@c Copyright (C) 2002 Free Software Foundation, Inc. @c This is part of the GnuPG manual. @c For copying conditions, see the file gnupg.texi. @node Invoking GPGSM @chapter Invoking GPGSM @cindex GPGSM command options @cindex command options @cindex options, GPGSM command @manpage gpgsm.1 @ifset manverb .B gpgsm \- CMS encryption and signing tool @end ifset @mansect synopsis @ifset manverb .B gpgsm .RB [ \-\-homedir .IR dir ] .RB [ \-\-options .IR file ] .RI [ options ] .I command .RI [ args ] @end ifset @mansect description @command{gpgsm} is a tool similar to @command{gpg} to provide digital encryption and signing servicesd on X.509 certificates and the CMS protocol. It is mainly used as a backend for S/MIME mail processing. @command{gpgsm} includes a full features certificate management and complies with all rules defined for the German Sphinx project. @manpause @xref{Option Index}, for an index to @command{GPGSM}'s commands and options. @mancont @menu * GPGSM Commands:: List of all commands. * GPGSM Options:: List of all options. * GPGSM Configuration:: Configuration files. * GPGSM Examples:: Some usage examples. Developer information: * Unattended Usage:: Using @command{gpgsm} from other programs. * GPGSM Protocol:: The protocol the server mode uses. @end menu @c ******************************************* @c *************** **************** @c *************** COMMANDS **************** @c *************** **************** @c ******************************************* @mansect commands @node GPGSM Commands @section Commands Commands are not distinguished from options except for the fact that only one command is allowed. @menu * General GPGSM Commands:: Commands not specific to the functionality. * Operational GPGSM Commands:: Commands to select the type of operation. * Certificate Management:: How to manage certificates. @end menu @c ******************************************* @c ********** GENERAL COMMANDS ************* @c ******************************************* @node General GPGSM Commands @subsection Commands not specific to the function @table @gnupgtabopt @item --version @opindex version Print the program version and licensing information. Not that you can abbreviate this command. @item --help, -h @opindex help Print a usage message summarizing the most usefule command-line options. Not that you can abbreviate this command. @item --warranty @opindex warranty Print warranty information. @item --dump-options @opindex dump-options Print a list of all available options and commands. Not that you can abbreviate this command. @end table @c ******************************************* @c ******** OPERATIONAL COMMANDS *********** @c ******************************************* @node Operational GPGSM Commands @subsection Commands to select the type of operation @table @gnupgtabopt @item --encrypt @opindex encrypt Perform an encryption. The keys the data is encrypted too must be set using the option @option{--recipient}. @item --decrypt @opindex decrypt Perform a decryption; the type of input is automatically determined. It may either be in binary form or PEM encoded; automatic determination of base-64 encoding is not done. @item --sign @opindex sign Create a digital signature. The key used is either the fist one found in the keybox or those set with the @option{--local-user} option. @item --verify @opindex verify Check a signature file for validity. Depending on the arguments a detached signatrue may also be checked. @item --server @opindex server Run in server mode and wait for commands on the @code{stdin}. @item --call-dirmngr @var{command} [@var{args}] @opindex call-dirmngr Behave as a Dirmngr client issuing the request @var{command} with the optional list of @var{args}. The output of the Dirmngr is printed stdout. Please note that file names given as arguments should have an absulte file name (i.e. commencing with @code{/} because they are passed verbatim to the Dirmngr and the working directory of the Dirmngr might not be the same as the one of this client. Currently it is not possible to pass data via stdin to the Dirmngr. @var{command} should not contain spaces. This is command is required for certain maintaining tasks of the dirmngr where a dirmngr must be able to call back to @command{gpgsm}. See the Dirmngr manual for details. @item --call-protect-tool @var{arguments} @opindex call-protect-tool Certain maintenance operations are done by an external program call @command{gpg-protect-tool}; this is usually not installed in a directory listed in the PATH variable. This command provides a simple wrapper to access this tool. @var{arguments} are passed verbatim to this command; use @samp{--help} to get a list of supported operations. @end table @c ******************************************* @c ******* CERTIFICATE MANAGEMENT ********** @c ******************************************* @node Certificate Management @subsection How to manage the certificates and keys @table @gnupgtabopt @item --gen-key @opindex gen-key This command allows the interactive creation of a certifcate signing request. It is commonly used along with the @option{--output} option to save the created CSR into a file. @item --list-keys @itemx -k @opindex list-keys List all available certificates stored in the local key