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-
- GnuPG Frequently Asked Questions
-
-
- Version: 1.6.3
- Last-Modified: Jul 30, 2003
- Maintained-by: David D. Scribner, <faq 'at' gnupg.org>
-
-
- This is the GnuPG FAQ. The latest HTML version is available
- here. <http://www.gnupg.org/documentation/faqs.html>
-
- The index is generated automatically, so there may be errors. Not all
- questions may be in the section they belong to. Suggestions about how
- to improve the structure of this FAQ are welcome.
-
- Please send additions and corrections to the maintainer. It would be
- most convenient if you could provide the answer to be included here
- as well. Your help is very much appreciated!
-
- Please, don't send message like "This should be a FAQ - what's the
- answer?". If it hasn't been asked before, it isn't a FAQ. In that case
- you could search in the mailing list archive.
-
-
- 1. GENERAL
- 1.1) What is GnuPG?
- 1.2) Is GnuPG compatible with PGP?
- 1.3) Is GnuPG free to use for personal or commercial use?
- 1.4) What conventions are used in this FAQ?
-
- 2. SOURCES of INFORMATION
- 2.1) Where can I find more information on GnuPG?
- 2.2) Where do I get GnuPG?
-
- 3. INSTALLATION
- 3.1) Which OSes does GnuPG run on?
- 3.2) Which random data gatherer should I use?
- 3.3) How do I include support for RSA and IDEA?
-
- 4. USAGE
- 4.1) What is the recommended key size?
- 4.2) Why does it sometimes take so long to create keys?
- 4.3) And it really takes long when I work on a remote system. Why?
- 4.4) What is the difference between options and commands?
- 4.5) I can't delete a user ID on my secret keyring because it has
- already been deleted on my public keyring. What can I do?
- 4.6) I can't delete my secret key because the public key disappeared.
- What can I do?
- 4.7) What are trust, validity and ownertrust?
- 4.8) How do I sign a patch file?
- 4.9) Where is the "encrypt-to-self" option?
- 4.10) How can I get rid of the Version and Comment headers in armored
- messages?
- 4.11) What does the "You are using the xxxx character set." mean?
- 4.12) How can I get list of key IDs used to encrypt a message?
- 4.13) Why can't I decrypt files encrypted as symmetrical-only (-c) with
- a version of GnuPG prior to 1.0.1.
- 4.14) How can I use GnuPG in an automated environment?
- 4.15) Which email-client can I use with GnuPG?
- 4.16) Can't we have a gpg library?
- 4.17) I have successfully generated a revocation certificate, but I don't
- understand how to send it to the key servers.
- 4.18) How do I put my keyring in a different directory?
- 4.19) How do I verify signed packages?
- 4.20) How do I export a keyring with only selected signatures (keys)?
- 4.21) I still have my secret key, but lost my public key. What can I do?
- 4.22) Clearsigned messages sent from my web-mail account have an invalid
- signature. Why?
-
- 5. COMPATIBILITY ISSUES
- 5.1) How can I encrypt a message with GnuPG so that PGP is able to decrypt it?
- 5.2) How do I migrate from PGP 2.x to GnuPG?
- 5.3) (removed)
- 5.4) Why is PGP 5.x not able to encrypt messages with some keys?
- 5.5) Why is PGP 5.x not able to verify my messages?
- 5.6) How do I transfer owner trust values from PGP to GnuPG?
- 5.7) PGP does not like my secret key.
- 5.8) GnuPG no longer installs a ~/.gnupg/options file. Is it missing?
- 5.9) How do you export GnuPG keys for use with PGP?
-
- 6. PROBLEMS and ERROR MESSAGES
- 6.1) Why do I get "gpg: Warning: using insecure memory!"
- 6.2) Large File Support doesn't work ...
- 6.3) In the edit menu the trust values are not displayed correctly after
- signing uids. Why?
- 6.4) What does "skipping pubkey 1: already loaded" mean?
- 6.5) GnuPG 1.0.4 doesn't create ~/.gnupg ...
- 6.6) An ElGamal signature does not verify anymore since version 1.0.2 ...
- 6.7) Old versions of GnuPG can't verify ElGamal signatures
- 6.8) When I use --clearsign, the plain text has sometimes extra dashes
- in it - why?
- 6.9) What is the thing with "can't handle multiple signatures"?
- 6.10) If I submit a key to a keyserver, nothing happens ...
