\input texinfo @c This Texinfo document has been automatically generated by @c docbook2texi from a DocBook documentation. The tool used @c can be found at: @c @c Please send any bug reports, improvements, comments, @c patches, etc. to Steve Cheng . @setfilename gpg.info @node top @top gpg @menu @end menu @majorheading Name gpg ---- encryption and signing tool @majorheading Synopsis @majorheading DESCRIPTION @code{gpg} is the main program for the GnuPG system. This man page only lists the commands and options available. For a more verbose documentation get the GNU Privacy Handbook (GPH), which is available at http://www.gnupg.org/gph/ . You will find a list of HOWTO documents at http://www.gnupg.org/docs.html . Please remember that option parsing stops as soon as a non option is encountered, you can explicitly stop option parsing by using the special option "---". @majorheading COMMANDS @code{gpg} recognizes these commands: @table @asis @item -s, ---sign Make a signature. This command may be combined with ---encrypt. @item ---clearsign Make a clear text signature. @item -b, ---detach-sign Make a detached signature. @item -e, ---encrypt Encrypt data. This option may be combined with ---sign. @item -c, ---symmetric Encrypt with symmetric cipher only. This command asks for a passphrase. @item ---store Store only (make a simple RFC1991 packet). @item ---decrypt @code{file} Decrypt @code{file} (or stdin if no file is specified) and write it to stdout (or the file specified with ---output). If the decrypted file is signed, the signature is also verified. This command differs from the default operation, as it never writes to the filename which is included in the file and it rejects files which don't begin with an encrypted message. @item ---verify @code{sigfile} @code{signed-files} Assume that @code{sigfile} is a signature and verify it without generating any output. With no arguments, the signature packet is read from stdin. If only a sigfile is given, it may be a complete signature or a detached signature, in which case the signed stuff is expected in a file without the ".sig" or ".asc" extension. With more than 1 argument, the first should be a detached signature and the remaining files are the signed stuff. To read the signed stuff from stdin, use @samp{-} as the second filename. For security reasons a detached signature cannot read the signed material from stdin without denoting it in the above way. @item ---verify-files @code{files} This is a special version of the ---verify command which does not work with detached signatures. The command expects the files to be verified either on the command line or reads the filenames from stdin; each name must be on separate line. The command is intended for quick checking of many files. @item ---list-keys @code{names} @itemx ---list-public-keys @code{names} List all keys from the public keyrings, or just the ones given on the command line. @item ---list-secret-keys @code{names} List all keys from the secret keyrings, or just the ones given on the command line. @item ---list-sigs @code{names} Same as ---list-keys, but the signatures are listed too. @item ---check-sigs @code{names} Same as ---list-sigs, but the signatures are verified. @item ---fingerprint @code{names} List all keys with their fingerprints. This is the same output as ---list-keys but with the additional output of a line with the fingerprint. May also be combined with ---list-sigs or --check-sigs. If this command is given twice, the fingerprints of all secondary keys are listed too. @item ---list-packets List only the sequence of packets. This is mainly useful for debugging. @item ---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 @file{doc/DETAILS} in the source distribution on how to use this. @item ---edit-key @code{name} Present a menu which enables you to do all key related tasks: @table @asis @item sign Make a signature on key of user @code{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. @item 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. @item revsig Revoke a signature. GnuPG asks for every signature which has been done by one of the secret keys, whether a revocation certificate should be generated. @item trust Change the owner trust value. This updates the trust-db immediately and no save is required. @item disable @itemx enable Disable or enable an entire key. A disabled key can normally not be used for encryption. @item adduid Create an alternate user id. @item deluid Delete a user id. @item addkey Add a subkey to this key. @item delkey Remove a subkey. @item revkey Revoke a subkey. @item expire Change the key expiration time. If a key is selected, the time of this key will be changed. With no selection the key expiration of the primary key is changed. @item passwd Change the passphrase of the secret key. @item 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. @item uid @code{n} Toggle selection of user id with index @code{n}. Use 0 to deselect all. @item key @code{n} Toggle selection of subkey with index @code{n}. Use 0 to deselect all. @item check Check all selected user ids. @item pref List preferences. @item showpref More verbose preferences