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- Committer: Bazaar Package Importer
- Author(s): Marc Deslauriers
- Date: 2011-05-25 14:27:35 UTC
- mfrom: (1.1.15 upstream) (7.1.7 sid)
- Revision ID: james.westby@ubuntu.com-20110525142735-jccyw0fopnyv728q
Tags: 2.0.17-2ubuntu1
* Merge from debian unstable. Remaining changes:
- Add udev rules to give gpg access to some smartcard readers;
Debian #543217.
. debian/gnupg2.dev: udev rules to set ACLs on SCM smartcard readers.
. debian/rules: Call dh_installudev.
- debian/control: Rename Vcs-* to XS-Debian-Vcs-*.
- Add udev rules to give gpg access to some smartcard readers;
Debian #543217.
. debian/gnupg2.dev: udev rules to set ACLs on SCM smartcard readers.
. debian/rules: Call dh_installudev.
- debian/control: Rename Vcs-* to XS-Debian-Vcs-*.
- files added:
- .pc/debian-changes-2.0.17-2
- .pc/debian-changes-2.0.17-2ubuntu1
- files removed:
- .pc/01-gnupg2-rename.diff/doc
- .pc/02-encode-s2k.diff
- .pc/02-encode-s2k.diff/agent
- .pc/03-gpgsm-realloc.diff
- .pc/03-gpgsm-realloc.diff/kbx
- .pc/debian-changes-2.0.14-2
- files modified:
- .pc/01-gnupg2-rename.diff/configure.ac
added
removed
doc/faq.raw
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[$htmltitle=GnuPG FAQ]
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[$htmlcharset=<meta http-equiv="content-type" content="text/html; charset=utf-8">]
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[$sfaqheader=The GnuPG FAQ says:]
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[$sfaqfooter=
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The most recent version of the FAQ is available from
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<http://www.gnupg.org/>
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]
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[$usenetheader=
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]
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[$maintainer=David D. Scribner, <faq 'at' gnupg.org>]
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[$hGPGHTTP=http://www.gnupg.org]
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[$hGPGFTP=ftp://ftp.gnupg.org]
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[$hVERSION=1.2.2]
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[H body bgcolor=#ffffff text=#000000 link=#1f00ff alink=#ff0000 vlink=#9900dd]
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[H h1]GnuPG Frequently Asked Questions[H /h1]
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[H p]
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Version: 1.6.3[H br]
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Last-Modified: Jul 30, 2003[H br]
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Maintained-by: [$maintainer]
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[H /p]
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This is the GnuPG FAQ. The latest HTML version is available
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[H a href=[$hGPGHTTP]/documentation/faqs.html]here[H/a].
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The index is generated automatically, so there may be errors. Not all
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questions may be in the section they belong to. Suggestions about how
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to improve the structure of this FAQ are welcome.
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Please send additions and corrections to the maintainer. It would be
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most convenient if you could provide the answer to be included here
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as well. Your help is very much appreciated!
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Please, don't send message like "This should be a FAQ - what's the
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answer?". If it hasn't been asked before, it isn't a FAQ. In that case
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you could search in the mailing list archive.
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[H hr]
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<C>
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[H hr]
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<S> GENERAL
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<Q> What is GnuPG?
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[H a href=[$hGPGHTTP]]GnuPG[H /a] stands for GNU Privacy Guard and
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is GNU's tool for secure communication and data storage. It can be
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used to encrypt data and to create digital signatures. It includes
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an advanced key management facility and is compliant with the
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proposed OpenPGP Internet standard as described in [H a href=http://www.rfc-editor.org/]RFC 2440[H/a].
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As such, it is aimed to be compatible with PGP from PGP Corp. and
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other OpenPGP tools
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<Q> Is GnuPG compatible with PGP?
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In general, yes. GnuPG and newer PGP releases should be implementing
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the OpenPGP standard. But there are some interoperability problems.
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See question <Rcompat> for details.
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<Q> Is GnuPG free to use for personal or commercial use?
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Yes. GnuPG is part of the GNU family of tools and applications built
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and provided in accordance with the Free Software Foundation (FSF)
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General Public License (GPL). Therefore the software is free to copy,
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use, modify and distribute in accordance with that license. Please
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read the file titled COPYING that accompanies the application for
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more information.
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<Q> What conventions are used in this FAQ?
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Although GnuPG is being developed for several operating systems
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(often in parallel), the conventions used in this FAQ reflect a
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UNIX shell environment. For Win32 users, references to a shell
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prompt (`$') should be interpreted as a command prompt (`>'),
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directory names separated by a forward slash (`/') may need to be
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converted to a back slash (`\'), and a tilde (`~') represents a
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user's "home" directory (reference question <Rhomedir> for an example).
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Some command-lines presented in this FAQ are too long to properly
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display in some browsers for the web page version of this file, and
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have been split into two or more lines. For these commands please
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remember to enter the entire command-string on one line or the
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command will error, or at minimum not give the desired results.
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Please keep in mind that this FAQ contains information that may not
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apply to your particular version, as new features and bug fixes are
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added on a continuing basis (reference the NEWS file included with
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the source or package for noteworthy changes between versions). One
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item to note is that starting with GnuPG version 1.1.92 the file
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containing user options and settings has been renamed from "options"
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to "gpg.conf". Information in the FAQ that relates to the options
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file may be interchangable with the newer gpg.conf file in many
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instances. See question <Roptions> for details.
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<S> SOURCES of INFORMATION
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<Q> Where can I find more information on GnuPG?
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On-line resources:
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[H ul]
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[H li]The documentation page is located at [H a href=[$hGPGHTTP]/documentation/]<[$hGPGHTTP]/documentation/>[H/a].
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Also, have a look at the HOWTOs and the GNU Privacy Handbook (GPH,
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available in English, Spanish and Russian). The latter provides a
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detailed user's guide to GnuPG. You'll also find a document about how
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to convert from PGP 2.x to GnuPG.
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[H li]At [H a href=[$hGPGHTTP]/documentation/mailing-lists.html]<[$hGPGHTTP]/documentation/mailing-lists.html>[H/a] you'll find
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an online archive of the GnuPG mailing lists. Most interesting should
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be gnupg-users for all user-related issues and gnupg-devel if you want
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to get in touch with the developers.
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In addition, searchable archives can be found on MARC, e.g.: [H br]
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gnupg-users: [H a href=http://marc.theaimsgroup.com/?l=gnupg-users&r=1&w=2]<http://marc.theaimsgroup.com/?l=gnupg-users&r=1&w=2>[H/a][H br]
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gnupg-devel: [H a href=http://marc.theaimsgroup.com/?l=gnupg-devel&r=1&w=2]<http://marc.theaimsgroup.com/?l=gnupg-devel&r=1&w=2>[H/a][H br]
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[H b]PLEASE:[H /b]
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Before posting to a list, read this FAQ and the available documentation.
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In addition, search the list archive - maybe your question has already
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been discussed. This way you help people focus on topics that have not
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yet been resolved.
