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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
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1
GnuPG Frequently Asked Questions
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Version: 1.6.3
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Last-Modified: Jul 30, 2003
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Maintained-by: David D. Scribner, <faq 'at' gnupg.org>
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This is the GnuPG FAQ. The latest HTML version is available
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here. <http://www.gnupg.org/documentation/faqs.html>
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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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1. GENERAL
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1.1) What is GnuPG?
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1.2) Is GnuPG compatible with PGP?
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1.3) Is GnuPG free to use for personal or commercial use?
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1.4) What conventions are used in this FAQ?
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2. SOURCES of INFORMATION
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2.1) Where can I find more information on GnuPG?
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2.2) Where do I get GnuPG?
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3. INSTALLATION
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3.1) Which OSes does GnuPG run on?
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3.2) Which random data gatherer should I use?
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3.3) How do I include support for RSA and IDEA?
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4. USAGE
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4.1) What is the recommended key size?
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4.2) Why does it sometimes take so long to create keys?
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4.3) And it really takes long when I work on a remote system. Why?
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4.4) What is the difference between options and commands?
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4.5) 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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4.6) I can't delete my secret key because the public key disappeared.
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What can I do?
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4.7) What are trust, validity and ownertrust?
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4.8) How do I sign a patch file?
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4.9) Where is the "encrypt-to-self" option?
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4.10) How can I get rid of the Version and Comment headers in armored
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messages?
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4.11) What does the "You are using the xxxx character set." mean?
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4.12) How can I get list of key IDs used to encrypt a message?
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4.13) 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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4.14) How can I use GnuPG in an automated environment?
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4.15) Which email-client can I use with GnuPG?
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4.16) Can't we have a gpg library?
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4.17) I have successfully generated a revocation certificate, but I don't
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understand how to send it to the key servers.
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4.18) How do I put my keyring in a different directory?
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4.19) How do I verify signed packages?
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4.20) How do I export a keyring with only selected signatures (keys)?
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4.21) I still have my secret key, but lost my public key. What can I do?
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4.22) Clearsigned messages sent from my web-mail account have an invalid
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signature. Why?
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5. COMPATIBILITY ISSUES
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5.1) How can I encrypt a message with GnuPG so that PGP is able to decrypt it?
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5.2) How do I migrate from PGP 2.x to GnuPG?
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5.3) (removed)
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5.4) Why is PGP 5.x not able to encrypt messages with some keys?
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5.5) Why is PGP 5.x not able to verify my messages?
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5.6) How do I transfer owner trust values from PGP to GnuPG?
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5.7) PGP does not like my secret key.
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5.8) GnuPG no longer installs a ~/.gnupg/options file. Is it missing?
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5.9) How do you export GnuPG keys for use with PGP?
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6. PROBLEMS and ERROR MESSAGES
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6.1) Why do I get "gpg: Warning: using insecure memory!"
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6.2) Large File Support doesn't work ...
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6.3) In the edit menu the trust values are not displayed correctly after
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signing uids. Why?
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6.4) What does "skipping pubkey 1: already loaded" mean?
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6.5) GnuPG 1.0.4 doesn't create ~/.gnupg ...
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6.6) An Elgamal signature does not verify anymore since version 1.0.2 ...
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6.7) Old versions of GnuPG can't verify Elgamal signatures
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6.8) When I use --clearsign, the plain text has sometimes extra dashes
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in it - why?
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6.9) What is the thing with "can't handle multiple signatures"?
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6.10) If I submit a key to a keyserver, nothing happens ...
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6.11) I get "gpg: waiting for lock ..."
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6.12) Older gpg binaries (e.g., 1.0) have problems with keys from newer
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gpg binaries ...
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6.13) With 1.0.4, I get "this cipher algorithm is deprecated ..."
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6.14) Some dates are displayed as ????-??-??. Why?
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6.15) I still have a problem. How do I report a bug?
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6.16) Why doesn't GnuPG support X.509 certificates?
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6.17) Why do national characters in my user ID look funny?
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6.18) I get 'sed' errors when running ./configure on Mac OS X ...
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6.19) Why does GnuPG 1.0.6 bail out on keyrings used with 1.0.7?
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6.20) I upgraded to GnuPG version 1.0.7 and now it takes longer to load my
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keyrings. What can I do?
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6.21) Doesn't a fully trusted user ID on a key prevent warning messages
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when encrypting to other IDs on the key?
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6.22) I just compiled GnuPG from source on my GNU/Linux RPM-based system
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and it's not working. Why?
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7. ADVANCED TOPICS
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7.1) How does this whole thing work?
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7.2) Why are some signatures with an ELG-E key valid?
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7.3) How does the whole trust thing work?
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7.4) What kind of output is this: "key C26EE891.298, uid 09FB: ...."?
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7.5) How do I interpret some of the informational outputs?
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7.6) Are the header lines of a cleartext signature part of the signed
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material?
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7.7) What is the list of preferred algorithms?
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7.8) How do I change the list of preferred algorithms?
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7.9) How can I import all the missing signer keys?
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8. ACKNOWLEDGEMENTS
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1. GENERAL
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1.1) What is GnuPG?
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GnuPG stands for GNU Privacy Guard and <http://www.gnupg.org>
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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 RFC 2440.
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<http://www.rfc-editor.org/>
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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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1.2) 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 5.1 for details.
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1.3) 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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1.4) 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 4.18 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 5.8 for details.
