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 @c Copyright (C) 2002 Klar"alvdalens Datakonsult AB
 @c Copyright (C) 2004, 2005, 2006, 2007 g10 Code GmbH
 @c This is part of the GnuPG manual.
 @c For copying conditions, see the file gnupg.texi.
 
 @include defs.inc
 
 @node Invoking DIRMNGR
 @chapter Invoking DIRMNGR
 @cindex DIRMNGR command options
 @cindex command options
 @cindex options, DIRMNGR command
 
 @manpage dirmngr.8
 @ifset manverb
 .B dirmngr
 \- CRL and OCSP daemon
 @end ifset
 
 @mansect synopsis
 @ifset manverb
 .B  dirmngr
 .RI [ options ]
 .I command
 .RI [ args ]
 @end ifset
 
 @mansect description
 Since version 2.1 of GnuPG, @command{dirmngr} takes care of accessing
 the OpenPGP keyservers.  As with previous versions it is also used as
 a server for managing and downloading certificate revocation lists
 (CRLs) for X.509 certificates, downloading X.509 certificates, and
 providing access to OCSP providers.  Dirmngr is invoked internally by
 @command{gpg}, @command{gpgsm}, or via the @command{gpg-connect-agent}
 tool.
 
 @manpause
 @noindent
 @xref{Option Index},for an index to @command{DIRMNGR}'s commands and
 options.
 @mancont
 
 @menu
 * Dirmngr Commands::      List of all commands.
 * Dirmngr Options::       List of all options.
 * Dirmngr Configuration:: Configuration files.
 * Dirmngr Signals::       Use of signals.
 * Dirmngr Examples::      Some usage examples.
 * Dirmngr Protocol::      The protocol dirmngr uses.
 @end menu
 
 
 @node Dirmngr Commands
 @section Commands
 @mansect commands
 
 Commands are not distinguished from options except for the fact that
 only one command is allowed.
 
 @table @gnupgtabopt
 @item --version
 @opindex version
 Print the program version and licensing information.  Note that you cannot
 abbreviate this command.
 
 @item --help, -h
 @opindex help
 Print a usage message summarizing the most useful command-line options.
 Note that you cannot abbreviate this command.
 
 @item --dump-options
 @opindex dump-options
 Print a list of all available options and commands.  Note that you cannot
 abbreviate this command.
 
 @item --server
 @opindex server
 Run in server mode and wait for commands on the @code{stdin}.  The
 default mode is to create a socket and listen for commands there.
 This is only used for testing.
 
 @item --daemon
 @opindex daemon
 Run in background daemon mode and listen for commands on a socket.
 This is the way @command{dirmngr} is started on demand by the other
 GnuPG components.  To force starting @command{dirmngr} it is in
 general best to use @code{gpgconf --launch dirmngr}.
 
 @item --supervised
 @opindex supervised
 Run in the foreground, sending logs to stderr, and listening on file
 descriptor 3, which must already be bound to a listening socket.  This
 is useful when running under systemd or other similar process
 supervision schemes.  This option is not supported on Windows.
 
 @item --list-crls
 @opindex list-crls
 List the contents of the CRL cache on @code{stdout}. This is probably
 only useful for debugging purposes.
 
 @item --load-crl @var{file}
 @opindex load-crl
 This command requires a filename as additional argument, and it will
 make Dirmngr try to import the CRL in @var{file} into it's cache.
 Note, that this is only possible if Dirmngr is able to retrieve the
 CA's certificate directly by its own means.  In general it is better
 to use @code{gpgsm}'s @code{--call-dirmngr loadcrl filename} command
 so that @code{gpgsm} can help dirmngr.
 
 @item --fetch-crl @var{url}
 @opindex fetch-crl
 This command requires an URL as additional argument, and it will make
 dirmngr try to retrieve and import the CRL from that @var{url} into
 it's cache.  This is mainly useful for debugging purposes.  The
 @command{dirmngr-client} provides the same feature for a running dirmngr.
 
 @item --shutdown
 @opindex shutdown
 This commands shuts down an running instance of Dirmngr.  This command
 has currently no effect.
 
 @item --flush
 @opindex flush
 This command removes all CRLs from Dirmngr's cache.  Client requests
 will thus trigger reading of fresh CRLs.
 
 @end table
 
 
 @mansect options
 @node Dirmngr Options
 @section Option Summary
 
 @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{dirmngr.conf} and expected in the home directory.
 
 @item --homedir @var{dir}
 @opindex options
 Set the name of the home directory to @var{dir}.  This option is only
-effective when used on the command line.  The default os
+effective when used on the command line.  The default is
 the directory named @file{.gnupg} directly below the home directory
 of the user unless the environment variable @code{GNUPGHOME} has been set
-in which case its value will be used.  All kind of data is stored below
+in which case its value will be used.  Many kinds of data are stored within
 this directory.
 
 
 @item -v
 @item --verbose
 @opindex v
 @opindex verbose
 Outputs additional information while running.
 You can increase the verbosity by giving several
 verbose commands to @sc{dirmngr}, such as @option{-vv}.
 
 
 @item --log-file @var{file}
 @opindex log-file
 Append all logging output to @var{file}.  This is very helpful in
 seeing what the agent actually does.  Use @file{socket://} to log to
 socket.
 