database. Note that the displayed data might be reformatted for better human readability and illegal characters are replaced by safe substitutes. @item --list-secret-keys @itemx -K @opindex list-secret-keys List all available certificates for which a corresponding a secret key is available. @item --list-external-keys @var{pattern} @opindex list-keys List certificates matching @var{pattern} using an external server. This utilizes the @code{dirmngr} service. @item --list-chain @opindex list-chain Same as @option{--list-keys} but also prints all keys making up the chain. @item --dump-cert @itemx --dump-keys @opindex dump-cert @opindex dump-keys List all available certificates stored in the local key database using a format useful mainly for debugging. @item --dump-chain @opindex dump-chain Same as @option{--dump-keys} but also prints all keys making up the chain. @item --dump-secret-keys @opindex dump-secret-keys List all available certificates for which a corresponding a secret key is available using a format useful mainly for debugging. @item --dump-external-keys @var{pattern} @opindex dump-external-keys List certificates matching @var{pattern} using an external server. This utilizes the @code{dirmngr} service. It uses a format useful mainly for debugging. @item --keydb-clear-some-cert-flags @opindex keydb-clear-some-cert-flags This is a debugging aid to reset certain flags in the key database which are used to cache certain certificate stati. It is especially useful if a bad CRL or a weird running OCSP reponder did accidently revoke certificate. There is no security issue with this command because @command{gpgsm} always make sure that the validity of a certificate is checked right before it is used. @item --delete-keys @var{pattern} @opindex delete-keys Delete the keys matching @var{pattern}. @item --export [@var{pattern}] @opindex export Export all certificates stored in the Keybox or those specified by the optional @var{pattern}. Those pattern consist of a list of user ids (@pxref{how-to-specify-a-user-id}). When used along with the @option{--armor} option a few informational lines are prepended before each block. There is one limitation: As there is no commonly agreed upon way to pack more than one certificate into an ASN.1 structure, the binary export (i.e. without using @option{armor}) works only for the export of one certificate. Thus it is required to specify a @var{pattern} which yields exactly one certificate. @item --export-secret-key-p12 @var{key-id} @opindex export Export the private key and the certificate identified by @var{key-id} in a PKCS#12 format. When using along with the @code{--armor} option a few informational lines are prepended to the output. Note, that the PKCS#12 format is not very secure and this command is only provided if there is no other way to exchange the private key. (@pxref{option --p12-charset}) @item --import [@var{files}] @opindex import Import the certificates from the PEM or binary encoded files as well as from signed-only messages. This command may also be used to import a secret key from a PKCS#12 file. @item --learn-card @opindex learn-card Read information about the private keys from the smartcard and import the certificates from there. This command utilizes the @command{gpg-agent} and in turn the @command{scdaemon}. @item --passwd @var{user_id} @opindex passwd Change the passphrase of the private key belonging to the certificate specified as @var{user_id}. Note, that changing the passphrase/PIN of a smartcard is not yet supported. @end table @c ******************************************* @c *************** **************** @c *************** OPTIONS **************** @c *************** **************** @c ******************************************* @mansect options @node GPGSM Options @section Option Summary @command{GPGSM} comes features a bunch ofoptions to control the exact behaviour and to change the default configuration. @menu * Configuration Options:: How to change the configuration. * Certificate Options:: Certificate related options. * Input and Output:: Input and Output. * CMS Options:: How to change how the CMS is created. * Esoteric Options:: Doing things one usually don't want to do. @end menu @c ******************************************* @c ******** CONFIGURATION OPTIONS ********** @c ******************************************* @node Configuration Options @subsection How to change the configuration These options are used to change the configuraton and are usually found in the option file. @table @gnupgtabopt @item --options @var{file} @opindex options Reads configuration from @var{file} instead of from the default per-user configuration file. The default configuration file is named @file{gpgsm.conf} and expected in the @file{.gnupg} directory directly below the home directory of the user. @include opt-homedir.texi @item -v @item --verbose @opindex v @opindex verbose Outputs additional information while running. You can increase the verbosity by giving several verbose commands to @command{gpgsm}, such as @samp{-vv}. @item --policy-file @var{filename} @opindex policy-file Change the default name of the policy file to @var{filename}. @item --agent-program @var{file} @opindex agent-program Specify an agent program to be used for secret key