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[H li]The GnuPG source distribution contains a subdirectory:
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[H samp]
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./doc
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[H /samp]
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where some additional documentation is located (mainly interesting
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for hackers, not the casual user).
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[H /ul]
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<Q> Where do I get GnuPG?
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You can download the GNU Privacy Guard from its primary FTP server
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[H a href=[$hGPGFTP]/gcrypt/]<[$hGPGFTP]/gcrypt/>[H /a] or from one of the mirrors:
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[H a href=[$hGPGHTTP]/download/mirrors.html]
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<[$hGPGHTTP]/download/mirrors.html>
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[H /a]
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The current stable version is [$hVERSION]. Please upgrade to this version as
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it includes additional features, functions and security fixes that may
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not have existed in prior versions.
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<S> INSTALLATION
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<Q> Which OSes does GnuPG run on?
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It should run on most Unices as well as Windows versions (including
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Windows NT/2000) and Macintosh OS/X. A list of OSes reported to be OK
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is presented at:
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[H a href=[$hGPGHTTP]/download/supported_systems.html]
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<[$hGPGHTTP]/download/supported_systems.html>
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[H /a]
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<Q> Which random data gatherer should I use?
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"Good" random numbers are crucial for the security of your encryption.
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Different operating systems provide a variety of more or less quality
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random data. Linux and *BSD provide kernel generated random data
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through /dev/random - this should be the preferred choice on these
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systems. Also Solaris users with the SUNWski package installed have
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a /dev/random. In these cases, use the configure option:
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[H samp]
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--enable-static-rnd=linux
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[H /samp]
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In addition, there's also the kernel random device by Andi Maier
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[H a href= http://www.cosy.sbg.ac.at/~andi/SUNrand/]<http://www.cosy.sbg.ac.at/~andi/SUNrand/>[H /a], but it's still beta. Use at your
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own risk!
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On other systems, the Entropy Gathering Daemon (EGD) is a good choice.
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It is a perl-daemon that monitors system activity and hashes it into
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random data. See the download page [H a href=[$hGPGHTTP]/download/]<[$hGPGHTTP]/download/>[H /a]
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to obtain EGD. Use:
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[H samp]
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--enable-static-rnd=egd
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[H /samp]
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here.
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If the above options do not work, you can use the random number
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generator "unix". This is [H B]very[H /B] slow and should be avoided. The
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random quality isn't very good so don't use it on sensitive data.
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<Didea>
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<Q> How do I include support for RSA and IDEA?
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RSA is included as of GnuPG version 1.0.3.
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The official GnuPG distribution does not contain IDEA due to a patent
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restriction. The patent does not expire before 2007 so don't expect
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official support before then.
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However, there is an unofficial module to include it even in earlier
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versions of GnuPG. It's available from
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[H a href=ftp://ftp.gnupg.dk/pub/contrib-dk/]<ftp://ftp.gnupg.dk/pub/contrib-dk/>[H /a]. Look for:
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[H pre]
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idea.c.gz (c module)
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idea.c.gz.sig (signature file)
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[H /pre]
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[H pre]
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ideadll.zip (c module and win32 dll)
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ideadll.zip.sig (signature file)
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[H /pre]
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Compilation directives are in the headers of these files. You will
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then need to add the following line to your ~/.gnupg/gpg.conf or
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~/.gnupg/options file:
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[H samp]
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load-extension idea
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[H /samp]
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<S> USAGE
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<Q> What is the recommended key size?
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1024 bit for DSA signatures; even for plain Elgamal signatures.
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This is sufficient as the size of the hash is probably the weakest
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link if the key size is larger than 1024 bits. Encryption keys may
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have greater sizes, but you should then check the fingerprint of
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this key:
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[H samp]
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$ gpg --fingerprint <user ID>
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[H /samp]
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As for the key algorithms, you should stick with the default (i.e.,
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DSA signature and Elgamal encryption). An Elgamal signing key has
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the following disadvantages: the signature is larger, it is hard
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to create such a key useful for signatures which can withstand some
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real world attacks, you don't get any extra security compared to
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DSA, and there might be compatibility problems with certain PGP
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versions. It has only been introduced because at the time it was
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not clear whether there was a patent on DSA.
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<Q> Why does it sometimes take so long to create keys?
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The problem here is that we need a lot of random bytes and for that
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we (on Linux the /dev/random device) must collect some random data.
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It is really not easy to fill the Linux internal entropy buffer; I
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talked to Ted Ts'o and he commented that the best way to fill the
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buffer is to play with your keyboard. Good security has its price.
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What I do is to hit several times on the shift, control, alternate,
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and caps lock keys, because these keys do not produce output to the
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screen. This way you get your keys really fast (it's the same thing
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PGP2 does).
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Another problem might be another program which eats up your random
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bytes (a program (look at your daemons) that reads from /dev/random).
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<Q> And it really takes long when I work on a remote system. Why?
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Don't do this at all! You should never create keys or even use GnuPG
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on a remote system because you normally have no physical control
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over your secret key ring (which is in most cases vulnerable to
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advanced dictionary attacks) - I strongly encourage everyone to only
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create keys on a local computer (a disconnected laptop is probably
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the best choice) and if you need it on your connected box (I know,
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we all do this) be sure to have a strong password for both your
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account and for your secret key, and that you can trust your system
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administrator.
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When I check GnuPG on a remote system via ssh (I have no Alpha here)
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;-) I have the same problem. It takes a *very* long time to create
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the keys, so I use a special option, --quick-random, to generate
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insecure keys which are only good for some tests.
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<Q> What is the difference between options and commands?
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If you do a 'gpg --help', you will get two separate lists. The first
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is a list of commands. The second is a list of options. Whenever you
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run GPG, you [H b]must[H /b] pick exactly one command (with one exception,
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see below). You [H b]may[H /b] pick one or more options. The command should,
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just by convention, come at the end of the argument list, after all
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the options. If the command takes a file (all the basic ones do),
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the filename comes at the very end. So the basic way to run gpg is:
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[H samp]
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$ gpg [--option something] [--option2] [--option3 something] --command file
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[H /samp]
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Some options take arguments. For example, the --output option (which
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can be abbreviated as -o) is an option that takes a filename. The
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option's argument must follow immediately after the option itself,
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otherwise gpg doesn't know which option the argument is supposed to
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paired with. As an option, --output and its filename must come before
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the command. The --recipient (-r) option takes a name or keyID to
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encrypt the message to, which must come right after the -r option.