- 6.11) I get "gpg: waiting for lock ..."
- 6.12) Older gpg binaries (e.g., 1.0) have problems with keys from newer
- gpg binaries ...
- 6.13) With 1.0.4, I get "this cipher algorithm is deprecated ..."
- 6.14) Some dates are displayed as ????-??-??. Why?
- 6.15) I still have a problem. How do I report a bug?
- 6.16) Why doesn't GnuPG support X.509 certificates?
- 6.17) Why do national characters in my user ID look funny?
- 6.18) I get 'sed' errors when running ./configure on Mac OS X ...
- 6.19) Why does GnuPG 1.0.6 bail out on keyrings used with 1.0.7?
- 6.20) I upgraded to GnuPG version 1.0.7 and now it takes longer to load my
- keyrings. What can I do?
- 6.21) Doesn't a fully trusted user ID on a key prevent warning messages
- when encrypting to other IDs on the key?
- 6.22) I just compiled GnuPG from source on my GNU/Linux RPM-based system
- and it's not working. Why?
-
- 7. ADVANCED TOPICS
- 7.1) How does this whole thing work?
- 7.2) Why are some signatures with an ELG-E key valid?
- 7.3) How does the whole trust thing work?
- 7.4) What kind of output is this: "key C26EE891.298, uid 09FB: ...."?
- 7.5) How do I interpret some of the informational outputs?
- 7.6) Are the header lines of a cleartext signature part of the signed
- material?
- 7.7) What is the list of preferred algorithms?
- 7.8) How do I change the list of preferred algorithms?
-
- 8. ACKNOWLEDGEMENTS
-
-
- 1. GENERAL
-
- 1.1) What is GnuPG?
-
- GnuPG stands for GNU Privacy Guard and <http://www.gnupg.org>
- is GNU's tool for secure communication and data storage. It can be
- used to encrypt data and to create digital signatures. It includes
- an advanced key management facility and is compliant with the
- proposed OpenPGP Internet standard as described in RFC 2440.
- <http://www.rfc-editor.org/>
- As such, it is aimed to be compatible with PGP from NAI, Inc.
-
- 1.2) Is GnuPG compatible with PGP?
-
- In general, yes. GnuPG and newer PGP releases should be implementing
- the OpenPGP standard. But there are some interoperability problems.
- See question 5.1 for details.
-
- 1.3) Is GnuPG free to use for personal or commercial use?
-
- Yes. GnuPG is part of the GNU family of tools and applications built
- and provided in accordance with the Free Software Foundation (FSF)
- General Public License (GPL). Therefore the software is free to copy,
- use, modify and distribute in accordance with that license. Please
- read the file titled COPYING that accompanies the application for
- more information.
-
- 1.4) What conventions are used in this FAQ?
-
- Although GnuPG is being developed for several operating systems
- (often in parallel), the conventions used in this FAQ reflect a
- UNIX shell environment. For Win32 users, references to a shell
- prompt (`$') should be interpreted as a command prompt (`>'),
- directory names separated by a forward slash (`/') may need to be
- converted to a back slash (`\'), and a tilde (`~') represents a
- user's "home" directory (reference question 4.18 for an example).
-
- Some command-lines presented in this FAQ are too long to properly
- display in some browsers for the web page version of this file, and
- have been split into two or more lines. For these commands please
- remember to enter the entire command-string on one line or the
- command will error, or at minimum not give the desired results.
-
- Please keep in mind that this FAQ contains information that may not
- apply to your particular version, as new features and bug fixes are
- added on a continuing basis (reference the NEWS file included with
- the source or package for noteworthy changes between versions). One
- item to note is that starting with GnuPG version 1.1.92 the file
- containing user options and settings has been renamed from "options"
- to "gpg.conf". Information in the FAQ that relates to the options
- file may be interchangable with the newer gpg.conf file in many
- instances. See question 5.8 for details.
-
-
- 2. SOURCES of INFORMATION
-
- 2.1) Where can I find more information on GnuPG?
-
- On-line resources:
-
- The documentation page is located at <http://www.gnupg.org/documentation/>.
- Also, have a look at the HOWTOs and the GNU Privacy Handbook (GPH,
- available in English, Spanish and Russian). The latter provides a
- detailed user's guide to GnuPG. You'll also find a document about how
- to convert from PGP 2.x to GnuPG.