operations. The default value is the @file{/usr/local/bin/gpg-agent}. This is only used as a fallback when the envrionment variable @code{GPG_AGENT_INFO} is not set or a running agent can't be connected. @item --dirmngr-program @var{file} @opindex dirmnr-program Specify a dirmngr program to be used for @acronym{CRL} checks. The default value is @file{/usr/sbin/dirmngr}. This is only used as a fallback when the environment variable @code{DIRMNGR_INFO} is not set or a running dirmngr can't be connected. @item --prefer-system-dirmngr @opindex prefer-system-dirmngr If a system wide @command{dirmngr} is running in daemon mode, first try to connect to this one. Fallback to a pipe based server if this does not work. Under Windows this option is ignored because the system dirmngr is always used. @item --disable-dirmngr Entirely disable the use of the Dirmngr. @item --no-secmem-warning @opindex no-secmem-warning Don't print a warning when the so called "secure memory" can't be used. @item --log-file @var{file} @opindex log-file When running in server mode, append all logging output to @var{file}. @end table @c ******************************************* @c ******** CERTIFICATE OPTIONS ************ @c ******************************************* @node Certificate Options @subsection Certificate related options @table @gnupgtabopt @item --enable-policy-checks @itemx --disable-policy-checks @opindex enable-policy-checks @opindex disable-policy-checks By default policy checks are enabled. These options may be used to change it. @item --enable-crl-checks @itemx --disable-crl-checks @opindex enable-crl-checks @opindex disable-crl-checks By default the @acronym{CRL} checks are enabled and the DirMngr is used to check for revoked certificates. The disable option is most useful with an off-line network connection to suppress this check. @item --enable-trusted-cert-crl-check @itemx --disable-trusted-cert-crl-check @opindex enable-trusted-cert-crl-check @opindex disable-trusted-cert-crl-check By default the @acronym{CRL} for trusted root certificates are checked like for any other certificates. This allows a CA to revoke its own certificates voluntary without the need of putting all ever issued certificates into a CRL. The disable option may be used to switch this extra check off. Due to the caching done by the Dirmngr, there won't be any noticeable performance gain. Note, that this also disables possible OCSP checks for trusted root certificates. A more specific way of disabling this check is by adding the ``relax'' keyword to the root CA line of the @file{trustlist.txt} @item --force-crl-refresh @opindex force-crl-refresh Tell the dirmngr to reload the CRL for each request. For better performance, the dirmngr will actually optimize this by suppressing the loading for short time intervalls (e.g. 30 minutes). This option is useful to make sure that a fresh CRL is available for certificates hold in the keybox. The suggested way of doing this is by using it along with the option @option{--with-validation} for a key listing command. This option should not be used in a configuration file. @item --enable-ocsp @itemx --disable-ocsp @opindex enable-ocsp @opindex disable-ocsp Be default @acronym{OCSP} checks are disabled. The enable option may be used to enable OCSP checks via Dirmngr. If @acronym{CRL} checks are also enabled, CRLs will be used as a fallback if for some reason an OCSP request won't succeed. Note, that you have to allow OCSP requests in Dirmngr's configuration too (option @option{--allow-ocsp} and configure dirmngr properly. If you don't do so you will get the error code @samp{Not supported}. @item --auto-issuer-key-retrieve @opindex auto-issuer-key-retrieve If a required certificate is missing while validating the chain of certificates, try to load that certificate from an external location. This usually means that Dirmngr is employed t search for the certificate. Note that this option makes a "web bug" like behavior possible. LDAP server operators can see which keys you request, so by sending you a message signed by a brand new key (which you naturally will not have on your local keybox), the operator can tell both your IP address and the time when you verified the signature. @item --validation-model @var{name} @opindex validation-model This option changes the default validation model. The only possible values are "shell" (which is the default) and "chain" which forces the use of the chain model. The chain model is also used if an option in the @file{trustlist.txt} or an attribute of the certificate requests it. However the standard model (shell) is in that case always tried first. @end table @c ******************************************* @c *********** INPUT AND OUTPUT ************ @c ******************************************* @node Input and Output @subsection Input and Output @table @gnupgtabopt @item --armor @itemx -a @opindex armor @opindex -a Create PEM encoded output. Default is binary output. @item --base64 @opindex base64 Create Base-64 encoded output; i.e. PEM without the header lines. @item --assume-armor @opindex assume-armor Assume the input data is PEM encoded. Default is to autodetect the encoding but this is may fail. @item --assume-base64 @opindex assume-base64 Assume the input data is plain