                       The GNU Privacy Guard
                      =======================
                            Version 2.4

          Copyright 1997-2019 Werner Koch
          Copyright 1998-2021 Free Software Foundation, Inc.
          Copyright 2003-2025 g10 Code GmbH


* INTRODUCTION

  GnuPG is a complete and free implementation of the OpenPGP standard
  as defined by RFC4880 (also known as PGP).  GnuPG enables encryption
  and signing of data and communication, and features a versatile key
  management system as well as access modules for public key
  directories.

  GnuPG, also known as GPG, is a command line tool with features for
  easy integration with other applications.  A wealth of frontend
  applications and libraries are available that make use of GnuPG.
  Starting with version 2 GnuPG provides support for S/MIME and Secure
  Shell in addition to OpenPGP.

  GnuPG is Free Software (meaning that it respects your freedom). It
  can be freely used, modified and distributed under the terms of the
  GNU General Public License.

* BUILD INSTRUCTIONS

  GnuPG 2.4 depends on the following GnuPG related packages:

    npth         (https://gnupg.org/ftp/gcrypt/npth/)
    libgpg-error (https://gnupg.org/ftp/gcrypt/libgpg-error/)
    libgcrypt    (https://gnupg.org/ftp/gcrypt/libgcrypt/)
    libksba      (https://gnupg.org/ftp/gcrypt/libksba/)
    libassuan    (https://gnupg.org/ftp/gcrypt/libassuan/)

  You should get the latest versions of course, the GnuPG configure
  script complains if a version is not sufficient.

  Several other standard libraries are also required.  The configure
  script prints diagnostic messages if one of these libraries is not
  available and a feature will not be available.

  You also need the Pinentry package for most functions of GnuPG;
  however it is not a build requirement.  Pinentry is available at
  https://gnupg.org/ftp/gcrypt/pinentry/ .

  After building and installing the above packages in the order as
  given above, you may continue with GnuPG installation (you may also
  just try to build GnuPG to see whether your already installed
  versions are sufficient).

  As with all packages, you just have to do

    mkdir build
    cd build
    ../configure
    make
    make check
    make install

  The "make check" is optional but highly recommended.  To run even
  more tests you may add "--enable-all-tests" to the configure run.
  Before running the "make install" you might need to become root.

  If everything succeeds, you have a working GnuPG with support for
  OpenPGP, S/MIME, ssh-agent, and smartcards.

  In case of problem please ask on the gnupg-users@gnupg.org mailing
  list for advise.

  Instruction on how to build for Windows can be found in the file
  doc/HACKING in the section "How to build an installer for Windows".
  This requires some experience as developer.

  You may run

    gpgconf -L

  to view the directories used by GnuPG.

** Quick build method on Unix

  To quickly build all required software without installing it, the
  Speedo target may be used:

    make -f build-aux/speedo.mk native

  This target downloads all required libraries and does a native build
  of GnuPG to PLAY/inst/.  GNU make and the patchelf tool are
  required.  After the build the entire software including all
  libraries can be installed into an arbitrary location using for
  example:

    make -f build-aux/speedo.mk install SYSROOT=/usr/local/gnupg24
    ldconfig -n /usr/local/gnupg24/lib

  and adding /usr/local/gnupg24/bin to PATH.


** Specific build problems on some machines:

*** Apple OSX 10.x using XCode

  On some versions the correct location of a header file can't be
  detected by configure.  To fix that you should run configure like
  this

    ./configure  gl_cv_absolute_stdint_h=/usr/include/stdint.h

  Add other options as needed.


*** Systems without a full C99 compiler

  If you run into problems with your compiler complaining about dns.c
  you may use

    ./configure --disable-libdns

  Add other options as needed.



* RECOMMENDATIONS

** Key database daemon

  Since version 2.3.0 it is possible to store the keys in an SQLite
  database instead of the keyring.kbx file.  This is in particular
  useful for large keyrings or if many instances of gpg and gpgsm may
  run concurrently.  This is implemented using another daemon process,
  the "keyboxd".  To enable the use of the keyboxd put the option
  "use-keyboxd" into the configuration file ~/.gnupg/common.conf or the
  global /etc/gnupg/common.conf.  See also doc/examples/common.conf.
  Only public keys and X.509 certificates are managed by the keyboxd;
  private keys are still stored as separate files.

  Since version 2.4.1 the keyboxd will be used by default for a fresh
  install; i.e. if a ~/.gnupg directory did not yet exist.

  Note that there is no automatic migration; if the use-keyboxd option
  is enabled keys are not taken from pubring.kbx.  To migrate existing
  keys to the keyboxd do this:

  1. Disable the keyboxd (remove use-keyboxd from common.conf)
  2. Export all public keys
       gpg --export --export-options backup  > allkeys.gpg
       gpgsm --export --armor                > allcerts.gpg
  3. Enable the keyboxd (add use-keyboxd to common.conf)
  4. Import all public keys
       gpg --import --import-options restore < allkeys.gpg
       gpgsm --import                        < allcerts.crt

  In case the keyboxd is not able to startup due to a stale lockfile
  created by another host, the command

     gpgconf --unlock pubring.db

  can be used to remove the lock file.