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2. SOURCES of INFORMATION
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2.1) Where can I find more information on GnuPG?
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On-line resources:
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The documentation page is located at <http://www.gnupg.org/documentation/>.
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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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At <http://www.gnupg.org/documentation/mailing-lists.html> 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.:
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gnupg-users: <http://marc.theaimsgroup.com/?l=gnupg-users&r=1&w=2>
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gnupg-devel: <http://marc.theaimsgroup.com/?l=gnupg-devel&r=1&w=2>
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PLEASE:
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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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The GnuPG source distribution contains a subdirectory:
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./doc
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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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2.2) 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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<ftp://ftp.gnupg.org/gcrypt/> or from one of the mirrors:
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<http://www.gnupg.org/download/mirrors.html>
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The current stable version is 1.2.2. 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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3. INSTALLATION
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3.1) 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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<http://www.gnupg.org/download/supported_systems.html>
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3.2) 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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--enable-static-rnd=linux
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In addition, there's also the kernel random device by Andi Maier
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<http://www.cosy.sbg.ac.at/~andi/SUNrand/>, 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 <http://www.gnupg.org/download/>
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to obtain EGD. Use:
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--enable-static-rnd=egd
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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 *very* 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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3.3) 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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<ftp://ftp.gnupg.dk/pub/contrib-dk/>. Look for:
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idea.c.gz (c module)
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idea.c.gz.sig (signature file)
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ideadll.zip (c module and win32 dll)
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ideadll.zip.sig (signature file)
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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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load-extension idea
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4. USAGE
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4.1) 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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$ gpg --fingerprint <user ID>
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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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4.2) 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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4.3) 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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4.4) 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 must pick exactly one command (with one exception,
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see below). You may 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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$ gpg [--option something] [--option2] [--option3 something] --command file
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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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$ gpg -r alice -o secret.txt -e test.txt
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If you write the options out in full, it is easier to read:
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$ gpg --recipient alice --output secret.txt --encrypt test.txt
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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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$ gpg --armor --recipient alice --output secret.txt --encrypt test.txt
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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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$ gpg [--armor] [--recipient alice] [--output secret.txt] --encrypt test.txt
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The optional parts can be rearranged any way you want:
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$ gpg --output secret.txt --recipient alice --armor --encrypt test.txt
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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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*The exception to using only one command:* 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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$ gpg [--options] --sign --encrypt foo.txt
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4.5) 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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4.6) 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 4.21.
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4.7) 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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4.8) 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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4.9) 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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4.10) 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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4.11) 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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4.12) How can I get list of key IDs used to encrypt a message?
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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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4.13) 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
481
only if 3DES or Twofish was used for symmetric-only encryption (this has
482
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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4.14) 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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If you want to do automatic signing, create a signing subkey
499
for your key (use the interactive key editing menu by issueing
500
the command 'gpg --edit-key keyID', enter "addkey" and select
501
the DSA key type).
502
Make sure that you use a passphrase (needed by the current
503
implementation).
504
gpg --export-secret-subkeys --no-comment foo >secring.auto
505
Copy secring.auto and the public keyring to a test directory.
506
Change to this directory.
507
gpg --homedir . --edit foo and use "passwd" to remove the
508
passphrase from the subkeys. You may also want to remove all
509
unused subkeys.
510
Copy secring.auto to a floppy and carry it to the target box.
511
512
On the target machine:
513
Install secring.auto as the secret keyring.
514
Now you can start your new service. It's also a good idea to
515
install an intrusion detection system so that you hopefully
516
get a notice of an successful intrusion, so that you in turn
517
can revoke all the subkeys installed on that machine and
518
install new subkeys.
519
520
4.15) Which email-client can I use with GnuPG?
521
522
Using GnuPG to encrypt email is one of the most popular uses.
523
Several mail clients or mail user agents (MUAs) support GnuPG to
524
varying degrees. Simplifying a bit, there are two ways mail can be
525
encrypted with GnuPG: the "old style" ASCII armor (i.e. cleartext
526
encryption), and RFC 2015 style (previously PGP/MIME, now OpenPGP).
527
The latter has full MIME support. Some MUAs support only one of
528
them, so whichever you actually use depends on your needs as well
529
as the capabilities of your addressee. As well, support may be
530
native to the MUA, or provided via "plug-ins" or external tools.
531
532
The following list is not exhaustive:
533
534
MUA OpenPGP ASCII How? (N,P,T)
535
-------------------------------------------------------------
536
Calypso N Y P (Unixmail)
537
Elm N Y T (mailpgp,morepgp)
538
Elm ME+ N Y N
539
Emacs/Gnus Y Y T (Mailcrypt,gpg.el)
540
Emacs/Mew Y Y N
541
Emacs/VM N Y T (Mailcrypt)
542
Evolution Y Y N
543
Exmh Y Y N
544
GNUMail.app Y Y P (PGPBundle)
545
GPGMail Y Y N
546
KMail (<=1.4.x) N Y N
547
KMail (1.5.x) Y(P) Y(N) P/N
548
Mozilla Y Y P (Enigmail)
549
Mulberry Y Y P
550
Mutt Y Y N
551
Sylpheed Y Y N
552
Claws-mail Y Y N
553
TkRat Y Y N
554
XEmacs/Gnus Y Y T (Mailcrypt)
555
XEmacs/Mew Y Y N
556
XEmacs/VM N Y T (Mailcrypt)
557
XFmail Y Y N
558
559
N - Native, P - Plug-in, T - External Tool
560
561
The following table lists proprietary MUAs. The GNU Project
562
suggests against the use of these programs, but they are listed
563
for interoperability reasons for your convenience.