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The --encrypt (or -e) command comes after all the options and is
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followed by the file you wish to encrypt. Therefore in this example
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the command-line issued would be:
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[H samp]
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$ gpg -r alice -o secret.txt -e test.txt
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[H /samp]
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If you write the options out in full, it is easier to read:
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[H samp]
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$ gpg --recipient alice --output secret.txt --encrypt test.txt
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[H /samp]
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If you're encrypting to a file with the extension ".txt", then you'd
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probably expect to see ASCII-armored text in the file (not binary),
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so you need to add the --armor (-a) option, which doesn't take any
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arguments:
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[H samp]
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$ gpg --armor --recipient alice --output secret.txt --encrypt test.txt
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[H /samp]
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If you imagine square brackets around the optional parts, it becomes
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a bit clearer:
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[H samp]
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$ gpg [--armor] [--recipient alice] [--output secret.txt] --encrypt test.txt
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[H /samp]
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The optional parts can be rearranged any way you want:
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[H samp]
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$ gpg --output secret.txt --recipient alice --armor --encrypt test.txt
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[H /samp]
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If your filename begins with a hyphen (e.g. "-a.txt"), GnuPG assumes
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this is an option and may complain. To avoid this you have to either
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use "./-a.txt", or stop the option and command processing with two
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hyphens: "-- -a.txt".
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[H B]The exception to using only one command:[H /B] signing and encrypting
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at the same time. For this you can combine both commands, such as in:
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[H samp]
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$ gpg [--options] --sign --encrypt foo.txt
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[H /samp]
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<Q> I can't delete a user ID on my secret keyring because it has
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already been deleted on my public keyring. What can I do?
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Because you can only select from the public key ring, there is no
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direct way to do this. However it is not very complicated to do
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anyway. Create a new user ID with exactly the same name and you
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will see that there are now two identical user IDs on the secret
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ring. Now select this user ID and delete it. Both user IDs will be
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removed from the secret ring.
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<Q> I can't delete my secret key because the public key disappeared.
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What can I do?
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To select a key a search is always done on the public keyring,
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therefore it is not possible to select a secret key without
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having the public key. Normally it should never happen that the
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public key got lost but the secret key is still available. The
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reality is different, so GnuPG implements a special way to deal
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with it: Simply use the long keyID to specify the key to delete,
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which can be obtained by using the --with-colons options (it is
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the fifth field in the lines beginning with "sec").
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If you've lost your public key and need to recreate it instead
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for continued use with your secret key, you may be able to use
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gpgsplit as detailed in question <Rgpgsplit>.
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<Q> What are trust, validity and ownertrust?
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With GnuPG, the term "ownertrust" is used instead of "trust" to
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help clarify that this is the value you have assigned to a key
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to express how much you trust the owner of this key to correctly
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sign (and thereby introduce) other keys. The "validity", or
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calculated trust, is a value which indicates how much GnuPG
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considers a key as being valid (that it really belongs to the
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one who claims to be the owner of the key). For more information
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on trust values see the chapter "The Web of Trust" in The GNU
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Privacy Handbook.
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<Q> How do I sign a patch file?
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Use "gpg --clearsign --not-dash-escaped ...". The problem with
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--clearsign is that all lines starting with a dash are quoted with
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"- "; obviously diff produces many lines starting with a dash and
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these are then quoted and that is not good for a patch ;-). To use
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a patch file without removing the cleartext signature, the special
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option --not-dash-escaped may be used to suppress generation of
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these escape sequences. You should not mail such a patch because
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spaces and line endings are also subject to the signature and a
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mailer may not preserve these. If you want to mail a file you can
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simply sign it using your MUA (Mail User Agent).
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<Q> Where is the "encrypt-to-self" option?
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Use "--encrypt-to your_keyID". You can use more than one of these
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options. To temporarily override the use of this additional key,
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you can use the option "--no-encrypt-to".
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<Q> How can I get rid of the Version and Comment headers in armored
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messages?
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Use "--no-version --comment ''". Note that the left over blank line
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is required by the protocol.
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<Q> What does the "You are using the xxxx character set." mean?
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This note is printed when UTF-8 mapping has to be done. Make sure
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that the displayed character set is the one you have activated on
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your system. Since "iso-8859-1" is the character set most used,
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this is the default. You can change the charset with the option
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"--charset". It is important that your active character set matches
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the one displayed - if not, restrict yourself to plain 7 bit ASCII
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and no mapping has to be done.
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<Q> How can I get list of key IDs used to encrypt a message?
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[H samp]
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$ gpg --batch --decrypt --list-only --status-fd 1 2>/dev/null |
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awk '/^\[GNUPG:\] ENC_TO / { print $3 }'
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[H /samp]
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<Q> Why can't I decrypt files encrypted as symmetrical-only (-c) with
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a version of GnuPG prior to 1.0.1.
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There was a bug in GnuPG versions prior to 1.0.1 which affected files
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only if 3DES or Twofish was used for symmetric-only encryption (this has
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never been the default). The bug has been fixed, but to enable decryption
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of old files you should run gpg with the option "--emulate-3des-s2k-bug",
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decrypt the file and encrypt it again without this option.
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NOTE: This option was removed in GnuPG development version 1.1.0 and later
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updates, so you will need to use a version between 1.0.1 and 1.0.7 to
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re-encrypt any affected files.
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<Q> How can I use GnuPG in an automated environment?
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You should use the option --batch and don't use passphrases as
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there is usually no way to store it more securely than on the
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secret keyring itself. The suggested way to create keys for an
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automated environment is:
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On a secure machine:
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[H ol]
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[H li] If you want to do automatic signing, create a signing subkey
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for your key (use the interactive key editing menu by issueing
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the command 'gpg --edit-key keyID', enter "addkey" and select
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the DSA key type).
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[H li] Make sure that you use a passphrase (needed by the current
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implementation).
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[H li] gpg --export-secret-subkeys --no-comment foo >secring.auto
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[H li] Copy secring.auto and the public keyring to a test directory.
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[H li] Change to this directory.
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[H li] gpg --homedir . --edit foo and use "passwd" to remove the
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passphrase from the subkeys. You may also want to remove all
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unused subkeys.
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[H li] Copy secring.auto to a floppy and carry it to the target box.
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[H /ol]
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On the target machine:
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[H ol]
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[H li] Install secring.auto as the secret keyring.
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[H li] Now you can start your new service. It's also a good idea to
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install an intrusion detection system so that you hopefully
474
get a notice of an successful intrusion, so that you in turn
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can revoke all the subkeys installed on that machine and
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install new subkeys.
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[H /ol]
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<Q> Which email-client can I use with GnuPG?
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Using GnuPG to encrypt email is one of the most popular uses.
482
Several mail clients or mail user agents (MUAs) support GnuPG to
483
varying degrees. Simplifying a bit, there are two ways mail can be
484
encrypted with GnuPG: the "old style" ASCII armor (i.e. cleartext
485
encryption), and RFC 2015 style (previously PGP/MIME, now OpenPGP).
486
The latter has full MIME support. Some MUAs support only one of
487
them, so whichever you actually use depends on your needs as well
488
as the capabilities of your addressee. As well, support may be
489
native to the MUA, or provided via "plug-ins" or external tools.