-
- At <http://www.gnupg.org/documentation/mailing-lists.html> you'll find
- an online archive of the GnuPG mailing lists. Most interesting should
- be gnupg-users for all user-related issues and gnupg-devel if you want
- to get in touch with the developers.
-
- In addition, searchable archives can be found on MARC, e.g.:
- gnupg-users: <http://marc.theaimsgroup.com/?l=gnupg-users&r=1&w=2>
- gnupg-devel: <http://marc.theaimsgroup.com/?l=gnupg-devel&r=1&w=2>
-
- PLEASE:
- Before posting to a list, read this FAQ and the available documentation.
- In addition, search the list archive - maybe your question has already
- been discussed. This way you help people focus on topics that have not
- yet been resolved.
-
- The GnuPG source distribution contains a subdirectory:
-
- ./doc
-
- where some additional documentation is located (mainly interesting
- for hackers, not the casual user).
-
- 2.2) Where do I get GnuPG?
-
- You can download the GNU Privacy Guard from its primary FTP server
- <ftp://ftp.gnupg.org/gcrypt/> or from one of the mirrors:
-
- <http://www.gnupg.org/download/mirrors.html>
-
- The current stable version is 1.2.2. Please upgrade to this version as
- it includes additional features, functions and security fixes that may
- not have existed in prior versions.
-
-
- 3. INSTALLATION
-
- 3.1) Which OSes does GnuPG run on?
-
- It should run on most Unices as well as Windows versions (including
- Windows NT/2000) and Macintosh OS/X. A list of OSes reported to be OK
- is presented at:
-
- <http://www.gnupg.org/download/supported_systems.html>
-
- 3.2) Which random data gatherer should I use?
-
- "Good" random numbers are crucial for the security of your encryption.
- Different operating systems provide a variety of more or less quality
- random data. Linux and *BSD provide kernel generated random data
- through /dev/random - this should be the preferred choice on these
- systems. Also Solaris users with the SUNWski package installed have
- a /dev/random. In these cases, use the configure option:
-
- --enable-static-rnd=linux
-
- In addition, there's also the kernel random device by Andi Maier
- <http://www.cosy.sbg.ac.at/~andi/SUNrand/>, but it's still beta. Use at your
- own risk!
-
- On other systems, the Entropy Gathering Daemon (EGD) is a good choice.
- It is a perl-daemon that monitors system activity and hashes it into
- random data. See the download page <http://www.gnupg.org/download/>
- to obtain EGD. Use:
-
- --enable-static-rnd=egd
-
- here.
-
- If the above options do not work, you can use the random number
- generator "unix". This is *very* slow and should be avoided. The
- random quality isn't very good so don't use it on sensitive data.
-
- 3.3) How do I include support for RSA and IDEA?
-
- RSA is included as of GnuPG version 1.0.3.
-
- The official GnuPG distribution does not contain IDEA due to a patent
- restriction. The patent does not expire before 2007 so don't expect
- official support before then.
-
- However, there is an unofficial module to include it even in earlier
- versions of GnuPG. It's available from
- <ftp://ftp.gnupg.dk/pub/contrib-dk/>. Look for:
-
- idea.c.gz (c module)
- idea.c.gz.sig (signature file)
-
- ideadll.zip (c module and win32 dll)
- ideadll.zip.sig (signature file)
-
- Compilation directives are in the headers of these files. You will
- then need to add the following line to your ~/.gnupg/gpg.conf or
- ~/.gnupg/options file:
-
- load-extension idea
-
-
- 4. USAGE
-
- 4.1) What is the recommended key size?
-
- 1024 bit for DSA signatures; even for plain ElGamal signatures.
- This is sufficient as the size of the hash is probably the weakest
- link if the key size is larger than 1024 bits. Encryption keys may
- have greater sizes, but you should then check the fingerprint of
- this key:
-
- $ gpg --fingerprint <user ID>
-
- As for the key algorithms, you should stick with the default (i.e.,
- DSA signature and ElGamal encryption). An ElGamal signing key has
- the following disadvantages: the signature is larger, it is hard
- to create such a key useful for signatures which can withstand some
- real world attacks, you don't get any extra security compared to
- DSA, and there might be compatibility problems with certain PGP
- versions. It has only been introduced because at the time it was
- not clear whether there was a patent on DSA.
-
- 4.2) Why does it sometimes take so long to create keys?