listing. @item setpref @code{string} Set the list of user ID preferences to @code{string}, this should be a string similar to the one printed by "pref". Using an empty string will set the default preference string, using "none" will set the preferences to nil. Only available algorithms are allowed. This command just initializes an internal list and does not change anything unless another command which changes the self-signatures is used. @item updpref Change the preferences of all user IDs (or just of the selected ones to the current list of preferences. The timestamp of all affected self-signatures fill be advanced by one second. @item toggle Toggle between public and secret key listing. @item save Save all changes to the key rings and quit. @item quit Quit the program without updating the key rings. @end table The listing shows you the key with its secondary keys and all user ids. Selected keys or user ids are indicated by an asterisk. The trust value is displayed with the primary key: the first is the assigned owner trust and the second is the calculated trust value. Letters are used for the values: @table @asis @item - No ownertrust assigned / not yet calculated. @item e Trust calculation has failed; probably due to an expired key. @item q Not enough information for calculation. @item n Never trust this key. @item m Marginally trusted. @item f Fully trusted. @item u Ultimately trusted. @end table @item ---sign-key @code{name} Sign a public key with your secret key. This is a shortcut version of the subcommand "sign" from ---edit. @item ---lsign-key @code{name} Sign a public key with your secret key but mark it as non-exportable. This is a shortcut version of the subcommand "lsign" from ---edit. @item ---trusted-key @code{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. @item ---delete-key @code{name} Remove key from the public keyring @item ---delete-secret-key @code{name} Remove key from the secret and public keyring @item ---delete-secret-and-public-key @code{name} Same as ---delete-key, but if a secret key exists, it will be removed first. @item ---gen-revoke Generate a revocation certificate for the complete key. To revoke a subkey or a signature, use the ---edit command. @item ---export @code{names} Either export all keys from all keyrings (default keyrings and those registered via option ---keyring), or if at least one name is given, those of the given name. The new keyring is written to stdout or to the file given with option "output". Use together with ---armor to mail those keys. @item ---send-keys @code{names} Same as ---export but sends the keys to a keyserver. Option ---keyserver must be used to give the name of this keyserver. Don't send your complete keyring to a keyserver - select only those keys which are new or changed by you. @item ---export-all @code{names} Same as ---export, but also exports keys which are not compatible with OpenPGP. @item ---export-secret-keys @code{names} @itemx ---export-secret-subkeys @code{names} Same as ---export, but exports the secret keys instead. This is normally not very useful and a security risk. The second form of the command has the special property to render the secret part of the primary key useless; this is a GNU extension to OpenPGP and other implementations can not be expected to successfully import such a key. @item ---import @code{files} @itemx ---fast-import @code{files} Import/merge keys. This adds the given keys to the keyring. The fast version does not update the trustdb; this can be done at any time with the command ---update-trustdb. There are a few other options which control how this command works. Most notable here is the ---merge-only option which does not insert new keys but does only the merging of new signatures, user-IDs and subkeys. @item ---recv-keys @code{key IDs} Import the keys with the given key IDs from a HKP keyserver. Option ---keyserver must be used to give the name of this keyserver. @item ---recv-keys @code{key IDs} Import the keys with the given key IDs from a HKP keyserver. Option ---keyserver must be used to give the name of this keyserver. @item ---update-trustdb Do trust DB maintenance. This command goes over all keys and builds the Web-of-Trust. This is an intercative command because it may has to ask for the "ownertrust" values of keys. The user has to give an estimation in how far she trusts the owner of the displayed key to correctly certify (sign) other keys. It does only ask for that value if it has not yet been assigned to a key. Using the edit menu, that value can be changed at any time later. @item ---check-trustdb Do trust DB maintenance without user interaction. Form time to time the trust database must be updated so that expired keys and resulting changes in the Web-of_trust can be tracked. GnuPG tries to figure when this is required and then does it implicitly; this command can be used to force such a check. The processing is identically to that of ---update-trustdb but it skips keys with a not yet defined "ownertrust". @item ---import-ownertrust @code{files} Update the trustdb with the ownertrust values stored in @code{files} (or stdin if not given); existing values