 @item --debug-level @var{level}
 @opindex debug-level
 Select the debug level for investigating problems.  @var{level} may be a
 numeric value or by a keyword:
 
 @table @code
 @item none
 No debugging at all.  A value of less than 1 may be used instead of
 the keyword.
 @item basic
 Some basic debug messages.  A value between 1 and 2 may be used
 instead of the keyword.
 @item advanced
 More verbose debug messages.  A value between 3 and 5 may be used
 instead of the keyword.
 @item expert
 Even more detailed messages.  A value between 6 and 8 may be used
 instead of the keyword.
 @item 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.
 @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 behavior may change at
 any time without notice.  FLAGS are bit encoded and may be given in
 usual C-Syntax.
 
 @item --debug-all
 @opindex debug-all
 Same as @code{--debug=0xffffffff}
 
 @item --gnutls-debug @var{level}
 @opindex gnutls-debug
 Enable debugging of GNUTLS at @var{level}.
 
 @item --debug-wait @var{n}
 @opindex debug-wait
 When running in server mode, wait @var{n} seconds before entering the
 actual processing loop and print the pid.  This gives time to attach a
 debugger.
 
 @item --disable-check-own-socket
 @opindex disable-check-own-socket
 On some platforms @command{dirmngr} is able to detect the removal of
 its socket file and shutdown itself.  This option disable this
 self-test for debugging purposes.
 
 @item -s
 @itemx --sh
 @itemx -c
 @itemx --csh
 @opindex s
 @opindex sh
 @opindex c
 @opindex csh
 Format the info output in daemon mode for use with the standard Bourne
 shell respective the C-shell. The default is to guess it based on the
 environment variable @code{SHELL} which is in almost all cases
 sufficient.
 
 @item --force
 @opindex force
 Enabling this option forces loading of expired CRLs; this is only
 useful for debugging.
 
 @item --use-tor
 @opindex use-tor
 This option switches Dirmngr and thus GnuPG into ``Tor mode'' to route
 all network access via Tor (an anonymity network).  WARNING: As of now
 this still leaks the DNS queries; e.g. to lookup the hosts in a
 keyserver pool.  Certain other features are disabled if this mode is
 active.
 
 @item --allow-version-check
 @opindex allow-version-check
 Allow Dirmngr to connect to @code{https://versions.gnupg.org} to get
 the list of current software versions.  If this option is enabled, or
 if @option{use-tor} is active, the list is retrieved when the local
 copy does not exist or is older than 5 to 7 days.  See the option
 @option{--query-swdb} of the command @command{gpgconf} for more
 details.
 
 @item --keyserver @var{name}
 @opindex keyserver
 Use @var{name} as your keyserver.  This is the server that @command{gpg}
 communicates with to receive keys, send keys, and search for
 keys.  The format of the @var{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 @option{--keyserver-options} of
 @command{gpg}, but apply only to this particular keyserver.
 
 Most keyservers synchronize with each other, so there is generally no
 need to send keys to more than one server. The keyserver
 @code{hkp://keys.gnupg.net} uses round robin DNS to give a different
 keyserver each time you use it.
 
 If exactly two keyservers are configured and only one is a Tor hidden
 service (.onion), Dirmngr selects the keyserver to use depending on
 whether Tor is locally running or not.  The check for a running Tor is
 done for each new connection.
 
 If no keyserver is explicitly configured, dirmngr will use the
 built-in default of hkps://hkps.pool.sks-keyservers.net.
 
 @item --nameserver @var{ipaddr}
 @opindex nameserver
 In ``Tor mode'' Dirmngr uses a public resolver via Tor to resolve DNS
 names.  If the default public resolver, which is @code{8.8.8.8}, shall
 not be used a different one can be given using this option.  Note that
 a numerical IP address must be given (IPv6 or IPv4) and that no error
 checking is done for @var{ipaddr}.  DNS queries in Tor mode do only
 work if GnuPG as been build with ADNS support.
 
 @item --disable-ldap
 @opindex disable-ldap
 Entirely disables the use of LDAP.
 
 @item --disable-http
 @opindex disable-http
 Entirely disables the use of HTTP.
 
 @item --ignore-http-dp
 @opindex ignore-http-dp
 When looking for the location of a CRL, the to be tested certificate
 usually contains so called @dfn{CRL Distribution Point} (DP) entries
 which are URLs describing the way to access the CRL.  The first found DP
 entry is used.  With this option all entries using the @acronym{HTTP}
 scheme are ignored when looking for a suitable DP.
 
 @item --ignore-ldap-dp
 @opindex ignore-ldap-dp
 This is similar to @option{--ignore-http-dp} but ignores entries using
 the @acronym{LDAP} scheme.  Both options may be combined resulting in
 ignoring DPs entirely.
 
 @item --ignore-ocsp-service-url
 @opindex ignore-ocsp-service-url
 Ignore all OCSP URLs contained in the certificate.  The effect is to
 force the use of the default responder.
 
 @item --honor-http-proxy
 @opindex honor-http-proxy
 If the environment variable @env{http_proxy} has been set, use its
 value to access HTTP servers.
 