490
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The following list is not exhaustive:
492
493
[H pre]
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MUA OpenPGP ASCII How? (N,P,T)
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-------------------------------------------------------------
496
Calypso N Y P (Unixmail)
497
Elm N Y T (mailpgp,morepgp)
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Elm ME+ N Y N
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Emacs/Gnus Y Y T (Mailcrypt,gpg.el)
500
Emacs/Mew Y Y N
501
Emacs/VM N Y T (Mailcrypt)
502
Evolution Y Y N
503
Exmh Y Y N
504
GNUMail.app Y Y P (PGPBundle)
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GPGMail Y Y N
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KMail (<=1.4.x) N Y N
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KMail (1.5.x) Y(P) Y(N) P/N
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Mozilla Y Y P (Enigmail)
509
Mulberry Y Y P
510
Mutt Y Y N
511
Sylpheed Y Y N
512
Claws-mail Y Y N
513
TkRat Y Y N
514
XEmacs/Gnus Y Y T (Mailcrypt)
515
XEmacs/Mew Y Y N
516
XEmacs/VM N Y T (Mailcrypt)
517
XFmail Y Y N
518
519
N - Native, P - Plug-in, T - External Tool
520
[H /pre]
521
522
The following table lists proprietary MUAs. The GNU Project
523
suggests against the use of these programs, but they are listed
524
for interoperability reasons for your convenience.
525
526
[H pre]
527
MUA OpenPGP ASCII How? (N,P,T)
528
-------------------------------------------------------------
529
Apple Mail Y Y P (GPGMail)
530
Becky2 Y Y P (BkGnuPG)
531
Eudora Y Y P (EuroraGPG)
532
Eudora Pro Y Y P (EudoraGPG)
533
Lotus Notes N Y P
534
Netscape 4.x N Y P
535
Netscape 7.x Y Y P (Enigmail)
536
Novell Groupwise N Y P
537
Outlook N Y P (G-Data)
538
Outlook Express N Y P (GPGOE)
539
Pegasus N Y P (QDPGP,PM-PGP)
540
Pine N Y T (pgpenvelope,(gpg|pgp)4pine)
541
Postme N Y P (GPGPPL)
542
The Bat! N Y P (Ritlabs)
543
[H /pre]
544
545
Good overviews of OpenPGP-support can be found at:[H br]
546
[H a href=http://www.openpgp.fr.st/courrier_en.html]<http://www.openpgp.fr.st/courrier_en.html>[H /a] and[H br]
547
[H a href=http://www.bretschneidernet.de/tips/secmua.html]<http://www.bretschneidernet.de/tips/secmua.html>[H /a].
548
549
Users of Win32 MUAs that lack OpenPGP support may look into
550
using GPGrelay [H a href=http://gpgrelay.sourceforge.net]<http://gpgrelay.sourceforge.net>[H /a], a small
551
email-relaying server that uses GnuPG to enable many email clients
552
to send and receive emails that conform to PGP-MIME (RFC 2015).
553
554
<Q> Can't we have a gpg library?
555
556
This has been frequently requested. However, the current viewpoint
557
of the GnuPG maintainers is that this would lead to several security
558
issues and will therefore not be implemented in the foreseeable
559
future. However, for some areas of application gpgme could do the
560
trick. You'll find it at [H a href=[$hGPGFTP]/gcrypt/alpha/gpgme]<[$hGPGFTP]/gcrypt/alpha/gpgme>[H /a].
561
562
<Q> I have successfully generated a revocation certificate, but I don't
563
understand how to send it to the key servers.
564
565
Most keyservers don't accept a 'bare' revocation certificate. You
566
have to import the certificate into gpg first:
567
568
[H samp]
569
$ gpg --import my-revocation.asc
570
[H /samp]
571
572
then send the revoked key to the keyservers:
573
574
[H samp]
575
$ gpg --keyserver certserver.pgp.com --send-keys mykeyid
576
[H /samp]
577
578
(or use a keyserver web interface for this).
579
580
<Dhomedir>
581
<Q> How do I put my keyring in a different directory?
582
583
GnuPG keeps several files in a special homedir directory. These
584
include the options file, pubring.gpg, secring.gpg, trustdb.gpg,
585
and others. GnuPG will always create and use these files. On unices,
586
the homedir is usually ~/.gnupg; on Windows it is name "gnupg" and
587
found below the user's application directory. Run the gpg and
588
pass the option --version to see the name of that directory.
589
590
If you want to put your keyrings somewhere else, use the option:
591
592
[H samp]
593
--homedir /my/path/
594
[H /samp]
595
596
to make GnuPG create all its files in that directory. Your keyring
597
will be "/my/path/pubring.gpg". This way you can store your secrets
598
on a floppy disk. Don't use "--keyring" as its purpose is to specify
599
additional keyring files.
600
601
<Q> How do I verify signed packages?
602
603
Before you can verify the signature that accompanies a package,
604
you must first have the vendor, organisation, or issueing person's
605
key imported into your public keyring. To prevent GnuPG warning
606
messages the key should also be validated (or locally signed).
607
608
You will also need to download the detached signature file along
609
with the package. These files will usually have the same name as
610
the package, with either a binary (.sig) or ASCII armor (.asc)
611
extension.
612
613
Once their key has been imported, and the package and accompanying
614
signature files have been downloaded, use:
615
616
[H samp]
617
$ gpg --verify sigfile signed-file
618
[H /samp]
619
620
If the signature file has the same base name as the package file,
621
the package can also be verified by specifying just the signature
622
file, as GnuPG will derive the package's file name from the name
623
given (less the .sig or .asc extension). For example, to verify a
624
package named foobar.tar.gz against its detached binary signature
625
file, use:
626
627
[H samp]
628
$ gpg --verify foobar.tar.gz.sig
629
[H /samp]
630
631
<Q> How do I export a keyring with only selected signatures (keys)?
632
633
If you're wanting to create a keyring with only a subset of keys
634
selected from a master keyring (for a club, user group, or company
635
department for example), simply specify the keys you want to export:
636
637
[H samp]
638
$ gpg --armor --export key1 key2 key3 key4 > keys1-4.asc
639
[H /samp]
640
641
<Dgpgsplit>
642
<Q> I still have my secret key, but lost my public key. What can I do?
643
644
All OpenPGP secret keys have a copy of the public key inside them,
645
and in a worst-case scenario, you can create yourself a new public
646
key using the secret key.
647
648
A tool to convert a secret key into a public one has been included
649
(it's actually a new option for gpgsplit) and is available with GnuPG
650
versions 1.2.1 or later (or can be found in CVS). It works like this:
651
652
[H samp]
653
$ gpgsplit --no-split --secret-to-public secret.gpg >publickey.gpg
654
[H /samp]
655
656
One should first try to export the secret key and convert just this
657
one. Using the entire secret keyring should work too. After this has
658
been done, the publickey.gpg file can be imported into GnuPG as usual.
659
660
<Q> Clearsigned messages sent from my web-mail account have an invalid
661
signature. Why?
662
663
Check to make sure the settings for your web-based email account
664
do not use HTML formatting for the pasted clearsigned message. This can
665
alter the message with embedded HTML markup tags or spaces, resulting
666
in an invalid signature. The recipient may be able to copy the signed
667
message block to a text file for verification, or the web email
668
service may allow you to attach the clearsigned message as a file
669
if plaintext messages are not an option.
