "2m" for two months, or "5y"
for five years), or an absolute date in the form YYYY-MM-DD. Defaults to
"0".
- --ask-cert-expire
- --no-ask-cert-expire
- When making a key signature, prompt for an expiration time.
If this option is not specified, the expiration time set via
--default-cert-expire is used. --no-ask-cert-expire disables
this option.
- --default-cert-expire
- The default expiration time to use for key signature
expiration. Valid values are "0" for no expiration, a number
followed by the letter d (for days), w (for weeks), m (for months), or y
(for years) (for example "2m" for two months, or "5y"
for five years), or an absolute date in the form YYYY-MM-DD. Defaults to
"0".
- --allow-secret-key-import
- This is an obsolete option and is not used anywhere.
- --allow-multiple-messages
- --no-allow-multiple-messages
- Allow processing of multiple OpenPGP messages contained in
a single file or stream. Some programs that call GPG are not prepared to
deal with multiple messages being processed together, so this option
defaults to no. Note that versions of GPG prior to 1.4.7 always allowed
multiple messages.
- --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.
- --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.
- --default-preference-list string
- Set the list of default preferences to string. This
preference list is used for new keys and becomes the default for
"setpref" in the edit menu.
- --default-keyserver-url name
- Set the default keyserver URL to name. This
keyserver will be used as the keyserver URL when writing a new
self-signature on a key, which includes key generation and changing
preferences.
- --list-config
- Display various internal configuration parameters of GnuPG.
This option is intended for external programs that call GnuPG to perform
tasks, and is thus not generally useful. See the file ‘
doc/DETAILS’ in the source distribution for the details of
which configuration items may be listed. --list-config is only
usable with --with-colons set.
- --gpgconf-list
- This command is similar to --list-config but in
general only internally used by the gpgconf tool.
- --gpgconf-test
- This is more or less dummy action. However it parses the
configuration file and returns with failure if the configuration file
would prevent gpg from startup. Thus it may be used to run a syntax
check on the configuration file.
Deprecated options¶
- --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.
- --show-photos
- --no-show-photos
- Causes --list-keys, --list-sigs,
--list-public-keys, --list-secret-keys, and verifying a
signature to also display the photo ID attached to the key, if any. See
also --photo-viewer. These options are deprecated. Use
--list-options [no-]show-photos and/or --verify-options
[no-]show-photos instead.
- --show-keyring
- Display the keyring name at the head of key listings to
show which keyring a given key resides on. This option is deprecated: use
--list-options [no-]show-keyring instead.
- --ctapi-driver file
- Use file to access the smartcard reader. The current
default is `libtowitoko.so'. Note that the use of this interface is
deprecated; it may be removed in future releases.
- --always-trust
- Identical to --trust-model always. This option is
deprecated.
- --show-notation
- --no-show-notation
- Show signature notations in the --list-sigs or
--check-sigs listings as well as when verifying a signature with a
notation in it. These options are deprecated. Use --list-options
[no-]show-notation and/or --verify-options [no-]show-notation
instead.
- --show-policy-url
- --no-show-policy-url
- Show policy URLs in the --list-sigs or
--check-sigs listings as well as when verifying a signature with a
policy URL in it. These options are deprecated. Use --list-options
[no-]show-policy-url and/or --verify-options
[no-]show-policy-url instead.
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 -u 0x12345678 -sb file
- make a detached signature with the key 0x12345678
- gpg --list-keys user_ID
- show keys
- gpg --fingerprint user_ID
- show fingerprint
- gpg --verify pgpfile
- gpg --verify sigfile
- Verify the signature of the file but do not output the
data. The second form is used for detached signatures, where
sigfile is the detached signature (either ASCII armored or binary)
and 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.
HOW TO SPECIFY A USER ID¶
There are different ways to specify a user ID to GnuPG. Some of them are only valid for gpg others are only good for gpgsm. Here is the entire list of ways to specify a key:- By key Id.
- This format is deduced from the length of the string and
its content or 0x prefix. The key Id of an X.509 certificate are
the low 64 bits of its SHA-1 fingerprint. The use of key Ids is just a
shortcut, for all automated processing the fingerprint should be used.
234567C4 0F34E556E 01347A56A 0xAB123456 234AABBCC34567C4 0F323456784E56EAB 01AB3FED1347A5612 0x234AABBCC34567C4
- By fingerprint.