base-64 encoded. @item --assume-binary @opindex assume-binary Assume the input data is binary encoded. @anchor{option --p12-charset} @item --p12-charset @var{name} @opindex p12-charset @command{gpgsm} uses the UTF-8 encoding when encoding passphrases for PKCS#12 files. This option may be used to force the passphrase to be encoded in the specified encoding @var{name}. This is useful if the application used to import the key uses a different encoding and thus won't be able to import a file generated by @command{gpgsm}. Commonly used values for @var{name} are @code{Latin1} and @code{CP850}. Note that @command{gpgsm} itself automagically imports any file with a passphrase encoded to the most commonly used encodings. @item --default-key @var{user_id} @opindex default-key Use @var{user_id} as the standard key for signing. This key is used if no other key has been defined as a signing key. Note, that the first @option{--local-users} option also sets this key if it has not yet been set; however @option{--default-key} always overrides this. @item --local-user @var{user_id} @item -u @var{user_id} @opindex local-user @opindex -u Set the user(s) to be used for signing. The default is the first secret key found in the database. @item --recipient @var{name} @itemx -r @opindex recipient Encrypt to the user id @var{name}. There are several ways a user id may be given (@pxref{how-to-specify-a-user-id}). @item --output @var{file} @itemx -o @var{file} @opindex output Write output to @var{file}. The default is to write it to stdout. @item --with-key-data @opindex with-key-data Displays extra information with the @code{--list-keys} commands. Especially a line tagged @code{grp} is printed which tells you the keygrip of a key. This string is for example used as the file name of the secret key. @item --with-validation @opindex with-validation When doing a key listing, do a full validation check for each key and print the result. This is usually a slow operation because it requires a CRL lookup and other operations. When used along with --import, a validation of the certificate to import is done and only imported if it succeeds the test. Note that this does not affect an already available cwertificate in the DB. This option is therefore useful to simply verify a certificate. @item --with-md5-fingerprint For standard key listings, also print the MD5 fingerprint of the certificate. @end table @c ******************************************* @c ************* CMS OPTIONS *************** @c ******************************************* @node CMS Options @subsection How to change how the CMS is created. @table @gnupgtabopt @item --include-certs @var{n} @opindex include-certs Using @var{n} of -2 includes all certificate except for the root cert, -1 includes all certs, 0 does not include any certs, 1 includes only the signers cert (this is the default) and all other positive values include up to @var{n} certificates starting with the signer cert. @item --cipher-algo @var{oid} @opindex cipher-algo Use the cipher algorithm with the ASN.1 object identifier @var{oid} for encryption. For convenience the strings @code{3DES}, @code{AES} and @code{AES256} may be used instead of their OIDs. The default is @code{3DES} (1.2.840.113549.3.7). @end table @c ******************************************* @c ******** ESOTERIC OPTIONS *************** @c ******************************************* @node Esoteric Options @subsection Doing things one usually don't want to do. @table @gnupgtabopt @item --extra-digest-algo @var{name} @opindex extra-digest-algo Sometimes signatures are broken in that they announce a different digest algorithm than actually used. @command{gpgsm} uses a one-pass data processing model and thus needs to rely on the announcde digest algorithms to properly hash the data. As a workaround this option may be used to tell gpg to also hash the data using the algorithm @var{name}; this slows processing down a little bit but allows to verify such broken signatures. If @command{gpgsm} prints an error like ``digest algo 8 has not been enabled'' you may want to try this option, with @samp{SHA256} for @var{name}. @item --faked-system-time @var{epoch} @opindex faked-system-time This option is only useful for testing; it sets the system time back or forth to @var{epoch} which is the number of seconds elapsed since the year 1970. Alternativly @var{epoch} may be given as a full ISO time string (e.g. "20070924T154812"). @item --with-ephemeral-keys @opindex with-ephemeral-keys Include ephemeral flagged keys in the output of key listings. @item --debug-level @var{level} @opindex debug-level Select the debug level for investigating problems. @var{level} may be one of: @table @code @item none no debugging at all. @item basic some basic debug messages @item advanced more verbose debug messages @item expert even more detailed messages @item guru all of the debug messages you can get @end table How these messages are mapped to the actual debugging flags is not specified and may change with newer releases of this program. They are however carefully selected to best aid in debugging. @item --debug @var{flags} @opindex debug This option is only useful for debugging and the behaviour may change at any time without notice; using @code{--debug-levels} is