-
- The problem here is that we need a lot of random bytes and for that
- we (on Linux the /dev/random device) must collect some random data.
- It is really not easy to fill the Linux internal entropy buffer; I
- talked to Ted Ts'o and he commented that the best way to fill the
- buffer is to play with your keyboard. Good security has its price.
- What I do is to hit several times on the shift, control, alternate,
- and caps lock keys, because these keys do not produce output to the
- screen. This way you get your keys really fast (it's the same thing
- PGP2 does).
-
- Another problem might be another program which eats up your random
- bytes (a program (look at your daemons) that reads from /dev/random).
-
- 4.3) And it really takes long when I work on a remote system. Why?
-
- Don't do this at all! You should never create keys or even use GnuPG
- on a remote system because you normally have no physical control
- over your secret key ring (which is in most cases vulnerable to
- advanced dictionary attacks) - I strongly encourage everyone to only
- create keys on a local computer (a disconnected laptop is probably
- the best choice) and if you need it on your connected box (I know,
- we all do this) be sure to have a strong password for both your
- account and for your secret key, and that you can trust your system
- administrator.
-
- When I check GnuPG on a remote system via ssh (I have no Alpha here)
- ;-) I have the same problem. It takes a *very* long time to create
- the keys, so I use a special option, --quick-random, to generate
- insecure keys which are only good for some tests.
-
- 4.4) What is the difference between options and commands?
-
- If you do a 'gpg --help', you will get two separate lists. The first
- is a list of commands. The second is a list of options. Whenever you
- run GPG, you must pick exactly one command (with one exception,
- see below). You may pick one or more options. The command should,
- just by convention, come at the end of the argument list, after all
- the options. If the command takes a file (all the basic ones do),
- the filename comes at the very end. So the basic way to run gpg is:
-
- $ gpg [--option something] [--option2] [--option3 something] --command file
-
- Some options take arguments. For example, the --output option (which
- can be abbreviated as -o) is an option that takes a filename. The
- option's argument must follow immediately after the option itself,
- otherwise gpg doesn't know which option the argument is supposed to
- paired with. As an option, --output and its filename must come before
- the command. The --recipient (-r) option takes a name or keyID to
- encrypt the message to, which must come right after the -r option.
- The --encrypt (or -e) command comes after all the options and is
- followed by the file you wish to encrypt. Therefore in this example
- the command-line issued would be:
-
- $ gpg -r alice -o secret.txt -e test.txt
-
- If you write the options out in full, it is easier to read:
-
- $ gpg --recipient alice --output secret.txt --encrypt test.txt
-
- If you're encrypting to a file with the extension ".txt", then you'd
- probably expect to see ASCII-armored text in the file (not binary),
- so you need to add the --armor (-a) option, which doesn't take any
- arguments:
-
- $ gpg --armor --recipient alice --output secret.txt --encrypt test.txt
-
- If you imagine square brackets around the optional parts, it becomes
- a bit clearer:
-
- $ gpg [--armor] [--recipient alice] [--output secret.txt] --encrypt test.txt
-
- The optional parts can be rearranged any way you want:
-
- $ gpg --output secret.txt --recipient alice --armor --encrypt test.txt
-
- If your filename begins with a hyphen (e.g. "-a.txt"), GnuPG assumes
- this is an option and may complain. To avoid this you have to either
- use "./-a.txt", or stop the option and command processing with two
- hyphens: "-- -a.txt".
-
- *The exception to using only one command:* signing and encrypting
- at the same time. For this you can combine both commands, such as in:
-
- $ gpg [--options] --sign --encrypt foo.txt
-
- 4.5) I can't delete a user ID on my secret keyring because it has
- already been deleted on my public keyring. What can I do?
-
- Because you can only select from the public key ring, there is no
- direct way to do this. However it is not very complicated to do
- anyway. Create a new user ID with exactly the same name and you
- will see that there are now two identical user IDs on the secret
- ring. Now select this user ID and delete it. Both user IDs will be
- removed from the secret ring.
-
- 4.6) I can't delete my secret key because the public key disappeared.
- What can I do?
-
- To select a key a search is always done on the public keyring,
- therefore it is not possible to select a secret key without
- having the public key. Normally it should never happen that the
- public key got lost but the secret key is still available. The
- reality is different, so GnuPG implements a special way to deal
- with it: Simply use the long keyID to specify the key to delete,
- which can be obtained by using the --with-colons options (it is
- the fifth field in the lines beginning with "sec").