will be overwritten. @item ---print-md @code{algo} @code{files} @itemx ---print-mds @code{files} Print message digest of algorithm ALGO for all given files or stdin. With the second form (or a deprecated "*" as algo) digests for all available algorithms are printed. @item ---gen-random @code{0|1|2} @code{count} Emit COUNT random bytes of the given quality level. If count is not given or zero, an endless sequence of random bytes will be emitted. PLEASE, don't use this command unless you know what you are doing; it may remove precious entropy from the system! @item ---gen-prime @code{mode} @code{bits} @code{qbits} Use the source, Luke :-). The output format is still subject to change. @item ---version Print version information along with a list of supported algorithms. @item ---warranty Print warranty information. @item -h, ---help Print usage information. This is a really long list even though it doesn't list all options. @end table @majorheading OPTIONS Long options can be put in an options file (default "~/.gnupg/options"). Do not write the 2 dashes, but simply the name of the option and any required arguments. Lines with a hash as the first non-white-space character are ignored. Commands may be put in this file too, but that does not make sense. @code{gpg} recognizes these options: @table @asis @item -a, ---armor Create ASCII armored output. @item -o, ---output @code{file} Write output to @code{file}. @item -u, ---local-user @code{name} Use @code{name} as the user ID to sign. This option is silently ignored for the list commands, so that it can be used in an options file. @item ---default-key @code{name} Use @code{name} as default user ID for signatures. If this is not used the default user ID is the first user ID found in the secret keyring. @item -r, ---recipient @code{name} @itemx Encrypt for user id @code{name}. If this option is not specified, GnuPG asks for the user-id unless ---default-recipient is given @item ---default-recipient @code{name} Use @code{name} as default recipient if option ---recipient is not used and don't ask if this is a valid one. @code{name} must be non-empty. @item ---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. @item ---no-default-recipient Reset ---default-recipient and --default-recipient-self. @item ---encrypt-to @code{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. @item ---no-encrypt-to Disable the use of all ---encrypt-to keys. @item -v, ---verbose Give more information during processing. If used twice, the input data is listed in detail. @item -q, ---quiet Try to be as quiet as possible. @item -z @code{n} Set compression level to @code{n}. A value of 0 for @code{n} disables compression. Default is to use the default compression level of zlib (normally 6). @item -t, ---textmode Use canonical text mode. If -t (but not ---textmode) is used together with armoring and signing, this enables clearsigned messages. This kludge is needed for PGP compatibility; normally you would use ---sign or --clearsign to selected the type of the signature. @item -n, ---dry-run Don't make any changes (this is not completely implemented). @item -i, ---interactive Prompt before overwriting any files. @item ---batch Use batch mode. Never ask, do not allow interactive commands. @item ---no-tty Make sure that the TTY (terminal) is never used for any output. This option is needed in some cases because GnuPG sometimes prints warnings to the TTY if ---batch is used. @item ---no-batch Disable batch mode. This may be of use if ---batch is enabled from an options file. @item ---yes Assume "yes" on most questions. @item ---no Assume "no" on most questions. @item ---always-trust Skip key validation and assume that used keys are always fully trusted. You won't use this unless you have installed some external validation scheme. This option also suppresses the "[uncertain]" tag printed with signature checks when there is no evidence that the user ID is bound to the key. @item ---keyserver @code{name} Use @code{name} to lookup keys which are not yet in your keyring. This is only done while verifying messages with signatures. The option is also required for the command ---send-keys to specify the keyserver to where the keys should be send. All keyservers synchronize with each other - so there is no need to send keys to more than one server. Using the command "host -l pgp.net | grep wwwkeys" gives you a list of keyservers. Because there is load balancing using round-robin DNS you may notice that you get different key servers. @item ---no-auto-key-retrieve This option disables the automatic retrieving of keys from a keyserver while verifying signatures. This option allows you to keep a keyserver in the options file for the ---send-keys and --recv-keys commands. @item ---honor-http-proxy Try to access the keyserver over the proxy set with the variable "http_proxy". @item ---keyring @code{file} Add @code{file} to the list of keyrings. If @code{file} begins with a tilde and a slash, these are replaced by the HOME directory. If the filename does not contain a slash, it is assumed to be in the home-directory ("~/.gnupg" if ---homedir is not used). The filename may be prefixed