the preferred method to select the debug verbosity. FLAGS are bit encoded and may be given in usual C-Syntax. The currently defined bits are: @table @code @item 0 (1) X.509 or OpenPGP protocol related data @item 1 (2) values of big number integers @item 2 (4) low level crypto operations @item 5 (32) memory allocation @item 6 (64) caching @item 7 (128) show memory statistics. @item 9 (512) write hashed data to files named @code{dbgmd-000*} @item 10 (1024) trace Assuan protocol @end table Note, that all flags set using this option may get overriden by @code{--debug-level}. @item --debug-all @opindex debug-all Same as @code{--debug=0xffffffff} @item --debug-allow-core-dump @opindex debug-allow-core-dump Usually @command{gpgsm} tries to avoid dumping core by well written code and by disabling core dumps for security reasons. However, bugs are pretty durable beasts and to squash them it is sometimes useful to have a core dump. This option enables core dumps unless the Bad Thing happened before the option parsing. @item --debug-no-chain-validation @opindex debug-no-chain-validation This is actually not a debugging option but only useful as such. It lets @command{gpgsm} bypass all certificate chain validation checks. @item --debug-ignore-expiration @opindex debug-ignore-expiration This is actually not a debugging option but only useful as such. It lets @command{gpgsm} ignore all notAfter dates, this is used by the regresssion tests. @item --fixed-passphrase @var{string} @opindex fixed-passphrase Supply the passphrase @var{string} to the gpg-protect-tool. This option is only useful for the regression tests included with this package and may be revised or removed at any time without notice. @item --no-common-certs-import @opindex no-common-certs-import Suppress the import of common certificates on keybox creation. @end table All the long options may also be given in the configuration file after stripping off the two leading dashes. @c ******************************************* @c *************** **************** @c *************** USER ID **************** @c *************** **************** @c ******************************************* @mansect how to specify a user id @ifset isman @include specify-user-id.texi @end ifset @c ******************************************* @c *************** **************** @c *************** FILES **************** @c *************** **************** @c ******************************************* @mansect files @node GPGSM Configuration @section Configuration files There are a few configuration files to control certain aspects of @command{gpgsm}'s operation. Unless noted, they are expected in the current home directory (@pxref{option --homedir}). @table @file @item gpgsm.conf @cindex gpgsm.conf This is the standard configuration file read by @command{gpgsm} 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 (@pxref{option --options}). @item policies.txt @cindex policies.txt This is a list of allowed CA policies. This file should list the object identifiers of the policies line by line. Empty lines and lines starting with a hash mark are ignored. Policies missing in this file and not marked as critical in the certificate will print only a warning; certificates with policies marked as critical and not listed in this file will fail the signature verification. For example, to allow only the policy 2.289.9.9, the file should look like this: @c man:.RS @example # Allowed policies 2.289.9.9 @end example @c man:.RE @item qualified.txt @cindex qualified.txt This is the list of root certificates used for qualified certificates. They are defined as certificates capable of creating legally binding signatures in the same way as handwritten signatures are. Comments start with a hash mark and empty lines are ignored. Lines do have a length limit but this is not a serious limitation as the format of the entries is fixed and checked by gpgsm: A non-comment line starts with optional whitespace, followed by exactly 40 hex character, white space and a lowercased 2 letter country code. Additional data delimited with by a white space is current ignored but might late be used for other purposes. Note that even if a certificate is listed in this file, this does not mean that the certificate is trusted; in general the certificates listed in this file need to be listed also in @file{trustlist.txt}. This is a global file an installed in the data directory (e.g. @file{/usr/share/gnupg/qualified.txt}). GnuPG installs a suitable file with root certificates as used in Germany. As new Root-CA certificates may be issued over time, these entries may need to be updated; new distributions of this software should come with an updated list but it is still the responsibility of the Administrator to check that this list is correct. Everytime @command{gpgsm} uses a certificate for signing or verification this file will be consulted to check whether the certificate under question has ultimately been issued by one of these CAs. If this is the case the user will be informed that the verified signature represents a legally binding (``qualified'') signature. When creating a signature using such a certificate an extra prompt will be issued to let the user confirm that such a legally binding signature shall really be