 @item --http-proxy @var{host}[:@var{port}]
 @opindex http-proxy
 @efindex http_proxy
 Use @var{host} and @var{port} to access HTTP servers.  The use of this
 option overrides the environment variable @env{http_proxy} regardless
 whether @option{--honor-http-proxy} has been set.
 
 
 @item --ldap-proxy @var{host}[:@var{port}]
 @opindex ldap-proxy
 Use @var{host} and @var{port} to connect to LDAP servers.  If @var{port}
 is omitted, port 389 (standard LDAP port) is used.  This overrides any
 specified host and port part in a LDAP URL and will also be used if host
 and port have been omitted from the URL.
 
 @item --only-ldap-proxy
 @opindex only-ldap-proxy
 Never use anything else but the LDAP "proxy" as configured with
 @option{--ldap-proxy}.  Usually @command{dirmngr} tries to use other
 configured LDAP server if the connection using the "proxy" failed.
 
 
 @item --ldapserverlist-file @var{file}
 @opindex ldapserverlist-file
 Read the list of LDAP servers to consult for CRLs and certificates from
 file instead of the default per-user ldap server list file. The default
 value for @var{file} is @file{dirmngr_ldapservers.conf}.
 
 This server list file contains one LDAP server per line in the format
 
 @sc{hostname:port:username:password:base_dn}
 
 Lines starting with a  @samp{#} are comments.
 
 Note that as usual all strings entered are expected to be UTF-8 encoded.
 Obviously this will lead to problems if the password has originally been
 encoded as Latin-1.  There is no other solution here than to put such a
 password in the binary encoding into the file (i.e. non-ascii characters
 won't show up readable).@footnote{The @command{gpgconf} tool might be
 helpful for frontends as it enables editing this configuration file using
 percent-escaped strings.}
 
 
 @item --ldaptimeout @var{secs}
 @opindex ldaptimeout
 Specify the number of seconds to wait for an LDAP query before timing
 out. The default is currently 100 seconds.  0 will never timeout.
 
 
 @item --add-servers
 @opindex add-servers
 This option makes dirmngr add any servers it discovers when validating
 certificates against CRLs to the internal list of servers to consult for
 certificates and CRLs.
 
 This option is useful when trying to validate a certificate that has
 a CRL distribution point that points to a server that is not already
 listed in the ldapserverlist. Dirmngr will always go to this server and
 try to download the CRL, but chances are high that the certificate used
 to sign the CRL is located on the same server. So if dirmngr doesn't add
 that new server to list, it will often not be able to verify the
 signature of the CRL unless the @code{--add-servers} option is used.
 
 Note: The current version of dirmngr has this option disabled by default.
 
 
 @item --allow-ocsp
 @opindex allow-ocsp
 This option enables OCSP support if requested by the client.
 
 OCSP requests are rejected by default because they may violate the
 privacy of the user; for example it is possible to track the time when
 a user is reading a mail.
 
 
 @item --ocsp-responder @var{url}
 @opindex ocsp-responder
 Use @var{url} as the default OCSP Responder if the certificate does
 not contain information about an assigned responder.  Note, that
 @code{--ocsp-signer} must also be set to a valid certificate.
 
 @item --ocsp-signer @var{fpr}|@var{file}
 @opindex ocsp-signer
 Use the certificate with the fingerprint @var{fpr} to check the
 responses of the default OCSP Responder.  Alternatively a filename can be
 given in which case the response is expected to be signed by one of the
 certificates described in that file.  Any argument which contains a
 slash, dot or tilde is considered a filename.  Usual filename expansion
 takes place: A tilde at the start followed by a slash is replaced by the
 content of @env{HOME}, no slash at start describes a relative filename
 which will be searched at the home directory.  To make sure that the
 @var{file} is searched in the home directory, either prepend the name
 with "./" or use a name which contains a dot.
 
 If a response has been signed by a certificate described by these
 fingerprints no further check upon the validity of this certificate is
 done.
 
 The format of the @var{FILE} is a list of SHA-1 fingerprint, one per
 line with optional colons between the bytes.  Empty lines and lines
 prefix with a hash mark are ignored.
 
 
 @item --ocsp-max-clock-skew @var{n}
 @opindex ocsp-max-clock-skew
 The number of seconds a skew between the OCSP responder and them local
 clock is accepted.  Default is 600 (10 minutes).
 
 @item --ocsp-max-period @var{n}
 @opindex ocsp-max-period
 Seconds a response is at maximum considered valid after the time given
 in the thisUpdate field.  Default is 7776000 (90 days).
 
 @item --ocsp-current-period @var{n}
 @opindex ocsp-current-period
 The number of seconds an OCSP response is considered valid after the
 time given in the NEXT_UPDATE datum.  Default is 10800 (3 hours).
 
 
 @item --max-replies @var{n}
 @opindex max-replies
 Do not return more that @var{n} items in one query.  The default is
 10.
 
 @item --ignore-cert-extension @var{oid}
 @opindex ignore-cert-extension
 Add @var{oid} to the list of ignored certificate extensions.  The
 @var{oid} is expected to be in dotted decimal form, like
 @code{2.5.29.3}.  This option may be used more than once.  Critical
 flagged certificate extensions matching one of the OIDs in the list
 are treated as if they are actually handled and thus the certificate
 won't be rejected due to an unknown critical extension.  Use this
 option with care because extensions are usually flagged as critical
 for a reason.
 