- This format is deduced from the length of the string and
its content or the 0x prefix. Note, that only the 20 byte version
fingerprint is available with gpgsm (i.e. the SHA-1 hash of the
certificate).
1234343434343434C434343434343434 123434343434343C3434343434343734349A3434 0E12343434343434343434EAB3484343434343434 0xE12343434343434343434EAB3484343434343434
- By exact match on OpenPGP user ID.
- This is denoted by a leading equal sign. It does not make
sense for X.509 certificates.
=Heinrich Heine <heinrichh@uni-duesseldorf.de>
- By exact match on an email address.
- This is indicated by enclosing the email address in the
usual way with left and right angles.
<heinrichh@uni-duesseldorf.de>
- By word match.
- All words must match exactly (not case sensitive) but can
appear in any order in the user ID or a subjects name. Words are any
sequences of letters, digits, the underscore and all characters with bit 7
set.
+Heinrich Heine duesseldorf
- By exact match on the subject's DN.
- This is indicated by a leading slash, directly followed by
the RFC-2253 encoded DN of the subject. Note that you can't use the string
printed by "gpgsm --list-keys" because that one as been
reordered and modified for better readability; use --with-colons to print
the raw (but standard escaped) RFC-2253 string
/CN=Heinrich Heine,O=Poets,L=Paris,C=FR
- By exact match on the issuer's DN.
- This is indicated by a leading hash mark, directly followed
by a slash and then directly followed by the rfc2253 encoded DN of the
issuer. This should return the Root cert of the issuer. See note above.
#/CN=Root Cert,O=Poets,L=Paris,C=FR
- By exact match on serial number and issuer's DN.
- This is indicated by a hash mark, followed by the
hexadecimal representation of the serial number, then followed by a slash
and the RFC-2253 encoded DN of the issuer. See note above.
#4F03/CN=Root Cert,O=Poets,L=Paris,C=FR
- By keygrip
- This is indicated by an ampersand followed by the 40 hex
digits of a keygrip. gpgsm prints the keygrip when using the
command --dump-cert. It does not yet work for OpenPGP keys.
&D75F22C3F86E355877348498CDC92BD21010A480
- By substring match.
- This is the default mode but applications may want to
explicitly indicate this by putting the asterisk in front. Match is not
case sensitive.
Heine *Heine
FILES¶
There are a few configuration files to control certain aspects of gpg's operation. Unless noted, they are expected in the current home directory (see: [option --homedir]).- gpg.conf
- This is the standard configuration file read by gpg
on startup. It may contain any valid long option; the leading two dashes
may not be entered and the option may not be abbreviated. This default
name may be changed on the command line (see: [option --options]). You
should backup this file.
- ~/.gnupg/secring.gpg
- The secret keyring. You should backup this file.
- ~/.gnupg/secring.gpg.lock
- The lock file for the secret keyring.
- ~/.gnupg/pubring.gpg
- The public keyring. You should backup this file.
- ~/.gnupg/pubring.gpg.lock
- The lock file for the public keyring.
- ~/.gnupg/trustdb.gpg
- The trust database. There is no need to backup this file;
it is better to backup the ownertrust values (see: [option
--export-ownertrust]).
- ~/.gnupg/trustdb.gpg.lock
- The lock file for the trust database.
- ~/.gnupg/random_seed
- A file used to preserve the state of the internal random
pool.
- /usr[/local]/share/gnupg/options.skel
- The skeleton options file.
- /usr[/local]/lib/gnupg/
- Default location for extensions.
- 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. This is 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.
- PINENTRY_USER_DATA
- This value is passed via gpg-agent to pinentry. It is
useful to convey extra information to a custom pinentry.
- COLUMNS
- LINES
- Used to size some displays to the full size of the screen.
- LANGUAGE
- Apart from its use by GNU, it is used in the W32 version to
override the language selection done through the Registry. If used and set
to a valid and available language name ( langid), the file with the
translation is loaded from
BUGS¶
On older systems this program should be installed as setuid(root). This is necessary to lock memory pages. Locking memory pages prevents the operating system from writing memory pages (which may contain passphrases or other sensitive material) to disk. If you get no warning message about insecure memory your operating system supports locking without being root. The program drops root privileges as soon as locked memory is allocated.SEE ALSO¶
gpgv(1),info gnupg
2015-03-08 | GnuPG 1.4.12 |