created. Because this software has not yet been approved for use with such certificates, appropriate notices will be shown to indicate this fact. @item help.txt @cindex help.txt This is plain text file with a few help entries used with @command{pinentry} as well as a large list of help items for @command{gpg} and @command{gpgsm}. The standard file has English help texts; to install localized versions use filenames like @file{help.LL.txt} with LL denoting the locale. GnuPG comes with a set of predefined help files in the data directory (e.g. @file{/usr/share/gnupg/help.de.txt}) and allows overriding of any help item by help files stored in the system configuration directory (e.g. @file{/etc/gnupg/help.de.txt}). For a reference of the help file's syntax, please see the installed @file{help.txt} file. @item com-certs.pem @cindex com-certs.pem This file is a collection of common certificates used to populated a newly created @file{pubring.kbx}. An administrator may replace this file with a custom one. The format is a concatenation of PEM encoded X.509 certificates. This global file is installed in the data directory (e.g. @file{/usr/share/gnupg/qualified.txt}). @end table @c man:.RE Note that on larger installations, it is useful to put predefined files into the directory @file{/etc/skel/.gnupg/} so that newly created users start up with a working configuration. For existing users the a small helper script is provided to create these files (@pxref{addgnupghome}). For internal purposes gpgsm creates and maintaines a few other files; they all live in in the current home directory (@pxref{option --homedir}). Only @command{gpgsm} may modify these files. @table @file @item pubring.kbx @cindex pubring.kbx This a database file storing the certificates as well as meta information. For debugging purposes the tool @command{kbxutil} may be used to show the internal structure of this file. @item random_seed @cindex random_seed This content of this file is used to maintain the internal state of the random number generator accross invocations. The same file is used by other programs of this software too. @item S.gpg-agent @cindex S.gpg-agent If this file exists and the environment variable @env{GPG_AGENT_INFO} is not set, @command{gpgsm} will first try to connect to this socket for accessing @command{gpg-agent} before starting a new @command{gpg-agent} instance. Under Windows this socket (which in reality be a plain file describing a regular TCP litening port) is the standard way of connecting the @command{gpg-agent}. @end table @c ******************************************* @c *************** **************** @c *************** EXAMPLES **************** @c *************** **************** @c ******************************************* @mansect examples @node GPGSM Examples @section Examples @example $ gpgsm -er goo@@bar.net ciphertext @end example @c man end @c ******************************************* @c *************** ************** @c *************** UNATTENDED ************** @c *************** ************** @c ******************************************* @node Unattended Usage @section Unattended Usage @command{gpgsm} is often used as a backend engine by other software. To help with this a machine interface has been defined to have an unambiguous way to do this. This is most likely used with the @code{--server} command but may also be used in the standard operation mode by using the @code{--status-fd} option. @menu * Automated signature checking:: Automated signature checking. @end menu @node Automated signature checking,,,Unattended Usage @section Automated signature checking It is very important to understand the semantics used with signature verification. Checking a signature is not as simple as it may sound and so the ooperation si a bit complicated. In mosted cases it is required to look at several status lines. Here is a table of all cases a signed message may have: @table @asis @item The signature is valid This does mean that the signature has been successfully verified, the certificates are all sane. However there are two subcases with important information: One of the certificates may have expired or a signature of a message itself as expired. It is a sound practise to consider such a signature still as valid but additional information should be displayed. Depending on the subcase @command{gpgsm} will issue these status codes: @table @asis @item signature valid and nothing did expire @code{GOODSIG}, @code{VALIDSIG}, @code{TRUST_FULLY} @item signature valid but at least one certificate has expired @code{EXPKEYSIG}, @code{VALIDSIG}, @code{TRUST_FULLY} @item signature valid but expired @code{EXPSIG}, @code{VALIDSIG}, @code{TRUST_FULLY} Note, that this case is currently not implemented. @end table @item The signature is invalid This means that the signature verification failed (this is an indication of af a transfer error, a programm error or tampering with the message). @command{gpgsm} issues one of these status codes sequences: @table @code @item @code{BADSIG} @item @code{GOODSIG}, @code{VALIDSIG} @code{TRUST_NEVER} @end table @item Error verifying a signature For some reason the signature could not be verified, i.e. it can't be decided whether the signature is valid or invalid. A common reason