564
565
MUA OpenPGP ASCII How? (N,P,T)
566
-------------------------------------------------------------
567
Apple Mail Y Y P (GPGMail)
568
Becky2 Y Y P (BkGnuPG)
569
Eudora Y Y P (EuroraGPG)
570
Eudora Pro Y Y P (EudoraGPG)
571
Lotus Notes N Y P
572
Netscape 4.x N Y P
573
Netscape 7.x Y Y P (Enigmail)
574
Novell Groupwise N Y P
575
Outlook N Y P (G-Data)
576
Outlook Express N Y P (GPGOE)
577
Pegasus N Y P (QDPGP,PM-PGP)
578
Pine N Y T (pgpenvelope,(gpg|pgp)4pine)
579
Postme N Y P (GPGPPL)
580
The Bat! N Y P (Ritlabs)
581
582
Good overviews of OpenPGP-support can be found at:
583
<http://www.openpgp.fr.st/courrier_en.html> and
584
<http://www.bretschneidernet.de/tips/secmua.html>.
585
586
Users of Win32 MUAs that lack OpenPGP support may look into
587
using GPGrelay <http://gpgrelay.sourceforge.net>, a small
588
email-relaying server that uses GnuPG to enable many email clients
589
to send and receive emails that conform to PGP-MIME (RFC 2015).
590
591
4.16) Can't we have a gpg library?
592
593
This has been frequently requested. However, the current viewpoint
594
of the GnuPG maintainers is that this would lead to several security
595
issues and will therefore not be implemented in the foreseeable
596
future. However, for some areas of application gpgme could do the
597
trick. You'll find it at <ftp://ftp.gnupg.org/gcrypt/alpha/gpgme>.
598
599
4.17) I have successfully generated a revocation certificate, but I don't
600
understand how to send it to the key servers.
601
602
Most keyservers don't accept a 'bare' revocation certificate. You
603
have to import the certificate into gpg first:
604
605
$ gpg --import my-revocation.asc
606
607
then send the revoked key to the keyservers:
608
609
$ gpg --keyserver certserver.pgp.com --send-keys mykeyid
610
611
(or use a keyserver web interface for this).
612
613
4.18) How do I put my keyring in a different directory?
614
615
GnuPG keeps several files in a special homedir directory. These
616
include the options file, pubring.gpg, secring.gpg, trustdb.gpg,
617
and others. GnuPG will always create and use these files. On unices,
618
the homedir is usually ~/.gnupg; on Windows it is name "gnupg" and
619
found below the user's application directory. Run the gpg and
620
pass the option --version to see the name of that directory.
621
622
If you want to put your keyrings somewhere else, use the option:
623
624
--homedir /my/path/
625
626
to make GnuPG create all its files in that directory. Your keyring
627
will be "/my/path/pubring.gpg". This way you can store your secrets
628
on a floppy disk. Don't use "--keyring" as its purpose is to specify
629
additional keyring files.
630
631
4.19) How do I verify signed packages?
632
633
Before you can verify the signature that accompanies a package,
634
you must first have the vendor, organisation, or issueing person's
635
key imported into your public keyring. To prevent GnuPG warning
636
messages the key should also be validated (or locally signed).
637
638
You will also need to download the detached signature file along
639
with the package. These files will usually have the same name as
640
the package, with either a binary (.sig) or ASCII armor (.asc)
641
extension.
642
643
Once their key has been imported, and the package and accompanying
644
signature files have been downloaded, use:
645
646
$ gpg --verify sigfile signed-file
647
648
If the signature file has the same base name as the package file,
649
the package can also be verified by specifying just the signature
650
file, as GnuPG will derive the package's file name from the name
651
given (less the .sig or .asc extension). For example, to verify a
652
package named foobar.tar.gz against its detached binary signature
653
file, use:
654
655
$ gpg --verify foobar.tar.gz.sig
656
657
4.20) How do I export a keyring with only selected signatures (keys)?
658
659
If you're wanting to create a keyring with only a subset of keys
660
selected from a master keyring (for a club, user group, or company
661
department for example), simply specify the keys you want to export:
662
663
$ gpg --armor --export key1 key2 key3 key4 > keys1-4.asc
664
665
4.21) I still have my secret key, but lost my public key. What can I do?
666
667
All OpenPGP secret keys have a copy of the public key inside them,
668
and in a worst-case scenario, you can create yourself a new public
669
key using the secret key.
670
671
A tool to convert a secret key into a public one has been included
672
(it's actually a new option for gpgsplit) and is available with GnuPG
673
versions 1.2.1 or later (or can be found in CVS). It works like this:
674
675
$ gpgsplit --no-split --secret-to-public secret.gpg >publickey.gpg
676
677
One should first try to export the secret key and convert just this
678
one. Using the entire secret keyring should work too. After this has
679
been done, the publickey.gpg file can be imported into GnuPG as usual.
680
681
4.22) Clearsigned messages sent from my web-mail account have an invalid
682
signature. Why?