-
- If you've lost your public key and need to recreate it instead
- for continued use with your secret key, you may be able to use
- gpgsplit as detailed in question 4.21.
-
- 4.7) What are trust, validity and ownertrust?
-
- With GnuPG, the term "ownertrust" is used instead of "trust" to
- help clarify that this is the value you have assigned to a key
- to express how much you trust the owner of this key to correctly
- sign (and thereby introduce) other keys. The "validity", or
- calculated trust, is a value which indicates how much GnuPG
- considers a key as being valid (that it really belongs to the
- one who claims to be the owner of the key). For more information
- on trust values see the chapter "The Web of Trust" in The GNU
- Privacy Handbook.
-
- 4.8) How do I sign a patch file?
-
- Use "gpg --clearsign --not-dash-escaped ...". The problem with
- --clearsign is that all lines starting with a dash are quoted with
- "- "; obviously diff produces many lines starting with a dash and
- these are then quoted and that is not good for a patch ;-). To use
- a patch file without removing the cleartext signature, the special
- option --not-dash-escaped may be used to suppress generation of
- these escape sequences. You should not mail such a patch because
- spaces and line endings are also subject to the signature and a
- mailer may not preserve these. If you want to mail a file you can
- simply sign it using your MUA (Mail User Agent).
-
- 4.9) Where is the "encrypt-to-self" option?
-
- Use "--encrypt-to your_keyID". You can use more than one of these
- options. To temporarily override the use of this additional key,
- you can use the option "--no-encrypt-to".
-
- 4.10) How can I get rid of the Version and Comment headers in armored
- messages?
-
- Use "--no-version --comment ''". Note that the left over blank line
- is required by the protocol.
-
- 4.11) What does the "You are using the xxxx character set." mean?
-
- This note is printed when UTF-8 mapping has to be done. Make sure
- that the displayed character set is the one you have activated on
- your system. Since "iso-8859-1" is the character set most used,
- this is the default. You can change the charset with the option
- "--charset". It is important that your active character set matches
- the one displayed - if not, restrict yourself to plain 7 bit ASCII
- and no mapping has to be done.
-
- 4.12) How can I get list of key IDs used to encrypt a message?
-
- $ gpg --batch --decrypt --list-only --status-fd 1 2>/dev/null |
- awk '/^\[GNUPG:\] ENC_TO / { print $3 }'
-
- 4.13) Why can't I decrypt files encrypted as symmetrical-only (-c) with
- a version of GnuPG prior to 1.0.1.
-
- There was a bug in GnuPG versions prior to 1.0.1 which affected files
- only if 3DES or Twofish was used for symmetric-only encryption (this has
- never been the default). The bug has been fixed, but to enable decryption
- of old files you should run gpg with the option "--emulate-3des-s2k-bug",
- decrypt the file and encrypt it again without this option.
-
- NOTE: This option was removed in GnuPG development version 1.1.0 and later
- updates, so you will need to use a version between 1.0.1 and 1.0.7 to
- re-encrypt any affected files.
-
- 4.14) How can I use GnuPG in an automated environment?
-
- You should use the option --batch and don't use passphrases as
- there is usually no way to store it more securely than on the
- secret keyring itself. The suggested way to create keys for an
- automated environment is:
-
- On a secure machine:
- If you want to do automatic signing, create a signing subkey
- for your key (use the interactive key editing menu by issueing
- the command 'gpg --edit-key keyID', enter "addkey" and select
- the DSA key type).
- Make sure that you use a passphrase (needed by the current
- implementation).
- gpg --export-secret-subkeys --no-comment foo >secring.auto
- Copy secring.auto and the public keyring to a test directory.
- Change to this directory.
- gpg --homedir . --edit foo and use "passwd" to remove the
- passphrase from the subkeys. You may also want to remove all
- unused subkeys.
- Copy secring.auto to a floppy and carry it to the target box.
-
- On the target machine:
- Install secring.auto as the secret keyring.
- Now you can start your new service. It's also a good idea to
- install an intrusion detection system so that you hopefully
- get a notice of an successful intrusion, so that you in turn
- can revoke all the subkeys installed on that machine and
- install new subkeys.
-
- 4.15) Which email-client can I use with GnuPG?
-
- Using GnuPG to encrypt email is one of the most popular uses.