for this is a missing certificate. @end table @c ******************************************* @c *************** ***************** @c *************** ASSSUAN ***************** @c *************** ***************** @c ******************************************* @manpause @node GPGSM Protocol @section The Protocol the Server Mode Uses. Description of the protocol used to access @command{GPGSM}. @command{GPGSM} does implement the Assuan protocol and in addition provides a regular command line interface which exhibits a full client to this protocol (but uses internal linking). To start @command{gpgsm} as a server the command line the option @code{--server} must be used. Additional options are provided to select the communication method (i.e. the name of the socket). We assume that the connection has already been established; see the Assuan manual for details. @menu * GPGSM ENCRYPT:: Encrypting a message. * GPGSM DECRYPT:: Decrypting a message. * GPGSM SIGN:: Signing a message. * GPGSM VERIFY:: Verifying a message. * GPGSM GENKEY:: Generating a key. * GPGSM LISTKEYS:: List available keys. * GPGSM EXPORT:: Export certificates. * GPGSM IMPORT:: Import certificates. * GPGSM DELETE:: Delete certificates. * GPGSM GETINFO:: Information about the process @end menu @node GPGSM ENCRYPT @subsection Encrypting a Message Before encrytion can be done the recipient must be set using the command: @example RECIPIENT @var{userID} @end example Set the recipient for the encryption. @var{userID} should be the internal representation of the key; the server may accept any other way of specification. If this is a valid and trusted recipient the server does respond with OK, otherwise the return is an ERR with the reason why the recipient can't be used, the encryption will then not be done for this recipient. If the policy is not to encrypt at all if not all recipients are valid, the client has to take care of this. All @code{RECIPIENT} commands are cumulative until a @code{RESET} or an successful @code{ENCRYPT} command. @example INPUT FD[=@var{n}] [--armor|--base64|--binary] @end example Set the file descriptor for the message to be encrypted to @var{n}. Obviously the pipe must be open at that point, the server establishes its own end. If the server returns an error the client should consider this session failed. If @var{n} is not given, this commands uses the last file descriptor passed to the application. @xref{fun-assuan_sendfd, ,the assuan_sendfd function,assuan,the Libassuan manual}, on how to do descriptor passing. The @code{--armor} option may be used to advice the server that the input data is in @acronym{PEM} format, @code{--base64} advices that a raw base-64 encoding is used, @code{--binary} advices of raw binary input (@acronym{BER}). If none of these options is used, the server tries to figure out the used encoding, but this may not always be correct. @example OUTPUT FD[=@var{n}] [--armor|--base64] @end example Set the file descriptor to be used for the output (i.e. the encrypted message). Obviously the pipe must be open at that point, the server establishes its own end. If the server returns an error he client should consider this session failed. The option armor encodes the output in @acronym{PEM} format, the @code{--base64} option applies just a base 64 encoding. No option creates binary output (@acronym{BER}). The actual encryption is done using the command @example ENCRYPT @end example It takes the plaintext from the @code{INPUT} command, writes to the ciphertext to the file descriptor set with the @code{OUTPUT} command, take the recipients from all the recipients set so far. If this command fails the clients should try to delete all output currently done or otherwise mark it as invalid. @command{GPGSM} does ensure that there won't be any security problem with leftover data on the output in this case. This command should in general not fail, as all necessary checks have been done while setting the recipients. The input and output pipes are closed. @node GPGSM DECRYPT @subsection Decrypting a message Input and output FDs are set the same way as in encryption, but @code{INPUT} refers to the ciphertext and output to the plaintext. There is no need to set recipients. @command{GPGSM} automatically strips any @acronym{S/MIME} headers from the input, so it is valid to pass an entire MIME part to the INPUT pipe. The encryption is done by using the command @example DECRYPT @end example It performs the decrypt operation after doing some check on the internal state. (e.g. that all needed data has been set). Because it utilizes the GPG-Agent for the session key decryption, there is no need to ask the client for a protecting passphrase - GpgAgent takes care of this by requesting this from the user. @node GPGSM SIGN @subsection Signing a Message Signing is usually done with these commands: @example INPUT FD[=@var{n}] [--armor|--base64|--binary] @end example This tells @command{GPGSM} to read the data to sign from file descriptor @var{n}. @example OUTPUT FD[=@var{m}] [--armor|--base64] @end example Write the output to file descriptor @var{m}. If a detached signature is requested, only the signature is written. @example SIGN [--detached] @end example Sign the data set with the INPUT command and write it to the sink set by