 @item --hkp-cacert @var{file}
 Use the root certificates in @var{file} for verification of the TLS
 certificates used with @code{hkps} (keyserver access over TLS).  If
 the file is in PEM format a suffix of @code{.pem} is expected for
 @var{file}.  This option may be given multiple times to add more
 root certificates.  Tilde expansion is supported.
 
 If no @code{hkp-cacert} directive is present, dirmngr will make a
 reasonable choice: if the keyserver in question is the special pool
 @code{hkps.pool.sks-keyservers.net}, it will use the bundled root
 certificate for that pool.  Otherwise, it will use the system CAs.
 
 @end table
 
 
 @c
 @c Dirmngr Configuration
 @c
 @mansect files
 @node Dirmngr Configuration
 @section Configuration
 
 Dirmngr makes use of several directories when running in daemon mode:
 
 @table @file
 
 @item ~/.gnupg
 This is the standard home directory for all configuration files.
 
 @item /etc/gnupg/trusted-certs
 This directory should be filled with certificates of Root CAs you
 are trusting in checking the CRLs and signing OCSP Responses.
 
 Usually these are the same certificates you use with the applications
 making use of dirmngr.  It is expected that each of these certificate
 files contain exactly one @acronym{DER} encoded certificate in a file
 with the suffix @file{.crt} or @file{.der}.  @command{dirmngr} reads
 those certificates on startup and when given a SIGHUP.  Certificates
 which are not readable or do not make up a proper X.509 certificate
 are ignored; see the log file for details.
 
 Applications using dirmngr (e.g. gpgsm) can request these
 certificates to complete a trust chain in the same way as with the
 extra-certs directory (see below).
 
 Note that for OCSP responses the certificate specified using the option
 @option{--ocsp-signer} is always considered valid to sign OCSP requests.
 
 @item /etc/gnupg/extra-certs
 This directory may contain extra certificates which are preloaded
 into the internal cache on startup. Applications using dirmngr (e.g. gpgsm)
 can request cached certificates to complete a trust chain.
 This is convenient in cases you have a couple intermediate CA certificates
 or certificates usually used to sign OCSP responses.
 These certificates are first tried before going
 out to the net to look for them.  These certificates must also be
 @acronym{DER} encoded and suffixed with @file{.crt} or @file{.der}.
 
 @item ~/.gnupg/crls.d
 This directory is used to store cached CRLs.  The @file{crls.d}
 part will be created by dirmngr if it does not exists but you need to
 make sure that the upper directory exists.
 
 @end table
 @manpause
 
 To be able to see what's going on you should create the configure file
 @file{~/gnupg/dirmngr.conf} with at least one line:
 
 @example
 log-file ~/dirmngr.log
 @end example
 
 To be able to perform OCSP requests you probably want to add the line:
 
 @example
 allow-ocsp
 @end example
 
 To make sure that new options are read and that after the installation
 of a new GnuPG versions the installed dirmngr is running, you may want
 to kill an existing dirmngr first:
 
 @example
 gpgconf --kill dirmngr
 @end example
 
 You may check the log file to see whether all desired root
 certificates have been loaded correctly.
 
 
 @c
 @c Dirmngr Signals
 @c
 @mansect signals
 @node Dirmngr Signals
 @section Use of signals
 
 A running @command{dirmngr} may be controlled by signals, i.e. using
 the @command{kill} command to send a signal to the process.
 
 Here is a list of supported signals:
 
 @table @gnupgtabopt
 
 @item SIGHUP
 @cpindex SIGHUP
 This signal flushes all internally cached CRLs as well as any cached
 certificates.  Then the certificate cache is reinitialized as on
 startup.  Options are re-read from the configuration file.  Instead of
 sending this signal it is better to use
 @example
 gpgconf --reload dirmngr
 @end example
 
 @item SIGTERM
 @cpindex SIGTERM
 Shuts down the process but waits until all current requests are
 fulfilled.  If the process has received 3 of these signals and requests
 are still pending, a shutdown is forced.  You may also use
 @example
 gpgconf --kill dirmngr
 @end example
 instead of this signal
 
 @item SIGINT
 @cpindex SIGINT
 Shuts down the process immediately.
 
 
 @item SIGUSR1
 @cpindex SIGUSR1
 This prints some caching statistics to the log file.
 
 @end table
 
 
 
 @c
 @c  Examples
 @c
 @mansect examples
 @node Dirmngr Examples
 @section Examples
 
 Here is an example on how to show dirmngr's internal table of OpenPGP
 keyserver addresses.  The output is intended for debugging purposes
 and not part of a defined API.
 
 @example
   gpg-connect-agent --dirmngr 'keyserver --hosttable' /bye
 @end example
 
 To inhibit the use of a particular host you have noticed in one of the
 keyserver pools, you may use
 
 @example
  gpg-connect-agent --dirmngr 'keyserver --dead pgpkeys.bnd.de' /bye
 @end example
 
 The description of the @code{keyserver} command can be printed using
 
 @example
  gpg-connect-agent --dirmngr 'help keyserver' /bye
 @end example
 
 
 
 @c
 @c  Assuan Protocol
 @c
 @manpause
 @node Dirmngr Protocol
 @section Dirmngr's Assuan Protocol
 
 Assuan is the IPC protocol used to access dirmngr.  This is a
 description of the commands implemented by dirmngr.
 