- Several mail clients or mail user agents (MUAs) support GnuPG to
- varying degrees. Simplifying a bit, there are two ways mail can be
- encrypted with GnuPG: the "old style" ASCII armor (i.e. cleartext
- encryption), and RFC 2015 style (previously PGP/MIME, now OpenPGP).
- The latter has full MIME support. Some MUAs support only one of
- them, so whichever you actually use depends on your needs as well
- as the capabilities of your addressee. As well, support may be
- native to the MUA, or provided via "plug-ins" or external tools.
-
- The following list is not exhaustive:
-
- MUA OpenPGP ASCII How? (N,P,T)
- -------------------------------------------------------------
- Calypso N Y P (Unixmail)
- Elm N Y T (mailpgp,morepgp)
- Elm ME+ N Y N
- Emacs/Gnus Y Y T (Mailcrypt,gpg.el)
- Emacs/Mew Y Y N
- Emacs/VM N Y T (Mailcrypt)
- Evolution Y Y N
- Exmh Y Y N
- GNUMail.app Y Y P (PGPBundle)
- GPGMail Y Y N
- KMail (<=1.4.x) N Y N
- KMail (1.5.x) Y(P) Y(N) P/N
- Mozilla Y Y P (Enigmail)
- Mulberry Y Y P
- Mutt Y Y N
- Sylpheed Y Y N
- Sylpheed-claws Y Y N
- TkRat Y Y N
- XEmacs/Gnus Y Y T (Mailcrypt)
- XEmacs/Mew Y Y N
- XEmacs/VM N Y T (Mailcrypt)
- XFmail Y Y N
-
- N - Native, P - Plug-in, T - External Tool
-
- The following table lists proprietary MUAs. The GNU Project
- suggests against the use of these programs, but they are listed
- for interoperability reasons for your convenience.
-
- MUA OpenPGP ASCII How? (N,P,T)
- -------------------------------------------------------------
- Apple Mail Y Y P (GPGMail)
- Becky2 Y Y P (BkGnuPG)
- Eudora Y Y P (EuroraGPG)
- Eudora Pro Y Y P (EudoraGPG)
- Lotus Notes N Y P
- Netscape 4.x N Y P
- Netscape 7.x Y Y P (Enigmail)
- Novell Groupwise N Y P
- Outlook N Y P (G-Data)
- Outlook Express N Y P (GPGOE)
- Pegasus N Y P (QDPGP,PM-PGP)
- Pine N Y T (pgpenvelope,(gpg|pgp)4pine)
- Postme N Y P (GPGPPL)
- The Bat! N Y P (Ritlabs)
-
- Good overviews of OpenPGP-support can be found at:
- <http://www.openpgp.fr.st/courrier_en.html> and
- <http://www.bretschneidernet.de/tips/secmua.html>.
-
- Users of Win32 MUAs that lack OpenPGP support may look into
- using GPGrelay <http://gpgrelay.sourceforge.net>, a small
- email-relaying server that uses GnuPG to enable many email clients
- to send and receive emails that conform to PGP-MIME (RFC 2015).
-
- 4.16) Can't we have a gpg library?
-
- This has been frequently requested. However, the current viewpoint
- of the GnuPG maintainers is that this would lead to several security
- issues and will therefore not be implemented in the foreseeable
- future. However, for some areas of application gpgme could do the
- trick. You'll find it at <ftp://ftp.gnupg.org/gcrypt/alpha/gpgme>.
-
- 4.17) I have successfully generated a revocation certificate, but I don't
- understand how to send it to the key servers.
-
- Most keyservers don't accept a 'bare' revocation certificate. You
- have to import the certificate into gpg first:
-
- $ gpg --import my-revocation.asc
-
- then send the revoked key to the keyservers:
-
- $ gpg --keyserver certserver.pgp.com --send-keys mykeyid
-
- (or use a keyserver web interface for this).
-
- 4.18) How do I put my keyring in a different directory?
-
- GnuPG keeps several files in a special homedir directory. These
- include the options file, pubring.gpg, secring.gpg, trustdb.gpg,
- and others. GnuPG will always create and use these files. On unices,
- the homedir is usually ~/.gnupg; on Windows "C:\gnupg\".
-
- If you want to put your keyrings somewhere else, use the option:
-
- --homedir /my/path/
-
- to make GnuPG create all its files in that directory. Your keyring
- will be "/my/path/pubring.gpg". This way you can store your secrets
- on a floppy disk. Don't use "--keyring" as its purpose is to specify
- additional keyring files.