with a scheme: "gnupg-ring:" is the default one. It might make sense to use it together with ---no-default-keyring. @item ---secret-keyring @code{file} Same as ---keyring but for the secret keyrings. @item ---homedir @code{directory} Set the name of the home directory to @code{directory} If this option is not used it defaults to "~/.gnupg". It does not make sense to use this in a options file. This also overrides the environment variable "GNUPGHOME". @item ---charset @code{name} Set the name of the native character set. This is used to convert some strings to proper UTF-8 encoding. Valid values for @code{name} are: @table @asis @item iso-8859-1 This is the default Latin 1 set. @item iso-8859-2 The Latin 2 set. @item koi8-r The usual Russian set (rfc1489). @item utf-8 Bypass all translations and assume that the OS uses native UTF-8 encoding. @end table @item ---utf8-strings @itemx ---no-utf8-strings Assume that the arguments are already given as UTF8 strings. The default (---no-utf8-strings) is to assume that arguments are encoded in the character set as specified by ---charset. These options affect all following arguments. Both options may be used multiple times. @item ---options @code{file} Read options from @code{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. @item ---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. @item ---load-extension @code{name} Load an extension module. If @code{name} does not contain a slash it is searched in "/usr/local/lib/gnupg" See the manual for more information about extensions. @item ---debug @code{flags} Set debugging flags. All flags are or-ed and @code{flags} may be given in C syntax (e.g. 0x0042). @item ---debug-all Set all useful debugging flags. @item ---status-fd @code{n} Write special status strings to the file descriptor @code{n}. See the file DETAILS in the documentation for a listing of them. @item ---logger-fd @code{n} Write log output to file descriptor @code{n} and not to stderr. @item ---no-comment Do not write comment packets. This option affects only the generation of secret keys. Please note, that this has nothing to do with the comments in clear text signatures. @item ---comment @code{string} Use @code{string} as comment string in clear text signatures. The default is not do write a comment string. @item ---default-comment Force to write the standard comment string in clear text signatures. Use this to overwrite a ---comment from a config file. This option is now obsolete because there is no default comment string anymore. @item ---no-version Omit the version string in clear text signatures. @item ---emit-version Force to write the version string in clear text signatures. Use this to overwrite a previous ---no-version from a config file. @item -N, ---notation-data @code{name=value} Put the name value pair into the signature as notation data. @code{name} must consist only of alphanumeric characters, digits or the underscore; the first character must not be a digit. @code{value} may be any printable string; it will be encoded in UTF8, so you should check that your ---charset is set correctly. If you prefix @code{name} with an exclamation mark, the notation data will be flagged as critical (rfc2440:5.2.3.15). @item ---set-policy-url @code{string} Use @code{string} as Policy URL for signatures (rfc2440:5.2.3.19). If you prefix it with an exclamation mark, the policy URL packet will be flagged as critical. @item ---set-filename @code{string} Use @code{string} as the name of file which is stored in messages. @item ---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. @item ---completes-needed @code{n} Number of completely trusted users to introduce a new key signer (defaults to 1). @item ---marginals-needed @code{n} Number of marginally trusted users to introduce a new key signer (defaults to 3) @item ---max-cert-depth @code{n} Maximum depth of a certification chain (default is 5). @item ---cipher-algo @code{name} Use @code{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. @item ---digest-algo @code{name} Use @code{name} as message digest algorithm. Running the program with the command ---version yields a list of supported algorithms. Please note that using this option may violate the OpenPGP requirement, that a 160 bit hash is to be used for DSA. @item ---s2k-cipher-algo @code{name} Use @code{name} as the cipher algorithm used to protect secret keys. The default cipher is BLOWFISH. This cipher is also used for conventional encryption if ---cipher-algo is not given. @item ---s2k-digest-algo @code{name} Use @code{name} as the digest algorithm used to mangle the passphrases. The default algorithm is RIPE-MD-160. This digest algorithm is also used for conventional encryption if ---digest-algo is not given. @item ---s2k-mode @code{n} Selects how passphrases are mangled. If @code{n} is 0 a plain passphrase (which is not recommended) will be used, a 1 (default) adds a salt to the passphrase and a 3 iterates the whole process a couple of times. Unless ---rfc1991 is used, this mode is also used for conventional encryption. @item ---compress-algo @code{n} Use compress algorithm @code{n}. Default is 2 which is RFC1950 