683
684
Check to make sure the settings for your web-based email account
685
do not use HTML formatting for the pasted clearsigned message. This can
686
alter the message with embedded HTML markup tags or spaces, resulting
687
in an invalid signature. The recipient may be able to copy the signed
688
message block to a text file for verification, or the web email
689
service may allow you to attach the clearsigned message as a file
690
if plaintext messages are not an option.
691
692
693
5. COMPATIBILITY ISSUES
694
695
5.1) How can I encrypt a message with GnuPG so that PGP is able to decrypt it?
696
697
It depends on the PGP version.
698
699
PGP 2.x
700
You can't do that because PGP 2.x normally uses IDEA which is not
701
supported by GnuPG as it is patented (see 3.3), but if you have a
702
modified version of PGP you can try this:
703
704
$ gpg --rfc1991 --cipher-algo 3des ...
705
706
Please don't pipe the data to encrypt to gpg but provide it using a
707
filename; otherwise, PGP 2 will not be able to handle it.
708
709
As for conventional encryption, you can't do this for PGP 2.
710
711
PGP 5.x and higher
712
You need to provide two additional options:
713
714
--compress-algo 1 --cipher-algo cast5
715
716
You may also use "3des" instead of "cast5", and "blowfish" does not
717
work with all versions of PGP 5. You may also want to put:
718
719
compress-algo 1
720
721
into your ~/.gnupg/options file - this does not affect normal GnuPG
722
operation.
723
724
This applies to conventional encryption as well.
725
726
5.2) How do I migrate from PGP 2.x to GnuPG?
727
728
PGP 2 uses the RSA and IDEA encryption algorithms. Whereas the RSA
729
patent has expired and RSA is included as of GnuPG 1.0.3, the IDEA
730
algorithm is still patented until 2007. Under certain conditions you
731
may use IDEA even today. In that case, you may refer to Question
732
3.3 about how to add IDEA support to GnuPG and read
733
<http://www.gnupg.org/gph/en/pgp2x.html> to perform the migration.
734
735
5.3) (removed)
736
737
(empty)
738
739
5.4) Why is PGP 5.x not able to encrypt messages with some keys?
740
741
PGP, Inc. refuses to accept Elgamal keys of type 20 even for
742
encryption. They only support type 16 (which is identical at least
743
for decryption). To be more inter-operable, GnuPG (starting with
744
version 0.3.3) now also uses type 16 for the Elgamal subkey which is
745
created if the default key algorithm is chosen. You may add a type
746
16 Elgamal key to your public key, which is easy as your key
747
signatures are still valid.
748
749
5.5) Why is PGP 5.x not able to verify my messages?
750
751
PGP 5.x does not accept v4 signatures for data material but OpenPGP
752
requests generation of v4 signatures for all kind of data, that's why
753
GnuPG defaults to them. Use the option "--force-v3-sigs" to generate
754
v3 signatures for data.
755
756
5.6) How do I transfer owner trust values from PGP to GnuPG?
757
758
There is a script in the tools directory to help you. After you have
759
imported the PGP keyring you can give this command:
760
761
$ lspgpot pgpkeyring | gpg --import-ownertrust
762
763
where pgpkeyring is the original keyring and not the GnuPG keyring
764
you might have created in the first step.
765
766
5.7) PGP does not like my secret key.
767
768
Older PGPs probably bail out on some private comment packets used by
769
GnuPG. These packets are fully in compliance with OpenPGP; however
770
PGP is not really OpenPGP aware. A workaround is to export the
771
secret keys with this command:
772
773
$ gpg --export-secret-keys --no-comment -a your-KeyID
774
775
Another possibility is this: by default, GnuPG encrypts your secret
776
key using the Blowfish symmetric algorithm. Older PGPs will only
777
understand 3DES, CAST5, or IDEA symmetric algorithms. Using the
778
following method you can re-encrypt your secret gpg key with a
779
different algo:
780
781
$ gpg --s2k-cipher-algo=CAST5 --s2k-digest-algo=SHA1
782
--compress-algo=1 --edit-key <username>
783
784
Then use passwd to change the password (just change it to the same
785
thing, but it will encrypt the key with CAST5 this time).
786
787
Now you can export it and PGP should be able to handle it.
788
789
For PGP 6.x the following options work to export a key:
790
791
$ gpg --s2k-cipher-algo 3des --compress-algo 1 --rfc1991
792
--export-secret-keys <KeyID>
793
794
5.8) GnuPG no longer installs a ~/.gnupg/options file. Is it missing?
795
796
No. The ~/.gnupg/options file has been renamed to ~/.gnupg/gpg.conf for
797
new installs as of version 1.1.92. If an existing ~/.gnupg/options file
798
is found during an upgrade it will still be used, but this change was
799
required to have a more consistent naming scheme with forthcoming tools.
800
An existing options file can be renamed to gpg.conf for users upgrading,
801
or receiving the message that the "old default options file" is ignored
802
(occurs if both a gpg.conf and an options file are found).
803
804
5.9) How do you export GnuPG keys for use with PGP?
805
806
This has come up fairly often, so here's the HOWTO:
807
808
PGP can (for most key types) use secret keys generated by GnuPG. The
809
problems that come up occasionally are generally because GnuPG
810
supports a few more features from the OpenPGP standard than PGP does.
811
If your secret key has any of those features in use, then PGP will
812
reject the key or you will have problems communicating later. Note
813
that PGP doesn't do Elgamal signing keys at all, so they are not
814
usable with any version.
815
816
These instructions should work for GnuPG 1.0.7 and later, and PGP
817
7.0.3 and later.