 @menu
 * Dirmngr LOOKUP::      Look up a certificate via LDAP
 * Dirmngr ISVALID::     Validate a certificate using a CRL or OCSP.
 * Dirmngr CHECKCRL::    Validate a certificate using a CRL.
 * Dirmngr CHECKOCSP::   Validate a certificate using OCSP.
 * Dirmngr CACHECERT::   Put a certificate into the internal cache.
 * Dirmngr VALIDATE::    Validate a certificate for debugging.
 @end menu
 
 @node Dirmngr LOOKUP
 @subsection Return the certificate(s) found
 
 Lookup certificate.  To allow multiple patterns (which are ORed)
 quoting is required: Spaces are to be translated into "+" or into
 "%20"; obviously this requires that the usual escape quoting rules
 are applied.  The server responds with:
 
 @example
   S: D <DER encoded certificate>
   S: END
   S: D <second DER encoded certificate>
   S: END
   S: OK
 @end example
 
 In this example 2 certificates are returned.  The server may return
 any number of certificates; OK will also be returned when no
 certificates were found.  The dirmngr might return a status line
 
 @example
   S: S TRUNCATED <n>
 @end example
 
 
 To indicate that the output was truncated to N items due to a
 limitation of the server or by an arbitrary set limit.
 
 The option @option{--url} may be used if instead of a search pattern a
 complete URL to the certificate is known:
 
 @example
   C: LOOKUP --url CN%3DWerner%20Koch,o%3DIntevation%20GmbH,c%3DDE?userCertificate
 @end example
 
 If the option @option{--cache-only} is given, no external lookup is done
 so that only certificates from the cache are returned.
 
 With the option @option{--single}, the first and only the first match
 will be returned.  Unless option @option{--cache-only} is also used, no
 local lookup will be done in this case.
 
 
 
 @node Dirmngr ISVALID
 @subsection Validate a certificate using a CRL or OCSP
 
 @example
   ISVALID [--only-ocsp] [--force-default-responder] @var{certid}|@var{certfpr}
 @end example
 
 Check whether the certificate described by the @var{certid} has been
 revoked.  Due to caching, the Dirmngr is able to answer immediately in
 most cases.
 
 The @var{certid} is a hex encoded string consisting of two parts,
 delimited by a single dot.  The first part is the SHA-1 hash of the
 issuer name and the second part the serial number.
 
 Alternatively the certificate's SHA-1 fingerprint @var{certfpr} may be
 given in which case an OCSP request is done before consulting the CRL.
 If the option @option{--only-ocsp} is given, no fallback to a CRL check
 will be used.  If the option @option{--force-default-responder} is
 given, only the default OCSP responder will be used and any other
 methods of obtaining an OCSP responder URL won't be used.
 
 @noindent
 Common return values are:
 
 @table @code
 @item GPG_ERR_NO_ERROR (0)
 This is the positive answer: The certificate is not revoked and we have
 an up-to-date revocation list for that certificate.  If OCSP was used
 the responder confirmed that the certificate has not been revoked.
 
 @item GPG_ERR_CERT_REVOKED
 This is the negative answer: The certificate has been revoked.  Either
 it is in a CRL and that list is up to date or an OCSP responder informed
 us that it has been revoked.
 
 @item GPG_ERR_NO_CRL_KNOWN
 No CRL is known for this certificate or the CRL is not valid or out of
 date.
 
 @item GPG_ERR_NO_DATA
 The OCSP responder returned an ``unknown'' status.  This means that it
 is not aware of the certificate's status.
 
 @item GPG_ERR_NOT_SUPPORTED
 This is commonly seen if OCSP support has not been enabled in the
 configuration.
 @end table
 
 If DirMngr has not enough information about the given certificate (which
 is the case for not yet cached certificates), it will will inquire the
 missing data:
 
 @example
   S: INQUIRE SENDCERT <CertID>
   C: D <DER encoded certificate>
   C: END
 @end example
 
 A client should be aware that DirMngr may ask for more than one
 certificate.
 
 If Dirmngr has a certificate but the signature of the certificate
 could not been validated because the root certificate is not known to
 dirmngr as trusted, it may ask back to see whether the client trusts
 this the root certificate:
 
 @example
   S: INQUIRE ISTRUSTED <CertHexfpr>
   C: D 1
   C: END
 @end example
 
 Only this answer will let Dirmngr consider the certificate as valid.
 
 
 @node Dirmngr CHECKCRL
 @subsection Validate a certificate using a CRL
 
 Check whether the certificate with FINGERPRINT (SHA-1 hash of the
 entire X.509 certificate blob) is valid or not by consulting the CRL
 responsible for this certificate.  If the fingerprint has not been
 given or the certificate is not known, the function inquires the
 certificate using:
 
 @example
   S: INQUIRE TARGETCERT
   C: D <DER encoded certificate>
   C: END
 @end example
 
 Thus the caller is expected to return the certificate for the request
 (which should match FINGERPRINT) as a binary blob.  Processing then
 takes place without further interaction; in particular dirmngr tries
 to locate other required certificate by its own mechanism which
 includes a local certificate store as well as a list of trusted root
 certificates.
 