670
671
672
<S> COMPATIBILITY ISSUES
673
674
<Dcompat>
675
<Q> How can I encrypt a message with GnuPG so that PGP is able to decrypt it?
676
677
It depends on the PGP version.
678
679
[H ul]
680
[H li]PGP 2.x[H br]
681
You can't do that because PGP 2.x normally uses IDEA which is not
682
supported by GnuPG as it is patented (see <Ridea>), but if you have a
683
modified version of PGP you can try this:
684
685
[H samp]
686
$ gpg --rfc1991 --cipher-algo 3des ...
687
[H /samp]
688
689
Please don't pipe the data to encrypt to gpg but provide it using a
690
filename; otherwise, PGP 2 will not be able to handle it.
691
692
As for conventional encryption, you can't do this for PGP 2.
693
694
[H li]PGP 5.x and higher[H br]
695
You need to provide two additional options:
696
697
[H samp]
698
--compress-algo 1 --cipher-algo cast5
699
[H /samp]
700
701
You may also use "3des" instead of "cast5", and "blowfish" does not
702
work with all versions of PGP 5. You may also want to put:
703
704
[H samp]
705
compress-algo 1
706
[H /samp]
707
708
into your ~/.gnupg/options file - this does not affect normal GnuPG
709
operation.
710
711
This applies to conventional encryption as well.
712
[H /UL]
713
714
<Q> How do I migrate from PGP 2.x to GnuPG?
715
716
PGP 2 uses the RSA and IDEA encryption algorithms. Whereas the RSA
717
patent has expired and RSA is included as of GnuPG 1.0.3, the IDEA
718
algorithm is still patented until 2007. Under certain conditions you
719
may use IDEA even today. In that case, you may refer to Question
720
<Ridea> about how to add IDEA support to GnuPG and read
721
[H a href=[$hGPGHTTP]/gph/en/pgp2x.html]<[$hGPGHTTP]/gph/en/pgp2x.html>[H /a] to perform the migration.
722
723
<Q> (removed)
724
725
(empty)
726
727
<Q> Why is PGP 5.x not able to encrypt messages with some keys?
728
729
PGP, Inc. refuses to accept Elgamal keys of type 20 even for
730
encryption. They only support type 16 (which is identical at least
731
for decryption). To be more inter-operable, GnuPG (starting with
732
version 0.3.3) now also uses type 16 for the Elgamal subkey which is
733
created if the default key algorithm is chosen. You may add a type
734
16 Elgamal key to your public key, which is easy as your key
735
signatures are still valid.
736
737
<Q> Why is PGP 5.x not able to verify my messages?
738
739
PGP 5.x does not accept v4 signatures for data material but OpenPGP
740
requests generation of v4 signatures for all kind of data, that's why
741
GnuPG defaults to them. Use the option "--force-v3-sigs" to generate
742
v3 signatures for data.
743
744
<Q> How do I transfer owner trust values from PGP to GnuPG?
745
746
There is a script in the tools directory to help you. After you have
747
imported the PGP keyring you can give this command:
748
749
[H samp]
750
$ lspgpot pgpkeyring | gpg --import-ownertrust
751
[H /samp]
752
753
where pgpkeyring is the original keyring and not the GnuPG keyring
754
you might have created in the first step.
755
756
<Q> PGP does not like my secret key.
757
758
Older PGPs probably bail out on some private comment packets used by
759
GnuPG. These packets are fully in compliance with OpenPGP; however
760
PGP is not really OpenPGP aware. A workaround is to export the
761
secret keys with this command:
762
763
[H samp]
764
$ gpg --export-secret-keys --no-comment -a your-KeyID
765
[H /samp]
766
767
Another possibility is this: by default, GnuPG encrypts your secret
768
key using the Blowfish symmetric algorithm. Older PGPs will only
769
understand 3DES, CAST5, or IDEA symmetric algorithms. Using the
770
following method you can re-encrypt your secret gpg key with a
771
different algo:
772
773
[H samp]
774
$ gpg --s2k-cipher-algo=CAST5 --s2k-digest-algo=SHA1
775
--compress-algo=1 --edit-key <username>
776
[H /samp]
777
778
Then use passwd to change the password (just change it to the same
779
thing, but it will encrypt the key with CAST5 this time).
780
781
Now you can export it and PGP should be able to handle it.
782
783
For PGP 6.x the following options work to export a key:
784
785
[H samp]
786
$ gpg --s2k-cipher-algo 3des --compress-algo 1 --rfc1991
787
--export-secret-keys <KeyID>
788
[H /samp]
789
790
<Doptions>
791
<Q> GnuPG no longer installs a ~/.gnupg/options file. Is it missing?
792
793
No. The ~/.gnupg/options file has been renamed to ~/.gnupg/gpg.conf for
794
new installs as of version 1.1.92. If an existing ~/.gnupg/options file
795
is found during an upgrade it will still be used, but this change was
796
required to have a more consistent naming scheme with forthcoming tools.
797
An existing options file can be renamed to gpg.conf for users upgrading,
798
or receiving the message that the "old default options file" is ignored
799
(occurs if both a gpg.conf and an options file are found).
800
801
<Q> How do you export GnuPG keys for use with PGP?
802
803
This has come up fairly often, so here's the HOWTO:
804
805
PGP can (for most key types) use secret keys generated by GnuPG. The
806
problems that come up occasionally are generally because GnuPG
807
supports a few more features from the OpenPGP standard than PGP does.
808
If your secret key has any of those features in use, then PGP will
809
reject the key or you will have problems communicating later. Note
810
that PGP doesn't do Elgamal signing keys at all, so they are not
811
usable with any version.
812
813
These instructions should work for GnuPG 1.0.7 and later, and PGP
814
7.0.3 and later.
815
816
Start by editing the key. Most of this line is not really necessary
817
as the default values are correct, but it does not hurt to repeat the
818
values, as this will override them in case you have something else set
819
in your options file.
820
821
[H samp]
822
$ gpg --s2k-cipher-algo cast5 --s2k-digest-algo sha1 --s2k-mode 3
823
--simple-sk-checksum --edit KeyID
824
[H /samp]
825
826
Turn off some features. Set the list of preferred ciphers, hashes,
827
and compression algorithms to things that PGP can handle. (Yes, I
828
know this is an odd list of ciphers, but this is what PGP itself uses,
829
minus IDEA).
830
831
[H samp]
832
> setpref S9 S8 S7 S3 S2 S10 H2 H3 Z1 Z0
833
[H /samp]
834
835
Now put the list of preferences onto the key.
836
837
[H samp]
838
> updpref
839
[H /samp]
840
841
Finally we must decrypt and re-encrypt the key, making sure that we
842
encrypt with a cipher that PGP likes. We set this up in the --edit
843
line above, so now we just need to change the passphrase to make it
844
take effect. You can use the same passphrase if you like, or take
845
this opportunity to actually change it.
846
847
[H samp]
848
> passwd
849
[H /samp]
850
851
Save our work.