compression. You may use 1 to use the old zlib version (RFC1951) which is used by PGP. The default algorithm may give better results because the window size is not limited to 8K. If this is not used the OpenPGP behavior is used, i.e. the compression algorithm is selected from the preferences; note, that this can't be done if you do not encrypt the data. @item ---disable-cipher-algo @code{name} Never allow the use of @code{name} as cipher algorithm. The given name will not be checked so that a later loaded algorithm will still get disabled. @item ---disable-pubkey-algo @code{name} Never allow the use of @code{name} as public key algorithm. The given name will not be checked so that a later loaded algorithm will still get disabled. @item ---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. @item ---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. @item ---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. As this is a time consuming process, this option allow to disable the automatic invocation. @item ---throw-keyid Do not put the keyid into encrypted packets. This option hides the receiver of the message and is a countermeasure against traffic analysis. It may slow down the decryption process because all available secret keys are tried. @item ---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. @item ---escape-from-lines Because some mailers change lines starting with "From " to " Using an exact to match string. The equal sign indicates this. @item Using the email address part which must match exactly. The left angle bracket indicates this email address mode. @item +Heinrich Heine duesseldorf All words must match exactly (not case sensitive) but can appear in any order in the user ID. Words are any sequences of letters, digits, the underscore and all characters with bit 7 set. @item #34 Using the Local ID. This is a very low level method and should only be used by applications which really need it. The hash character indicates this method. An application should not assume that this is only a number. @item Heine @itemx *Heine By case insensitive substring matching. This is the default mode but applications may want to explicitly indicate this by putting the asterisk in front. @end table Note that you can append an exclamation mark to key IDs or fingerprints. This flag which tells GnuPG to use exactly that primary or secondary key and don't try to figure out which secondary or primary key to use. @majorheading 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. @majorheading EXAMPLES @table @asis @item gpg -se -r @code{Bob} @code{file} sign and encrypt for user Bob @item gpg ---clearsign @code{file} make a clear text signature @item gpg -sb @code{file} make a detached signature @item gpg ---list-keys @code{user_ID} show keys @item gpg ---fingerprint @code{user_ID} show fingerprint @item gpg ---verify @code{pgpfile} @itemx gpg ---verify @code{sigfile} @code{files} Verify the signature of the file but do not output the data. The second form is used for detached signatures, where @code{sigfile} is the detached signature (either ASCII armored of binary) and @code{files} are the signed data; if this is not given the name of the file holding the signed data is constructed by cutting off the extension (".asc" or ".sig") of @code{sigfile} or by asking the user for the filename. @end table @majorheading ENVIRONMENT @table @asis @item HOME Used to locate the default home directory. @item GNUPGHOME If set directory used instead of "~/.gnupg". @item http_proxy Only honored when the option ---honor-http-proxy is set. @end table @majorheading FILES @table @asis @item ~/.gnupg/secring.gpg The secret keyring @item ~/.gnupg/secring.gpg.lock and the lock file @item ~/.gnupg/pubring.gpg The public keyring @item ~/.gnupg/pubring.gpg.lock and the lock file @item ~/.gnupg/trustdb.gpg The trust database @item ~/.gnupg/trustdb.gpg.lock and the lock file @item ~/.gnupg/random_seed used to preserve the internal random pool @item ~/.gnupg/options May contain options @item /usr[/local]/share/gnupg/options.skel Skeleton options file @item /usr[/local]/lib/gnupg/ Default location for extensions @end table @majorheading WARNINGS Use a *good* password for your user account and a *good* passphrase to protect your secret key. This passphrase is the weakest part of the whole system. Programs to do dictionary attacks on your secret keyring are very easy to write and so you should protect your "~/.gnupg/" directory very well. Keep in mind that, if this program is used over a network (telnet), it is *very* easy to spy out your passphrase! If you are going to verify detached signatures, make sure that the program knows about it; either be giving both filenames on the commandline or using @samp{-} to specify stdin. @majorheading BUGS On many systems this program should be installed as setuid(root). This is necessary to lock memory pages. Locking memory pages prevents the operating system from writing memory pages to disk. If you get no warning message about insecure memory your operating system supports locking without being root. The program drops root privileges as soon as locked memory is allocated. @bye