 @noindent
 The return code is 0 for success; i.e. the certificate has not been
 revoked or one of the usual error codes from libgpg-error.
 
 @node Dirmngr CHECKOCSP
 @subsection Validate a certificate using OCSP
 
 @example
   CHECKOCSP [--force-default-responder] [@var{fingerprint}]
 @end example
 
 Check whether the certificate with @var{fingerprint} (the SHA-1 hash of
 the entire X.509 certificate blob) is valid by consulting the appropriate
 OCSP responder.  If the fingerprint has not been given or the
 certificate is not known by Dirmngr, the function inquires the
 certificate using:
 
 @example
   S: INQUIRE TARGETCERT
   C: D <DER encoded certificate>
   C: END
 @end example
 
 Thus the caller is expected to return the certificate for the request
 (which should match @var{fingerprint}) as a binary blob.  Processing
 then takes place without further interaction; in particular dirmngr
 tries to locate other required certificates by its own mechanism which
 includes a local certificate store as well as a list of trusted root
 certificates.
 
 If the option @option{--force-default-responder} is given, only the
 default OCSP responder is used.  This option is the per-command variant
 of the global option @option{--ignore-ocsp-service-url}.
 
 
 @noindent
 The return code is 0 for success; i.e. the certificate has not been
 revoked or one of the usual error codes from libgpg-error.
 
 @node Dirmngr CACHECERT
 @subsection Put a certificate into the internal cache
 
 Put a certificate into the internal cache.  This command might be
 useful if a client knows in advance certificates required for a test and
 wants to make sure they get added to the internal cache.  It is also
 helpful for debugging.  To get the actual certificate, this command
 immediately inquires it using
 
 @example
   S: INQUIRE TARGETCERT
   C: D <DER encoded certificate>
   C: END
 @end example
 
 Thus the caller is expected to return the certificate for the request
 as a binary blob.
 
 @noindent
 The return code is 0 for success; i.e. the certificate has not been
 successfully cached or one of the usual error codes from libgpg-error.
 
 @node Dirmngr VALIDATE
 @subsection Validate a certificate for debugging
 
 Validate a certificate using the certificate validation function used
 internally by dirmngr.  This command is only useful for debugging.  To
 get the actual certificate, this command immediately inquires it using
 
 @example
   S: INQUIRE TARGETCERT
   C: D <DER encoded certificate>
   C: END
 @end example
 
 Thus the caller is expected to return the certificate for the request
 as a binary blob.
 
 
 @mansect see also
 @ifset isman
 @command{gpgsm}(1),
 @command{dirmngr-client}(1)
 @end ifset
 @include see-also-note.texi
 