** Socket directory

  GnuPG uses Unix domain sockets to connect its components (on Windows
  an emulation of these sockets is used).  Depending on the type of
  the file system, it is sometimes not possible to use the GnuPG home
  directory (i.e. ~/.gnupg) as the location for the sockets.  To solve
  this problem GnuPG prefers the use of a per-user directory below the
  the /run (or /var/run) hierarchy for the sockets.  It is thus
  suggested to create per-user directories on system or session
  startup.  For example, the following snippet can be used in
  /etc/rc.local to create these directories:

      [ ! -d /run/user ] && mkdir /run/user
      awk -F: </etc/passwd '$3 >= 1000 && $3 < 65000 {print $3}' \
        | ( while read uid rest; do
              if [ ! -d "/run/user/$uid" ]; then
                mkdir /run/user/$uid
                chown $uid /run/user/$uid
                chmod 700 /run/user/$uid
              fi
            done )

** Conflicts with systemd socket activation

  Some Linux distribution use the meanwhile deprecated --supervised
  option with gpg-agent, dirmngr, and keyboxd.  The idea is that the
  systemd process launches the daemons as soon as gpg or gpgsm try to
  access them.  However, this creates a race condition with GnuPG's
  own on-demand launching of these daemon.  It also conflicts with the
  remote use gpg-agent because the no-autostart feature on the remote
  site will not work as expected.

  Thus the recommendation is not to use the --supervised option.  All
  GnuPG components handle the startup of their daemons on their own.

  The only problem is that for using GnuPG's ssh-agent protocol
  support, the gpg-agent must have been started before ssh.  This can
  either be done with an ssh wrapper running

    gpg-connect-agent updatestartuptty /bye

  for each new tty or by using that command directly after login when
  the anyway required SSH_AUTH_SOCK envvar is set (see the example in
  the gpg-agent man page).


* DOCUMENTATION

  The complete documentation is in the texinfo manual named
  `gnupg.info'.  Run "info gnupg" to read it.  If you want a
  printable copy of the manual, change to the "doc" directory and
  enter "make pdf" For a HTML version enter "make html" and point your
  browser to gnupg.html/index.html.  Standard man pages for all
  components are provided as well.  An online version of the manual is
  available at [[https://gnupg.org/documentation/manuals/gnupg/]] .  A
  version of the manual pertaining to the current development snapshot
  is at [[https://gnupg.org/documentation/manuals/gnupg-devel/]] .


* Using the legacy version GnuPG 1.4

  The 1.4 version of GnuPG is only intended to allow decryption of old
  data material using legacy keys which are not anymore supported by
  GnuPG 2.x.  To install both versions alongside, it is suggested to
  rename the 1.4 version of "gpg" to "gpg1" as well as the
  corresponding man page.  Newer releases of the 1.4 branch will
  likely do this by default.


* HOW TO GET MORE INFORMATION

  A description of new features and changes since version 2.1 can be
  found in the file "doc/whats-new-in-2.1.txt" and online at
  "https://gnupg.org/faq/whats-new-in-2.1.html" .

  The primary WWW page is "https://gnupg.org"
  The primary FTP site is "https://gnupg.org/ftp/gcrypt/"

  See [[https://gnupg.org/download/mirrors.html]] for a list of
  mirrors and use them if possible.  You may also find GnuPG mirrored
  on some of the regular GNU mirrors.

  We have some mailing lists dedicated to GnuPG:

     gnupg-announce@gnupg.org   For important announcements like new
                                versions and such stuff.  This is a
                                moderated list and has very low traffic.
                                Do not post to this list.

     gnupg-users@gnupg.org      For general user discussion and
                                help.

     gnupg-devel@gnupg.org      GnuPG developers main forum.

  You subscribe to one of the list by sending mail with a subject of
  "subscribe" to x-request@gnupg.org, where x is the name of the
  mailing list (gnupg-announce, gnupg-users, etc.). See
  https://gnupg.org/documentation/mailing-lists.html for archives
  of the mailing lists.

  Please direct bug reports to [[https://bugs.gnupg.org]] or post them
  direct to the mailing list <gnupg-devel@gnupg.org>.

  Please direct questions about GnuPG to the users mailing list or one
  of the PGP newsgroups; please do not direct questions to one of the
  authors directly as we are busy working on improvements and bug
  fixes.  The mailing lists are watched by the authors and we try to
  answer questions as time allows us.

  Commercial grade support for GnuPG is available; for a listing of
  offers see https://gnupg.org/service.html .  Maintaining and
  improving GnuPG requires a lot of time.  Since 2001, g10 Code GmbH,
  a German company owned and headed by GnuPG's principal author Werner
  Koch, is bearing the majority of these costs.

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