818
819
Start by editing the key. Most of this line is not really necessary
820
as the default values are correct, but it does not hurt to repeat the
821
values, as this will override them in case you have something else set
822
in your options file.
823
824
$ gpg --s2k-cipher-algo cast5 --s2k-digest-algo sha1 --s2k-mode 3
825
--simple-sk-checksum --edit KeyID
826
827
Turn off some features. Set the list of preferred ciphers, hashes,
828
and compression algorithms to things that PGP can handle. (Yes, I
829
know this is an odd list of ciphers, but this is what PGP itself uses,
830
minus IDEA).
831
832
> setpref S9 S8 S7 S3 S2 S10 H2 H3 Z1 Z0
833
834
Now put the list of preferences onto the key.
835
836
> updpref
837
838
Finally we must decrypt and re-encrypt the key, making sure that we
839
encrypt with a cipher that PGP likes. We set this up in the --edit
840
line above, so now we just need to change the passphrase to make it
841
take effect. You can use the same passphrase if you like, or take
842
this opportunity to actually change it.
843
844
> passwd
845
846
Save our work.
847
848
> save
849
850
Now we can do the usual export:
851
852
$ gpg --export KeyID > mypublickey.pgp
853
$ gpg --export-secret-key KeyID > mysecretkey.pgp
854
855
Thanks to David Shaw for this information!
856
857
858
6. PROBLEMS and ERROR MESSAGES
859
860
6.1) Why do I get "gpg: Warning: using insecure memory!"
861
862
On many systems this program should be installed as setuid(root).
863
This is necessary to lock memory pages. Locking memory pages prevents
864
the operating system from writing them to disk and thereby keeping your
865
secret keys really secret. If you get no warning message about insecure
866
memory your operating system supports locking without being root. The
867
program drops root privileges as soon as locked memory is allocated.
868
869
To setuid(root) permissions on the gpg binary you can either use:
870
871
$ chmod u+s /path/to/gpg
872
873
or
874
875
$ chmod 4755 /path/to/gpg
876
877
Some refrain from using setuid(root) unless absolutely required for
878
security reasons. Please check with your system administrator if you
879
are not able to make these determinations yourself.
880
881
On UnixWare 2.x and 7.x you should install GnuPG with the 'plock'
882
privilege to get the same effect:
883
884
$ filepriv -f plock /path/to/gpg
885
886
If you can't or don't want to install GnuPG setuid(root), you can
887
use the option "--no-secmem-warning" or put:
888
889
no-secmem-warning
890
891
in your ~/.gnupg/options or ~/.gnupg/gpg.conf file (this disables
892
the warning).
893
894
On some systems (e.g., Windows) GnuPG does not lock memory pages
895
and older GnuPG versions (<=1.0.4) issue the warning:
896
897
gpg: Please note that you don't have secure memory
898
899
This warning can't be switched off by the above option because it
900
was thought to be too serious an issue. However, it confused users
901
too much, so the warning was eventually removed.
902
903
6.2) Large File Support doesn't work ...
904
905
LFS works correctly in post-1.0.4 versions. If configure doesn't
906
detect it, try a different (i.e., better) compiler. egcs 1.1.2 works
907
fine, other gccs sometimes don't. BTW, several compilation problems
908
of GnuPG 1.0.3 and 1.0.4 on HP-UX and Solaris were due to broken LFS
909
support.
910
911
6.3) In the edit menu the trust values are not displayed correctly after
912
signing uids. Why?
913
914
This happens because some information is stored immediately in
915
the trustdb, but the actual trust calculation can be done after the
916
save command. This is a "not easy to fix" design bug which will be
917
addressed in some future release.
918
919
6.4) What does "skipping pubkey 1: already loaded" mean?
920
921
As of GnuPG 1.0.3, the RSA algorithm is included. If you still have
922
a "load-extension rsa" in your options file, the above message
923
occurs. Just remove the load command from the options file.
924
925
6.5) GnuPG 1.0.4 doesn't create ~/.gnupg ...
926
927
That's a known bug, already fixed in newer versions.
928
929
6.6) An Elgamal signature does not verify anymore since version 1.0.2 ...
930
931
Use the option --emulate-md-encode-bug.
932
933
6.7) Old versions of GnuPG can't verify Elgamal signatures
934
935
Update to GnuPG 1.0.2 or newer.
936
937
6.8) When I use --clearsign, the plain text has sometimes extra dashes
938
in it - why?
939
940
This is called dash-escaped text and is required by OpenPGP.
941
It always happens when a line starts with a dash ("-") and is
942
needed to make the lines that structure signature and text
943
(i.e., "-----BEGIN PGP SIGNATURE-----") to be the only lines
944
that start with two dashes.
945
946
If you use GnuPG to process those messages, the extra dashes
947
are removed. Good mail clients remove those extra dashes when
948
displaying such a message.
949
950
6.9) What is the thing with "can't handle multiple signatures"?
951
952
Due to different message formats GnuPG is not always able to split
953
a file with multiple signatures unambiguously into its parts. This
954
error message informs you that there is something wrong with the input.
955
956
The only way to have multiple signatures in a file is by using the
957
OpenPGP format with one-pass-signature packets (which is GnuPG's
958
default) or the cleartext signed format.
959
960
6.10) If I submit a key to a keyserver, nothing happens ...