-
- 4.19) How do I verify signed packages?
-
- Before you can verify the signature that accompanies a package,
- you must first have the vendor, organisation, or issueing person's
- key imported into your public keyring. To prevent GnuPG warning
- messages the key should also be validated (or locally signed).
-
- You will also need to download the detached signature file along
- with the package. These files will usually have the same name as
- the package, with either a binary (.sig) or ASCII armor (.asc)
- extension.
-
- Once their key has been imported, and the package and accompanying
- signature files have been downloaded, use:
-
- $ gpg --verify sigfile signed-file
-
- If the signature file has the same base name as the package file,
- the package can also be verified by specifying just the signature
- file, as GnuPG will derive the package's file name from the name
- given (less the .sig or .asc extension). For example, to verify a
- package named foobar.tar.gz against its detached binary signature
- file, use:
-
- $ gpg --verify foobar.tar.gz.sig
-
- 4.20) How do I export a keyring with only selected signatures (keys)?
-
- If you're wanting to create a keyring with only a subset of keys
- selected from a master keyring (for a club, user group, or company
- department for example), simply specify the keys you want to export:
-
- $ gpg --armor --export key1 key2 key3 key4 > keys1-4.asc
-
- 4.21) I still have my secret key, but lost my public key. What can I do?
-
- All OpenPGP secret keys have a copy of the public key inside them,
- and in a worst-case scenario, you can create yourself a new public
- key using the secret key.
-
- A tool to convert a secret key into a public one has been included
- (it's actually a new option for gpgsplit) and is available with GnuPG
- versions 1.2.1 or later (or can be found in CVS). It works like this:
-
- $ gpgsplit --no-split --secret-to-public secret.gpg >publickey.gpg
-
- One should first try to export the secret key and convert just this
- one. Using the entire secret keyring should work too. After this has
- been done, the publickey.gpg file can be imported into GnuPG as usual.
-
- 4.22) Clearsigned messages sent from my web-mail account have an invalid
- signature. Why?
-
- Check to make sure the settings for your web-based email account
- do not use HTML formatting for the pasted clearsigned message. This can
- alter the message with embedded HTML markup tags or spaces, resulting
- in an invalid signature. The recipient may be able to copy the signed
- message block to a text file for verification, or the web email
- service may allow you to attach the clearsigned message as a file
- if plaintext messages are not an option.
-
-
- 5. COMPATIBILITY ISSUES
-
- 5.1) How can I encrypt a message with GnuPG so that PGP is able to decrypt it?
-
- It depends on the PGP version.
-
- PGP 2.x
- You can't do that because PGP 2.x normally uses IDEA which is not
- supported by GnuPG as it is patented (see 3.3), but if you have a
- modified version of PGP you can try this:
-
- $ gpg --rfc1991 --cipher-algo 3des ...
-
- Please don't pipe the data to encrypt to gpg but provide it using a
- filename; otherwise, PGP 2 will not be able to handle it.
-
- As for conventional encryption, you can't do this for PGP 2.
-
- PGP 5.x and higher
- You need to provide two additional options:
-
- --compress-algo 1 --cipher-algo cast5
-
- You may also use "3des" instead of "cast5", and "blowfish" does not
- work with all versions of PGP 5. You may also want to put:
-
- compress-algo 1
-
- into your ~/.gnupg/options file - this does not affect normal GnuPG
- operation.
-
- This applies to conventional encryption as well.
-
- 5.2) How do I migrate from PGP 2.x to GnuPG?
-
- PGP 2 uses the RSA and IDEA encryption algorithms. Whereas the RSA
- patent has expired and RSA is included as of GnuPG 1.0.3, the IDEA
- algorithm is still patented until 2007. Under certain conditions you
- may use IDEA even today. In that case, you may refer to Question
- 3.3 about how to add IDEA support to GnuPG and read
- <http://www.gnupg.org/gph/en/pgp2x.html> to perform the migration.
-
- 5.3) (removed)
-
- (empty)
-
- 5.4) Why is PGP 5.x not able to encrypt messages with some keys?
-
- PGP, Inc. refuses to accept ElGamal keys of type 20 even for
- encryption. They only support type 16 (which is identical at least
- for decryption). To be more inter-operable, GnuPG (starting with
- version 0.3.3) now also uses type 16 for the ElGamal subkey which is
- created if the default key algorithm is chosen. You may add a type
- 16 ElGamal key to your public key, which is easy as your key
- signatures are still valid.