 @c
 @c !!! UNDER CONSTRUCTION !!!
 @c
 @c
 @c @section Verifying a Certificate
 @c
 @c There are several ways to request services from Dirmngr.  Almost all of
 @c them are done using the Assuan protocol.  What we describe here is the
 @c Assuan command CHECKCRL as used for example by the dirmnr-client tool if
 @c invoked as
 @c
 @c @example
 @c   dirmngr-client foo.crt
 @c @end example
 @c
 @c This command will send an Assuan request to an already running Dirmngr
 @c instance.  foo.crt is expected to be a standard X.509 certificate and
 @c dirmngr will receive the Assuan command
 @c
 @c @example
 @c    CHECKCRL @var [{fingerprint}]
 @c @end example
 @c
 @c @var{fingerprint} is optional and expected to be the SHA-1 has of the
 @c DER encoding of the certificate under question.  It is to be HEX
 @c encoded.  The rationale for sending the fingerprint is that it allows
 @c dirmngr to reply immediately if it has already cached such a request.  If
 @c this is not the case and no certificate has been found in dirmngr's
 @c internal certificate storage, dirmngr will request the certificate using
 @c the Assuan inquiry
 @c
 @c @example
 @c       INQUIRE TARGETCERT
 @c @end example
 @c
 @c The caller (in our example dirmngr-client) is then expected to return
 @c the certificate for the request (which should match @var{fingerprint})
 @c as a binary blob.
 @c
 @c Dirmngr now passes control to @code{crl_cache_cert_isvalid}.  This
 @c function checks whether a CRL item exists for target certificate.  These
 @c CRL items are kept in a database of already loaded and verified CRLs.
 @c This mechanism is called the CRL cache.  Obviously timestamps are kept
 @c there with each item to cope with the expiration date of the CRL.  The
 @c possible return values are: @code{0} to indicate that a valid CRL is
 @c available for the certificate and the certificate itself is not listed
 @c in this CRL, @code{GPG_ERR_CERT_REVOKED} to indicate that the certificate is
 @c listed in the CRL or @code{GPG_ERR_NO_CRL_KNOWN} in cases where no CRL or no
 @c information is available.  The first two codes are immediately returned to
 @c the caller and the processing of this request has been done.
 @c
 @c Only the @code{GPG_ERR_NO_CRL_KNOWN} needs more attention: Dirmngr now
 @c calls @code{clr_cache_reload_crl} and if this succeeds calls
 @c @code{crl_cache_cert_isvald) once more.  All further errors are
 @c immediately returned to the caller.
 @c
 @c @code{crl_cache_reload_crl} is the actual heart of the CRL management.
 @c It locates the corresponding CRL for the target certificate, reads and
 @c verifies this CRL and stores it in the CRL cache.  It works like this:
 @c
 @c * Loop over all crlDPs in the target certificate.
 @c     * If the crlDP is invalid immediately terminate the loop.
 @c     * Loop over all names in the current crlDP.
 @c         * If the URL scheme is unknown or not enabled
 @c           (--ignore-http-dp, --ignore-ldap-dp) continues with
 @c           the next name.
 @c         * @code{crl_fetch} is called to actually retrieve the CRL.
 @c           In case of problems this name is ignore and we continue with
 @c           the next name.  Note that @code{crl_fetch} does only return
 @c           a descriptor for the CRL for further reading so does the CRL
 @c           does not yet end up in memory.
 @c         * @code{crl_cache_insert} is called with that descriptor to
 @c           actually read the CRL into the cache. See below for a
 @c           description of this function.  If there is any error (e.g. read
 @c           problem, CRL not correctly signed or verification of signature
 @c           not possible), this descriptor is rejected and we continue
 @c           with the next name.  If the CRL has been successfully loaded,
 @c           the loop is terminated.
 @c * If no crlDP has been found in the previous loop use a default CRL.
 @c   Note, that if any crlDP has been found but loading of the CRL failed,
 @c   this condition is not true.
 @c     * Try to load a CRL from all configured servers (ldapservers.conf)
 @c       in turn.  The first server returning a CRL is used.
 @c     * @code(crl_cache_insert) is then used to actually insert the CRL
 @c       into the cache.  If this failed we give up immediately without
 @c       checking the rest of the servers from the first step.
 @c * Ready.
 @c
 @c
 @c The @code{crl_cache_insert} function takes care of reading the bulk of
 @c the CRL, parsing it and checking the signature.  It works like this: A
 @c new database file is created using a temporary file name.  The CRL
 @c parsing machinery is started and all items of the CRL are put into
 @c this database file.  At the end the issuer certificate of the CRL
 @c needs to be retrieved.  Three cases are to be distinguished:
 @c
 @c  a) An authorityKeyIdentifier with an issuer and serialno exits: The
 @c     certificate is retrieved using @code{find_cert_bysn}.  If
 @c     the certificate is in the certificate cache, it is directly
 @c     returned. Then the requester (i.e. the client who requested the
 @c     CRL check) is asked via the Assuan inquiry ``SENDCERT'' whether
 @c     he can provide this certificate.  If this succeed the returned
 @c     certificate gets cached and returned.  Note, that dirmngr does not
 @c     verify in any way whether the expected certificate is returned.
 @c     It is in the interest of the client to return a useful certificate
 @c     as otherwise the service request will fail due to a bad signature.
 @c     The last way to get the certificate is by looking it up at
 @c     external resources.  This is done using the @code{ca_cert_fetch}
 @c     and @code{fetch_next_ksba_cert} and comparing the returned
 @c     certificate to match the requested issuer and seriano (This is
 @c     needed because the LDAP layer may return several certificates as
 @c     LDAP as no standard way to retrieve by serial number).
 @c
 @c  b) An authorityKeyIdentifier with a key ID exists: The certificate is
 @c     retrieved using @code{find_cert_bysubject}.  If the certificate is
 @c     in the certificate cache, it is directly returned.  Then the
 @c     requester is asked via the Assuan inquiry ``SENDCERT_SKI'' whether
 @c     he can provide this certificate.  If this succeed the returned
 @c     certificate gets cached and returned.  Note, that dirmngr does not
 @c     verify in any way whether the expected certificate is returned.
 @c     It is in the interest of the client to return a useful certificate
 @c     as otherwise the service request will fail due to a bad signature.
 @c     The last way to get the certificate is by looking it up at
 @c     external resources.  This is done using the @code{ca_cert_fetch}