OUTPUT. With @code{--detached}, a detached signature is created (surprise). The key used for signining is the default one or the one specified in the configuration file. To get finer control over the keys, it is possible to use the command @example SIGNER @var{userID} @end example to the signer's key. @var{userID} should be the internal representation of the key; the server may accept any other way of specification. If this is a valid and trusted recipient the server does respond with OK, otherwise the return is an ERR with the reason why the key can't be used, the signature will then not be created using this key. If the policy is not to sign at all if not all keys are valid, the client has to take care of this. All @code{SIGNER} commands are cumulative until a @code{RESET} is done. Note that a @code{SIGN} does not reset this list of signers which is in contrats to the @code{RECIPIENT} command. @node GPGSM VERIFY @subsection Verifying a Message To verify a mesage the command: @example VERIFY @end example is used. It does a verify operation on the message send to the input FD. The result is written out using status lines. If an output FD was given, the signed text will be written to that. If the signature is a detached one, the server will inquire about the signed material and the client must provide it. @node GPGSM GENKEY @subsection Generating a Key This is used to generate a new keypair, store the secret part in the @acronym{PSE} and the public key in the key database. We will probably add optional commands to allow the client to select whether a hardware token is used to store the key. Configuration options to @command{GPGSM} can be used to restrict the use of this command. @example GENKEY @end example @command{GPGSM} checks whether this command is allowed and then does an INQUIRY to get the key parameters, the client should then send the key parameters in the native format: @example S: INQUIRE KEY_PARAM native C: D foo:fgfgfg C: D bar C: END @end example Please note that the server may send Status info lines while reading the data lines from the client. After this the key generation takes place and the server eventually does send an ERR or OK response. Status lines may be issued as a progress indicator. @node GPGSM LISTKEYS @subsection List available keys To list the keys in the internal database or using an external key provider, the command: @example LISTKEYS @var{pattern} @end example is used. To allow multiple patterns (which are ORed during the search) quoting is required: Spaces are to be translated into "+" or into "%20"; in turn this requires that the usual escape quoting rules are done. @example LISTSECRETKEYS @var{pattern} @end example Lists only the keys where a secret key is available. The list commands commands are affected by the option @example OPTION list-mode=@var{mode} @end example where mode may be: @table @code @item 0 Use default (which is usually the same as 1). @item 1 List only the internal keys. @item 2 List only the external keys. @item 3 List internal and external keys. @end table Note that options are valid for the entire session. @node GPGSM EXPORT @subsection Export certificates To export certificate from the internal key database the command: @example EXPORT [--data [--armor] [--base64]] [--] @var{pattern} @end example is used. To allow multiple patterns (which are ORed) quoting is required: Spaces are to be translated into "+" or into "%20"; in turn this requires that the usual escape quoting rules are done. If the @option{--data} option has not been given, the format of the output depends on what was set with the OUTPUT command. When using @acronym{PEM} encoding a few informational lines are prepended. If the @option{--data} has been given, a target set via OUTPUT is ignored and the data is returned inline using standard @code{D}-lines. This avoids the need for an extra file descriptor. In this case the options @option{--armor} and @option{--base64} may be used in the same way as with the OUTPUT command. @node GPGSM IMPORT @subsection Import certificates To import certificates into the internal key database, the command @example IMPORT @end example is used. The data is expected on the file descriptor set with the @code{INPUT} command. Certain checks are performend on the certificate. Note that the code will also handle PKCS\#12 files and import private keys; a helper program is used for that. @node GPGSM DELETE @subsection Delete certificates To delete a certificate the command @example DELKEYS @var{pattern} @end example is used. To allow multiple patterns (which are ORed) quoting is required: Spaces are to be translated into "+" or into "%20"; in turn this requires that the usual escape quoting rules are done. The certificates must be specified unambiguously otherwise an error is returned. @node GPGSM GETINFO @subsection Return information about the process This is a multipurpose function to return a variety of information. @example GETINFO @var{what} @end example The value of @var{what} specifies the kind of information returned: @table @code @item version Return the version of the program. @item pid Return the process id of the process. @end table @mansect see also @ifset isman @command{gpg2}(1), @command{gpg-agent}(1) @end ifset @include see-also-note.texi