961
962
You are most likely using GnuPG 1.0.2 or older on Windows. That's
963
feature isn't yet implemented, but it's a bug not to say it. Newer
964
versions issue a warning. Upgrade to 1.4.5 or newer.
965
966
6.11) I get "gpg: waiting for lock ..."
967
968
A previous instance of gpg has most likely exited abnormally and left
969
a lock file. Go to ~/.gnupg and look for .*.lock files and remove them.
970
971
6.12) Older gpg binaries (e.g., 1.0) have problems with keys from newer
972
gpg binaries ...
973
974
As of 1.0.3, keys generated with gpg are created with preferences to
975
TWOFISH (and AES since 1.0.4) and that also means that they have the
976
capability to use the new MDC encryption method. This will go into
977
OpenPGP soon, and is also suppoted by PGP 7. This new method avoids
978
a (not so new) attack on all email encryption systems.
979
980
This in turn means that pre-1.0.3 gpg binaries have problems with
981
newer keys. Because of security and bug fixes, you should keep your
982
GnuPG installation in a recent state anyway. As a workaround, you can
983
force gpg to use a previous default cipher algo by putting:
984
985
cipher-algo cast5
986
987
into your options file.
988
989
6.13) With 1.0.4, I get "this cipher algorithm is deprecated ..."
990
991
If you just generated a new key and get this message while
992
encrypting, you've witnessed a bug in 1.0.4. It uses the new AES
993
cipher Rijndael that is incorrectly being referred as "deprecated".
994
Ignore this warning, more recent versions of gpg are corrected.
995
996
6.14) Some dates are displayed as ????-??-??. Why?
997
998
Due to constraints in most libc implementations, dates beyond
999
2038-01-19 can't be displayed correctly. 64-bit OSes are not
1000
affected by this problem. To avoid printing wrong dates, GnuPG
1001
instead prints some question marks. To see the correct value, you
1002
can use the options --with-colons and --fixed-list-mode.
1003
1004
6.15) I still have a problem. How do I report a bug?
1005
1006
Are you sure that it's not been mentioned somewhere on the mailing
1007
lists? Did you have a look at the bug list (you'll find a link to
1008
the list of reported bugs on the documentation page). If you're not
1009
sure about it being a bug, you can send mail to the gnupg-devel
1010
list. Otherwise, use the bug tracking system
1011
<http://bugs.gnupg.org>.
1012
1013
6.16) Why doesn't GnuPG support X.509 certificates?
1014
1015
GnuPG, first and foremost, is an implementation of the OpenPGP
1016
standard (RFC 2440), which is a competing infrastructure, different
1017
from X.509.
1018
1019
They are both public-key cryptosystems, but how the public keys are
1020
actually handled is different.
1021
1022
6.17) Why do national characters in my user ID look funny?
1023
1024
According to OpenPGP, GnuPG encodes user ID strings (and other
1025
things) using UTF-8. In this encoding of Unicode, most national
1026
characters get encoded as two- or three-byte sequences. For
1027
example, å (0xE5 in ISO-8859-1) becomes Ã¥ (0xC3,
1028
0xA5). This might also be the reason why keyservers can't find
1029
your key.
1030
1031
6.18) I get 'sed' errors when running ./configure on Mac OS X ...
1032
1033
This will be fixed after GnuPG has been upgraded to autoconf-2.50.
1034
Until then, find the line setting CDPATH in the configure script
1035
and place an:
1036
1037
unset CDPATH
1038
1039
statement below it.
1040
1041
6.19) Why does GnuPG 1.0.6 bail out on keyrings used with 1.0.7?
1042
1043
There is a small bug in 1.0.6 which didn't parse trust packets
1044
correctly. You may want to apply this patch if you can't upgrade:
1045
1046
<http://www.gnupg.org/developer/gpg-woody-fix.txt>
1047
1048
6.20) I upgraded to GnuPG version 1.0.7 and now it takes longer to load my
1049
keyrings. What can I do?
1050
1051
The way signature states are stored has changed so that v3 signatures
1052
can be supported. You can use the new --rebuild-keydb-caches migration
1053
command, which was built into this release and increases the speed of
1054
many operations for existing keyrings.
1055
1056
6.21) Doesn't a fully trusted user ID on a key prevent warning messages
1057
when encrypting to other IDs on the key?
1058
1059
No. That was actually a key validity bug in GnuPG 1.2.1 and earlier
1060
versions. As part of the development of GnuPG 1.2.2, a bug was
1061
discovered in the key validation code. This bug causes keys with
1062
more than one user ID to give all user IDs on the key the amount of
1063
validity given to the most-valid key. The bug has been fixed in GnuPG
1064
release 1.2.2, and upgrading is the recommended fix for this problem.
1065
More information and a patch for a some pre-1.2.2 versions of GnuPG
1066
can be found at:
1067
1068
<http://lists.gnupg.org/pipermail/gnupg-announce/2003q2/000268.html>
1069
1070
6.22) I just compiled GnuPG from source on my GNU/Linux RPM-based system
1071
and it's not working. Why?
1072
1073
Many GNU/Linux distributions that are RPM-based will install a
1074
version of GnuPG as part of its standard installation, placing the
1075
binaries in the /usr/bin directory. Later, compiling and installing
1076
GnuPG from source other than from a source RPM won't normally
1077
overwrite these files, as the default location for placement of
1078
GnuPG binaries is in /usr/local/bin unless the '--prefix' switch
1079
is used during compile to specify an alternate location. Since the
1080
/usr/bin directory more than likely appears in your path before
1081
/usr/local/bin, the older RPM-version binaries will continue to
1082
be used when called since they were not replaced.