 @c     and @code{fetch_next_ksba_cert} and comparing the returned
 @c     certificate to match the requested subject and key ID.
 @c
 @c  c) No authorityKeyIdentifier exits: The certificate is retrieved
 @c     using @code{find_cert_bysubject} without the key ID argument.  If
 @c     the certificate is in the certificate cache the first one with a
 @c     matching subject is is directly returned.  Then the requester is
 @c     asked via the Assuan inquiry ``SENDCERT'' and an exact
 @c     specification of the subject whether he can
 @c     provide this certificate.  If this succeed the returned
 @c     certificate gets cached and returned.  Note, that dirmngr does not
 @c     verify in any way whether the expected certificate is returned.
 @c     It is in the interest of the client to return a useful certificate
 @c     as otherwise the service request will fail due to a bad signature.
 @c     The last way to get the certificate is by looking it up at
 @c     external resources.  This is done using the @code{ca_cert_fetch}
 @c     and @code{fetch_next_ksba_cert} and comparing the returned
 @c     certificate to match the requested subject; the first certificate
 @c     with a matching subject is then returned.
 @c
 @c If no certificate was found, the function returns with the error
 @c GPG_ERR_MISSING_CERT.  Now the signature is verified.  If this fails,
 @c the erro is returned.  On success the @code{validate_cert_chain} is
 @c used to verify that the certificate is actually valid.
 @c
 @c Here we may encounter a recursive situation:
 @c @code{validate_cert_chain} needs to look at other certificates and
 @c also at CRLs to check whether these other certificates and well, the
 @c CRL issuer certificate itself are not revoked.  FIXME: We need to make
 @c sure that @code{validate_cert_chain} does not try to lookup the CRL we
 @c are currently processing. This would be a catch-22 and may indicate a
 @c broken PKI.  However, due to overlapping expiring times and imprecise
 @c clocks this may actually happen.
 @c
 @c For historical reasons the Assuan command ISVALID is a bit different
 @c to CHECKCRL but this is mainly due to different calling conventions.
 @c In the end the same fucntionality is used, albeit hidden by a couple
 @c of indirection and argument and result code mangling.  It furthere
 @c ingetrages OCSP checking depending on options are the way it is
 @c called.  GPGSM still uses this command but might eventuall switch over
 @c to CHECKCRL and CHECKOCSP so that ISVALID can be retired.
 @c
 @c
 @c @section Validating a certificate
 @c
 @c We describe here how the internal function @code{validate_cert_chain}
 @c works. Note that mainly testing purposes this functionality may be
 @c called directly using @cmd{dirmngr-client --validate @file{foo.crt}}.
 @c
 @c The function takes the target certificate and a mode argument as
 @c parameters and returns an error code and optionally the closes
 @c expiration time of all certificates in the chain.
 @c
 @c We first check that the certificate may be used for the requested
 @c purpose (i.e. OCSP or CRL signing).  If this is not the case
 @c GPG_ERR_WRONG_KEY_USAGE is returned.
 @c
 @c The next step is to find the trust anchor (root certificate) and to
 @c assemble the chain in memory: Starting with the target certificate,
 @c the expiration time is checked against the current date, unknown
 @c critical extensions are detected and certificate policies are matched
 @c (We only allow 2.289.9.9 but I have no clue about that OID and from
 @c where I got it - it does not even seem to be assigned - debug cruft?).
 @c
 @c Now if this certificate is a self-signed one, we have reached the
 @c trust anchor.  In this case we check that the signature is good, the
 @c certificate is allowed to act as a CA, that it is a trusted one (by
 @c checking whether it is has been put into the trusted-certs
 @c configuration directory) and finally prepend into to our list
 @c representing the certificate chain.  This steps ends then.
 @c
 @c If it is not a self-signed certificate, we check that the chain won't
 @c get too long (current limit is 100), if this is the case we terminate
 @c with the error GPG_ERR_BAD_CERT_CHAIN.
 @c
 @c Now the issuer's certificate is looked up: If an
 @c authorityKeyIdentifier is available, this one is used to locate the
 @c certificate either using issuer and serialnumber or subject DN
 @c (i.e. the issuer's DN) and the keyID.  The functions
 @c @code{find_cert_bysn) and @code{find_cert_bysubject} are used
 @c respectively. The have already been described above under the
 @c description of @code{crl_cache_insert}.  If no certificate was found
 @c or with no authorityKeyIdentifier, only the cache is consulted using
 @c @code{get_cert_bysubject}.  The latter is is done under the assumption
 @c that a matching certificate has explicitly been put into the
 @c certificate cache.  If the issuer's certificate could not be found,
 @c the validation terminates with the error code @code{GPG_ERR_MISSING_CERT}.
 @c
 @c If the issuer's certificate has been found, the signature of the
 @c actual certificate is checked and in case this fails the error
 @c #code{GPG_ERR_BAD_CERT_CHAIN} is returned.  If the signature checks out, the
 @c maximum chain length of the issuing certificate is checked as well as
 @c the capability of the certificate (i.e. whether he may be used for
 @c certificate signing).  Then the certificate is prepended to our list
 @c representing the certificate chain.  Finally the loop is continued now
 @c with the issuer's certificate as the current certificate.
 @c
 @c After the end of the loop and if no error as been encountered
 @c (i.e. the certificate chain has been assempled correctly), a check is
 @c done whether any certificate expired or a critical policy has not been
 @c met.  In any of these cases the validation terminates with an
 @c appropriate error.
 @c
 @c Finally the function @code{check_revocations} is called to verify no
 @c certificate in the assempled chain has been revoked: This is an
 @c recursive process because a CRL has to be checked for each certificate
 @c in the chain except for the root certificate, of which we already know
 @c that it is trusted and we avoid checking a CRL here due to common
 @c setup problems and the assumption that a revoked root certifcate has
 @c been removed from the list of trusted certificates.
 @c
 @c
 @c
 @c
 @c @section Looking up certificates through LDAP.
 @c
 @c This describes the LDAP layer to retrieve certificates.
 @c the functions @code{ca_cert_fetch} and @code{fetch_next_ksba_cert} are
 @c used for this.  The first one starts a search and the second one is
 @c used to retrieve certificate after certificate.
 @c