852
853
[H samp]
854
> save
855
[H /samp]
856
857
Now we can do the usual export:
858
859
[H samp]
860
$ gpg --export KeyID > mypublickey.pgp[H br]
861
$ gpg --export-secret-key KeyID > mysecretkey.pgp
862
[H /samp]
863
864
Thanks to David Shaw for this information!
865
866
867
<S> PROBLEMS and ERROR MESSAGES
868
869
<Q> Why do I get "gpg: Warning: using insecure memory!"
870
871
On many systems this program should be installed as setuid(root).
872
This is necessary to lock memory pages. Locking memory pages prevents
873
the operating system from writing them to disk and thereby keeping your
874
secret keys really secret. If you get no warning message about insecure
875
memory your operating system supports locking without being root. The
876
program drops root privileges as soon as locked memory is allocated.
877
878
To setuid(root) permissions on the gpg binary you can either use:
879
880
[H samp]
881
$ chmod u+s /path/to/gpg
882
[H /samp]
883
884
or
885
886
[H samp]
887
$ chmod 4755 /path/to/gpg
888
[H /samp]
889
890
Some refrain from using setuid(root) unless absolutely required for
891
security reasons. Please check with your system administrator if you
892
are not able to make these determinations yourself.
893
894
On UnixWare 2.x and 7.x you should install GnuPG with the 'plock'
895
privilege to get the same effect:
896
897
[H samp]
898
$ filepriv -f plock /path/to/gpg
899
[H /samp]
900
901
If you can't or don't want to install GnuPG setuid(root), you can
902
use the option "--no-secmem-warning" or put:
903
904
[H samp]
905
no-secmem-warning
906
[H /samp]
907
908
in your ~/.gnupg/options or ~/.gnupg/gpg.conf file (this disables
909
the warning).
910
911
On some systems (e.g., Windows) GnuPG does not lock memory pages
912
and older GnuPG versions (<=1.0.4) issue the warning:
913
914
[H samp]
915
gpg: Please note that you don't have secure memory
916
[H /samp]
917
918
This warning can't be switched off by the above option because it
919
was thought to be too serious an issue. However, it confused users
920
too much, so the warning was eventually removed.
921
922
<Q> Large File Support doesn't work ...
923
924
LFS works correctly in post-1.0.4 versions. If configure doesn't
925
detect it, try a different (i.e., better) compiler. egcs 1.1.2 works
926
fine, other gccs sometimes don't. BTW, several compilation problems
927
of GnuPG 1.0.3 and 1.0.4 on HP-UX and Solaris were due to broken LFS
928
support.
929
930
<Q> In the edit menu the trust values are not displayed correctly after
931
signing uids. Why?
932
933
This happens because some information is stored immediately in
934
the trustdb, but the actual trust calculation can be done after the
935
save command. This is a "not easy to fix" design bug which will be
936
addressed in some future release.
937
938
<Q> What does "skipping pubkey 1: already loaded" mean?
939
940
As of GnuPG 1.0.3, the RSA algorithm is included. If you still have
941
a "load-extension rsa" in your options file, the above message
942
occurs. Just remove the load command from the options file.
943
944
<Q> GnuPG 1.0.4 doesn't create ~/.gnupg ...
945
946
That's a known bug, already fixed in newer versions.
947
948
<Q> An Elgamal signature does not verify anymore since version 1.0.2 ...
949
950
Use the option --emulate-md-encode-bug.
951
952
<Q> Old versions of GnuPG can't verify Elgamal signatures
953
954
Update to GnuPG 1.0.2 or newer.
955
956
<Q> When I use --clearsign, the plain text has sometimes extra dashes
957
in it - why?
958
959
This is called dash-escaped text and is required by OpenPGP.
960
It always happens when a line starts with a dash ("-") and is
961
needed to make the lines that structure signature and text
962
(i.e., "-----BEGIN PGP SIGNATURE-----") to be the only lines
963
that start with two dashes.
964
965
If you use GnuPG to process those messages, the extra dashes
966
are removed. Good mail clients remove those extra dashes when
967
displaying such a message.
968
969
<Q> What is the thing with "can't handle multiple signatures"?
970
971
Due to different message formats GnuPG is not always able to split
972
a file with multiple signatures unambiguously into its parts. This
973
error message informs you that there is something wrong with the input.
974
975
The only way to have multiple signatures in a file is by using the
976
OpenPGP format with one-pass-signature packets (which is GnuPG's
977
default) or the cleartext signed format.
978
979
<Q> If I submit a key to a keyserver, nothing happens ...
980
981
You are most likely using GnuPG 1.0.2 or older on Windows. That's
982
feature isn't yet implemented, but it's a bug not to say it. Newer
983
versions issue a warning. Upgrade to 1.4.5 or newer.
984
985
<Q> I get "gpg: waiting for lock ..."
986
987
A previous instance of gpg has most likely exited abnormally and left
988
a lock file. Go to ~/.gnupg and look for .*.lock files and remove them.
989
990
<Q> Older gpg binaries (e.g., 1.0) have problems with keys from newer
991
gpg binaries ...
992
993
As of 1.0.3, keys generated with gpg are created with preferences to
994
TWOFISH (and AES since 1.0.4) and that also means that they have the
995
capability to use the new MDC encryption method. This will go into
996
OpenPGP soon, and is also suppoted by PGP 7. This new method avoids
997
a (not so new) attack on all email encryption systems.
998
999
This in turn means that pre-1.0.3 gpg binaries have problems with
1000
newer keys. Because of security and bug fixes, you should keep your
1001
GnuPG installation in a recent state anyway. As a workaround, you can
1002
force gpg to use a previous default cipher algo by putting:
1003
1004
[H samp]
1005
cipher-algo cast5
1006
[H /samp]
1007
1008
into your options file.
1009
1010
<Q> With 1.0.4, I get "this cipher algorithm is deprecated ..."
1011
1012
If you just generated a new key and get this message while
1013
encrypting, you've witnessed a bug in 1.0.4. It uses the new AES
1014
cipher Rijndael that is incorrectly being referred as "deprecated".
1015
Ignore this warning, more recent versions of gpg are corrected.
1016
1017
<Q> Some dates are displayed as ????-??-??. Why?
1018
1019
Due to constraints in most libc implementations, dates beyond
1020
2038-01-19 can't be displayed correctly. 64-bit OSes are not
1021
affected by this problem. To avoid printing wrong dates, GnuPG
1022
instead prints some question marks. To see the correct value, you
1023
can use the options --with-colons and --fixed-list-mode.
1024
1025
<Q> I still have a problem. How do I report a bug?
1026
1027
Are you sure that it's not been mentioned somewhere on the mailing
1028
lists? Did you have a look at the bug list (you'll find a link to
1029
the list of reported bugs on the documentation page). If you're not
1030
sure about it being a bug, you can send mail to the gnupg-devel
1031
list. Otherwise, use the bug tracking system
1032
[H a href=http://bugs.gnupg.org]<http://bugs.gnupg.org>[H /a].