1083
1084
To resolve this, uninstall the RPM-based version with 'rpm -e gnupg'
1085
before installing the binaries compiled from source. If dependency
1086
errors are displayed when attempting to uninstall the RPM (such as
1087
when Red Hat's up2date is also installed, which uses GnuPG), uninstall
1088
the RPM with 'rpm -e gnupg --nodeps' to force the uninstall. Any
1089
dependent files should be automatically replaced during the install
1090
of the compiled version. If the default /usr/local/bin directory is
1091
used, some packages such as SuSE's Yast Online Update may need to be
1092
configured to look for GnuPG binaries in the /usr/local/bin directory,
1093
or symlinks can be created in /usr/bin that point to the binaries
1094
located in /usr/local/bin.
1095
1096
1097
7. ADVANCED TOPICS
1098
1099
7.1) How does this whole thing work?
1100
1101
To generate a secret/public keypair, run:
1102
1103
$ gpg --gen-key
1104
1105
and choose the default values.
1106
1107
Data that is encrypted with a public key can only be decrypted by
1108
the matching secret key. The secret key is protected by a password,
1109
the public key is not.
1110
1111
So to send your friend a message, you would encrypt your message
1112
with his public key, and he would only be able to decrypt it by
1113
having the secret key and putting in the password to use his secret
1114
key.
1115
1116
GnuPG is also useful for signing things. Files that are encrypted
1117
with the secret key can be decrypted with the public key. To sign
1118
something, a hash is taken of the data, and then the hash is in some
1119
form encoded with the secret key. If someone has your public key, they
1120
can verify that it is from you and that it hasn't changed by checking
1121
the encoded form of the hash with the public key.
1122
1123
A keyring is just a large file that stores keys. You have a public
1124
keyring where you store yours and your friend's public keys. You have
1125
a secret keyring that you keep your secret key on, and should be very
1126
careful with. Never ever give anyone else access to it and use a *good*
1127
passphrase to protect the data in it.
1128
1129
You can 'conventionally' encrypt something by using the option 'gpg -c'.
1130
It is encrypted using a passphrase, and does not use public and secret
1131
keys. If the person you send the data to knows that passphrase, they
1132
can decrypt it. This is usually most useful for encrypting things to
1133
yourself, although you can encrypt things to your own public key in the
1134
same way. It should be used for communication with partners you know
1135
and where it is easy to exchange the passphrases (e.g. with your boy
1136
friend or your wife). The advantage is that you can change the
1137
passphrase from time to time and decrease the risk, that many old
1138
messages may be decrypted by people who accidently got your passphrase.
1139
1140
You can add and copy keys to and from your keyring with the 'gpg
1141
--import' and 'gpg --export' command. 'gpg --export-secret-keys' will
1142
export secret keys. This is normally not useful, but you can generate
1143
the key on one machine then move it to another machine.
1144
1145
Keys can be signed under the 'gpg --edit-key' option. When you sign a
1146
key, you are saying that you are certain that the key belongs to the
1147
person it says it comes from. You should be very sure that is really
1148
that person: You should verify the key fingerprint with:
1149
1150
$ gpg --fingerprint KeyID
1151
1152
over the phone (if you really know the voice of the other person), at
1153
a key signing party (which are often held at computer conferences),
1154
or at a meeting of your local GNU/Linux User Group.
1155
1156
Hmm, what else. You may use the option '-o filename' to force output
1157
to this filename (use '-' to force output to stdout). '-r' just lets
1158
you specify the recipient (which public key you encrypt with) on the
1159
command line instead of typing it interactively.
1160
1161
Oh yeah, this is important. By default all data is encrypted in some
1162
weird binary format. If you want to have things appear in ASCII text
1163
that is readable, just add the '-a' option. But the preferred method
1164
is to use a MIME aware mail reader (Mutt, Pine and many more).
1165
1166
There is a small security glitch in the OpenPGP (and therefore GnuPG)
1167
system; to avoid this you should always sign and encrypt a message
1168
instead of only encrypting it.
1169
1170
7.2) Why are some signatures with an ELG-E key valid?
1171
1172
These are Elgamal keys generated by GnuPG in v3 (RFC 1991) packets.
1173
The OpenPGP draft later changed the algorithm identifier for Elgamal
1174
keys which are usable for signatures and encryption from 16 to 20.
1175
GnuPG now uses 20 when it generates new Elgamal keys but still
1176
accepts 16 (which is according to OpenPGP "encryption only") if this
1177
key is in a v3 packet. GnuPG is the only program which had used
1178
these v3 Elgamal keys - so this assumption is quite safe.
1179
1180
7.3) How does the whole trust thing work?
1181
1182
It works more or less like PGP. The difference is that the trust is
1183
computed at the time it is needed. This is one of the reasons for
1184
the trustdb which holds a list of valid key signatures. If you are
1185
not running in batch mode you will be asked to assign a trust
1186
parameter (ownertrust) to a key.
1187
1188
You can see the validity (calculated trust value) using this
1189
command.
1190
1191
$ gpg --list-keys --with-colons
1192
1193
If the first field is "pub" or "uid", the second field shows you the
1194
trust:
1195
1196
o = Unknown (this key is new to the system)
1197
e = The key has expired
1198
q = Undefined (no value assigned)
1199
n = Don't trust this key at all
1200
m = There is marginal trust in this key
1201
f = The key is full trusted
1202
u = The key is ultimately trusted; this is only used
1203
for keys for which the secret key is also available.
1204
r = The key has been revoked
1205
d = The key has been disabled
1206
1207
The value in the "pub" record is the best one of all "uid" records.
1208
You can get a list of the assigned trust values (how much you trust
1209
the owner to correctly sign another person's key) with:
1210
1211
$ gpg --list-ownertrust
1212
1213
The first field is the fingerprint of the primary key, the second
1214
field is the assigned value:
1215
1216
- = No ownertrust value yet assigned or calculated.
1217
n = Never trust this keyholder to correctly verify others signatures.
1218
m = Have marginal trust in the keyholders capability to sign other
1219
keys.
1220
f = Assume that the key holder really knows how to sign keys.
1221
u = No need to trust ourself because we have the secret key.
1222
1223
Keep these values confidential because they express your opinions
1224
about others. PGP stores this information with the keyring thus it
1225
is not a good idea to publish a PGP keyring instead of exporting the
1226
keyring. GnuPG stores the trust in the trustdb.gpg file so it is okay
1227
to give a gpg keyring away (but we have a --export command too).
1228
1229
7.4) What kind of output is this: "key C26EE891.298, uid 09FB: ...."?
1230
1231
This is the internal representation of a user ID in the trustdb.
1232
"C26EE891" is the keyid, "298" is the local ID (a record number in
1233
the trustdb) and "09FB" is the last two bytes of a ripe-md-160 hash
1234
of the user ID for this key.
1235
1236
7.5) How do I interpret some of the informational outputs?
1237
1238
While checking the validity of a key, GnuPG sometimes prints some
1239
information which is prefixed with information about the checked
1240
item.
1241
1242
"key 12345678.3456"
1243
1244
This is about the key with key ID 12345678 and the internal number
1245
3456, which is the record number of the so called directory record
1246
in the trustdb.
1247
1248
"uid 12345678.3456/ACDE"
1249
1250
This is about the user ID for the same key. To identify the user ID
1251
the last two bytes of a ripe-md-160 over the user ID ring is printed.
1252
1253
"sig 12345678.3456/ACDE/9A8B7C6D"
1254
1255
This is about the signature with key ID 9A8B7C6D for the above key
1256
and user ID, if it is a signature which is direct on a key, the user
1257
ID part is empty (..//..).
1258
1259
7.6) Are the header lines of a cleartext signature part of the signed
1260
material?
1261
1262
No. For example you can add or remove "Comment:" lines. They have
1263
a purpose like the mail header lines. However a "Hash:" line is
1264
needed for OpenPGP signatures to tell the parser which hash
1265
algorithm to use.
1266
1267
7.7) What is the list of preferred algorithms?
1268
1269
The list of preferred algorithms is a list of cipher, hash and
1270
compression algorithms stored in the self-signature of a key during
1271
key generation. When you encrypt a document, GnuPG uses this list
1272
(which is then part of a public key) to determine which algorithms
1273
to use. Basically it tells other people what algorithms the
1274
recipient is able to handle and provides an order of preference.
1275
1276
7.8) How do I change the list of preferred algorithms?
1277
1278
In version 1.0.7 or later, you can use the edit menu and set the
1279
new list of preference using the command "setpref"; the format of
1280
this command resembles the output of the command "pref". The
1281
preference is not changed immediately but the set preference will
1282
be used when a new user ID is created. If you want to update the
1283
preferences for existing user IDs, select those user IDs (or select
1284
none to update all) and enter the command "updpref". Note that the
1285
timestamp of the self-signature is increased by one second when
1286
running this command.
1287
1288
7.9) How can I import all the missing signer keys?
1289
1290
If you imported a key and you want to also import all the signer's
1291
keys, you can do this with this command:
1292
1293
gpg --check-sigs --with-colon KEYID \
1294
| awk -F: '$1 == "sig" && $2 == "?" { print $5 }' \
1295
| sort | uniq | xargs echo gpg --recv-keys
1296
1297
Note that the invocation of sort is also required to wait for the
1298
of the listing before before starting the import.
1299
1300
1301
8. ACKNOWLEDGEMENTS
1302
1303
Many thanks to Nils Ellmenreich for maintaining this FAQ file for
1304
such a long time, Werner Koch for the original FAQ file, and to all
1305
posters to gnupg-users and gnupg-devel. They all provided most of
1306
the answers.
1307
1308
Also thanks to Casper Dik for providing us with a script to generate
1309
this FAQ (he uses it for the excellent Solaris2 FAQ).
1310
1311
1312
Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.,
1313
51 Franklin Street, Fifth Floor, Boston, MA 02111, USA
1314
1315
Verbatim copying and distribution of this entire article is permitted in
1316
any medium, provided this notice is preserved.
3
A FAQ is a fast moving target and thus we don't distribute it anymore
4
with GnuPG. You may retrieve the current FAQ in HTML format at
5
6
http://www.gnupg.org/faq/GnuPG-FAQ.html
7
8
or in plain text format at the FTP server:
9
10
ftp://ftp.gnupg.org/gcrypt/gnupg/GnuPG-FAQ.txt
11
12
13
Loggerhead is a web-based interface for Breezy
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