1033
1034
<Q> Why doesn't GnuPG support X.509 certificates?
1035
1036
GnuPG, first and foremost, is an implementation of the OpenPGP
1037
standard (RFC 2440), which is a competing infrastructure, different
1038
from X.509.
1039
1040
They are both public-key cryptosystems, but how the public keys are
1041
actually handled is different.
1042
1043
<Q> Why do national characters in my user ID look funny?
1044
1045
According to OpenPGP, GnuPG encodes user ID strings (and other
1046
things) using UTF-8. In this encoding of Unicode, most national
1047
characters get encoded as two- or three-byte sequences. For
1048
example, å (0xE5 in ISO-8859-1) becomes Ã¥ (0xC3,
1049
0xA5). This might also be the reason why keyservers can't find
1050
your key.
1051
1052
<Q> I get 'sed' errors when running ./configure on Mac OS X ...
1053
1054
This will be fixed after GnuPG has been upgraded to autoconf-2.50.
1055
Until then, find the line setting CDPATH in the configure script
1056
and place an:
1057
1058
[H samp]
1059
unset CDPATH
1060
[H /samp]
1061
1062
statement below it.
1063
1064
<Q> Why does GnuPG 1.0.6 bail out on keyrings used with 1.0.7?
1065
1066
There is a small bug in 1.0.6 which didn't parse trust packets
1067
correctly. You may want to apply this patch if you can't upgrade:
1068
1069
[H a href=http://www.gnupg.org/developer/gpg-woody-fix.txt]<http://www.gnupg.org/developer/gpg-woody-fix.txt>[H /a]
1070
1071
<Q> I upgraded to GnuPG version 1.0.7 and now it takes longer to load my
1072
keyrings. What can I do?
1073
1074
The way signature states are stored has changed so that v3 signatures
1075
can be supported. You can use the new --rebuild-keydb-caches migration
1076
command, which was built into this release and increases the speed of
1077
many operations for existing keyrings.
1078
1079
<Q> Doesn't a fully trusted user ID on a key prevent warning messages
1080
when encrypting to other IDs on the key?
1081
1082
No. That was actually a key validity bug in GnuPG 1.2.1 and earlier
1083
versions. As part of the development of GnuPG 1.2.2, a bug was
1084
discovered in the key validation code. This bug causes keys with
1085
more than one user ID to give all user IDs on the key the amount of
1086
validity given to the most-valid key. The bug has been fixed in GnuPG
1087
release 1.2.2, and upgrading is the recommended fix for this problem.
1088
More information and a patch for a some pre-1.2.2 versions of GnuPG
1089
can be found at:
1090
1091
[H a href=http://lists.gnupg.org/pipermail/gnupg-announce/2003q2/000268.html]<http://lists.gnupg.org/pipermail/gnupg-announce/2003q2/000268.html>[H /a]
1092
1093
<Q> I just compiled GnuPG from source on my GNU/Linux RPM-based system
1094
and it's not working. Why?
1095
1096
Many GNU/Linux distributions that are RPM-based will install a
1097
version of GnuPG as part of its standard installation, placing the
1098
binaries in the /usr/bin directory. Later, compiling and installing
1099
GnuPG from source other than from a source RPM won't normally
1100
overwrite these files, as the default location for placement of
1101
GnuPG binaries is in /usr/local/bin unless the '--prefix' switch
1102
is used during compile to specify an alternate location. Since the
1103
/usr/bin directory more than likely appears in your path before
1104
/usr/local/bin, the older RPM-version binaries will continue to
1105
be used when called since they were not replaced.
1106
1107
To resolve this, uninstall the RPM-based version with 'rpm -e gnupg'
1108
before installing the binaries compiled from source. If dependency
1109
errors are displayed when attempting to uninstall the RPM (such as
1110
when Red Hat's up2date is also installed, which uses GnuPG), uninstall
1111
the RPM with 'rpm -e gnupg --nodeps' to force the uninstall. Any
1112
dependent files should be automatically replaced during the install
1113
of the compiled version. If the default /usr/local/bin directory is
1114
used, some packages such as SuSE's Yast Online Update may need to be
1115
configured to look for GnuPG binaries in the /usr/local/bin directory,
1116
or symlinks can be created in /usr/bin that point to the binaries
1117
located in /usr/local/bin.
1118
1119
1120
<S> ADVANCED TOPICS
1121
1122
<Q> How does this whole thing work?
1123
1124
To generate a secret/public keypair, run:
1125
1126
[H samp]
1127
$ gpg --gen-key
1128
[H /samp]
1129
1130
and choose the default values.
1131
1132
Data that is encrypted with a public key can only be decrypted by
1133
the matching secret key. The secret key is protected by a password,
1134
the public key is not.
1135
1136
So to send your friend a message, you would encrypt your message
1137
with his public key, and he would only be able to decrypt it by
1138
having the secret key and putting in the password to use his secret
1139
key.
1140
1141
GnuPG is also useful for signing things. Files that are encrypted
1142
with the secret key can be decrypted with the public key. To sign
1143
something, a hash is taken of the data, and then the hash is in some
1144
form encoded with the secret key. If someone has your public key, they
1145
can verify that it is from you and that it hasn't changed by checking
1146
the encoded form of the hash with the public key.
1147
1148
A keyring is just a large file that stores keys. You have a public
1149
keyring where you store yours and your friend's public keys. You have
1150
a secret keyring that you keep your secret key on, and should be very
1151
careful with. Never ever give anyone else access to it and use a *good*
1152
passphrase to protect the data in it.
1153
1154
You can 'conventionally' encrypt something by using the option 'gpg -c'.
1155
It is encrypted using a passphrase, and does not use public and secret
1156
keys. If the person you send the data to knows that passphrase, they
1157
can decrypt it. This is usually most useful for encrypting things to
1158
yourself, although you can encrypt things to your own public key in the
1159
same way. It should be used for communication with partners you know
1160
and where it is easy to exchange the passphrases (e.g. with your boy
1161
friend or your wife). The advantage is that you can change the
1162
passphrase from time to time and decrease the risk, that many old
1163
messages may be decrypted by people who accidently got your passphrase.
1164
1165
You can add and copy keys to and from your keyring with the 'gpg
1166
--import' and 'gpg --export' command. 'gpg --export-secret-keys' will
1167
export secret keys. This is normally not useful, but you can generate
1168
the key on one machine then move it to another machine.
1169
1170
Keys can be signed under the 'gpg --edit-key' option. When you sign a
1171
key, you are saying that you are certain that the key belongs to the
1172
person it says it comes from. You should be very sure that is really
1173
that person: You should verify the key fingerprint with:
1174
1175
[H samp]
1176
$ gpg --fingerprint KeyID
1177
[H /samp]
1178
1179
over the phone (if you really know the voice of the other person), at
1180
a key signing party (which are often held at computer conferences),
1181
or at a meeting of your local GNU/Linux User Group.
1182
1183
Hmm, what else. You may use the option '-o filename' to force output
1184
to this filename (use '-' to force output to stdout). '-r' just lets
1185
you specify the recipient (which public key you encrypt with) on the
1186
command line instead of typing it interactively.
1187
1188
Oh yeah, this is important. By default all data is encrypted in some
1189
weird binary format. If you want to have things appear in ASCII text
1190
that is readable, just add the '-a' option. But the preferred method
1191
is to use a MIME aware mail reader (Mutt, Pine and many more).
1192
1193
There is a small security glitch in the OpenPGP (and therefore GnuPG)
1194
system; to avoid this you should always sign and encrypt a message
1195
instead of only encrypting it.
1196
1197
<Q> Why are some signatures with an ELG-E key valid?
1198
1199
These are Elgamal keys generated by GnuPG in v3 (RFC 1991) packets.
1200
The OpenPGP draft later changed the algorithm identifier for Elgamal
1201
keys which are usable for signatures and encryption from 16 to 20.
1202
GnuPG now uses 20 when it generates new Elgamal keys but still
1203
accepts 16 (which is according to OpenPGP "encryption only") if this
1204
key is in a v3 packet. GnuPG is the only program which had used
1205
these v3 Elgamal keys - so this assumption is quite safe.
1206
1207
<Q> How does the whole trust thing work?
1208
1209
It works more or less like PGP. The difference is that the trust is
1210
computed at the time it is needed. This is one of the reasons for
1211
the trustdb which holds a list of valid key signatures. If you are
1212
not running in batch mode you will be asked to assign a trust
1213
parameter (ownertrust) to a key.
1214
1215
You can see the validity (calculated trust value) using this
1216
command.
1217
1218
[H samp]
1219
$ gpg --list-keys --with-colons
1220
[H /samp]
1221
1222
If the first field is "pub" or "uid", the second field shows you the
1223
trust:
1224
1225
[H pre]
1226
o = Unknown (this key is new to the system)
1227
e = The key has expired
1228
q = Undefined (no value assigned)
1229
n = Don't trust this key at all
1230
m = There is marginal trust in this key
1231
f = The key is full trusted
1232
u = The key is ultimately trusted; this is only used
1233
for keys for which the secret key is also available.
1234
r = The key has been revoked
1235
d = The key has been disabled
1236
[H /pre]
1237
1238
The value in the "pub" record is the best one of all "uid" records.
1239
You can get a list of the assigned trust values (how much you trust
1240
the owner to correctly sign another person's key) with:
1241
1242
[H samp]
1243
$ gpg --list-ownertrust
1244
[H /samp]
1245
1246
The first field is the fingerprint of the primary key, the second
1247
field is the assigned value:
1248
1249
[H pre]
1250
- = No ownertrust value yet assigned or calculated.
1251
n = Never trust this keyholder to correctly verify others signatures.
1252
m = Have marginal trust in the keyholders capability to sign other
1253
keys.
1254
f = Assume that the key holder really knows how to sign keys.
1255
u = No need to trust ourself because we have the secret key.
1256
[H /pre]
1257
1258
Keep these values confidential because they express your opinions
1259
about others. PGP stores this information with the keyring thus it
1260
is not a good idea to publish a PGP keyring instead of exporting the
1261
keyring. GnuPG stores the trust in the trustdb.gpg file so it is okay
1262
to give a gpg keyring away (but we have a --export command too).
1263
1264
<Q> What kind of output is this: "key C26EE891.298, uid 09FB: ...."?
1265
1266
This is the internal representation of a user ID in the trustdb.
1267
"C26EE891" is the keyid, "298" is the local ID (a record number in
1268
the trustdb) and "09FB" is the last two bytes of a ripe-md-160 hash
1269
of the user ID for this key.
1270
1271
<Q> How do I interpret some of the informational outputs?
1272
1273
While checking the validity of a key, GnuPG sometimes prints some
1274
information which is prefixed with information about the checked
1275
item.
1276
1277
[H samp]
1278
"key 12345678.3456"
1279
[H /samp]
1280
1281
This is about the key with key ID 12345678 and the internal number
1282
3456, which is the record number of the so called directory record
1283
in the trustdb.
1284
1285
[H samp]
1286
"uid 12345678.3456/ACDE"
1287
[H /samp]
1288
1289
This is about the user ID for the same key. To identify the user ID
1290
the last two bytes of a ripe-md-160 over the user ID ring is printed.
1291
1292
[H samp]
1293
"sig 12345678.3456/ACDE/9A8B7C6D"
1294
[H /samp]
1295
1296
This is about the signature with key ID 9A8B7C6D for the above key
1297
and user ID, if it is a signature which is direct on a key, the user
1298
ID part is empty (..//..).
1299
1300
<Q> Are the header lines of a cleartext signature part of the signed
1301
material?
1302
1303
No. For example you can add or remove "Comment:" lines. They have
1304
a purpose like the mail header lines. However a "Hash:" line is
1305
needed for OpenPGP signatures to tell the parser which hash
1306
algorithm to use.
1307
1308
<Q> What is the list of preferred algorithms?
1309
1310
The list of preferred algorithms is a list of cipher, hash and
1311
compression algorithms stored in the self-signature of a key during
1312
key generation. When you encrypt a document, GnuPG uses this list
1313
(which is then part of a public key) to determine which algorithms
1314
to use. Basically it tells other people what algorithms the
1315
recipient is able to handle and provides an order of preference.
1316
1317
<Q> How do I change the list of preferred algorithms?
1318
1319
In version 1.0.7 or later, you can use the edit menu and set the
1320
new list of preference using the command "setpref"; the format of
1321
this command resembles the output of the command "pref". The
1322
preference is not changed immediately but the set preference will
1323
be used when a new user ID is created. If you want to update the
1324
preferences for existing user IDs, select those user IDs (or select
1325
none to update all) and enter the command "updpref". Note that the
1326
timestamp of the self-signature is increased by one second when
1327
running this command.
1328
1329
<Q> How can I import all the missing signer keys?
1330
1331
If you imported a key and you want to also import all the signer's
1332
keys, you can do this with this command:
1333
1334
gpg --check-sigs --with-colon KEYID \
1335
| awk -F: '$1 == "sig" && $2 == "?" { print $5 }' \
1336
| sort | uniq | xargs echo gpg --recv-keys
1337
1338
Note that the invocation of sort is also required to wait for the
1339
of the listing before before starting the import.
1340
1341
1342
<S> ACKNOWLEDGEMENTS
1343
1344
Many thanks to Nils Ellmenreich for maintaining this FAQ file for
1345
such a long time, Werner Koch for the original FAQ file, and to all
1346
posters to gnupg-users and gnupg-devel. They all provided most of
1347
the answers.
1348
1349
Also thanks to Casper Dik for providing us with a script to generate
1350
this FAQ (he uses it for the excellent Solaris2 FAQ).
1351
1352
[H hr]
1353
1354
Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.,
1355
51 Franklin Street, Fifth Floor, Boston, MA 02111, USA
1356
1357
Verbatim copying and distribution of this entire article is permitted in
1358
any medium, provided this notice is preserved.
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