-
- 5.5) Why is PGP 5.x not able to verify my messages?
-
- PGP 5.x does not accept v4 signatures for data material but OpenPGP
- requests generation of v4 signatures for all kind of data, that's why
- GnuPG defaults to them. Use the option "--force-v3-sigs" to generate
- v3 signatures for data.
-
- 5.6) How do I transfer owner trust values from PGP to GnuPG?
-
- There is a script in the tools directory to help you. After you have
- imported the PGP keyring you can give this command:
-
- $ lspgpot pgpkeyring | gpg --import-ownertrust
-
- where pgpkeyring is the original keyring and not the GnuPG keyring
- you might have created in the first step.
-
- 5.7) PGP does not like my secret key.
-
- Older PGPs probably bail out on some private comment packets used by
- GnuPG. These packets are fully in compliance with OpenPGP; however
- PGP is not really OpenPGP aware. A workaround is to export the
- secret keys with this command:
-
- $ gpg --export-secret-keys --no-comment -a your-KeyID
-
- Another possibility is this: by default, GnuPG encrypts your secret
- key using the Blowfish symmetric algorithm. Older PGPs will only
- understand 3DES, CAST5, or IDEA symmetric algorithms. Using the
- following method you can re-encrypt your secret gpg key with a
- different algo:
-
- $ gpg --s2k-cipher-algo=CAST5 --s2k-digest-algo=SHA1
- --compress-algo=1 --edit-key <username>
-
- Then use passwd to change the password (just change it to the same
- thing, but it will encrypt the key with CAST5 this time).
-
- Now you can export it and PGP should be able to handle it.
-
- For PGP 6.x the following options work to export a key:
-
- $ gpg --s2k-cipher-algo 3des --compress-algo 1 --rfc1991
- --export-secret-keys <KeyID>
-
- 5.8) GnuPG no longer installs a ~/.gnupg/options file. Is it missing?
-
- No. The ~/.gnupg/options file has been renamed to ~/.gnupg/gpg.conf for
- new installs as of version 1.1.92. If an existing ~/.gnupg/options file
- is found during an upgrade it will still be used, but this change was
- required to have a more consistent naming scheme with forthcoming tools.
- An existing options file can be renamed to gpg.conf for users upgrading,
- or receiving the message that the "old default options file" is ignored
- (occurs if both a gpg.conf and an options file are found).
-
- 5.9) How do you export GnuPG keys for use with PGP?
-
- This has come up fairly often, so here's the HOWTO:
-
- PGP can (for most key types) use secret keys generated by GnuPG. The
- problems that come up occasionally are generally because GnuPG
- supports a few more features from the OpenPGP standard than PGP does.
- If your secret key has any of those features in use, then PGP will
- reject the key or you will have problems communicating later. Note
- that PGP doesn't do ElGamal signing keys at all, so they are not
- usable with any version.
-
- These instructions should work for GnuPG 1.0.7 and later, and PGP
- 7.0.3 and later.
-
- Start by editing the key. Most of this line is not really necessary
- as the default values are correct, but it does not hurt to repeat the
- values, as this will override them in case you have something else set
- in your options file.
-
- $ gpg --s2k-cipher-algo cast5 --s2k-digest-algo sha1 --s2k-mode 3
- --simple-sk-checksum --edit KeyID
-
- Turn off some features. Set the list of preferred ciphers, hashes,
- and compression algorithms to things that PGP can handle. (Yes, I
- know this is an odd list of ciphers, but this is what PGP itself uses,
- minus IDEA).
-
- > setpref S9 S8 S7 S3 S2 S10 H2 H3 Z1 Z0
-
- Now put the list of preferences onto the key.
-
- > updpref
-
- Finally we must decrypt and re-encrypt the key, making sure that we
- encrypt with a cipher that PGP likes. We set this up in the --edit
- line above, so now we just need to change the passphrase to make it
- take effect. You can use the same passphrase if you like, or take
- this opportunity to actually change it.
-
- > passwd
-
- Save our work.
-
- > save
-
- Now we can do the usual export:
-
- $ gpg --export KeyID > mypublickey.pgp
- $ gpg --export-secret-key KeyID > mysecretkey.pgp
-
- Thanks to David Shaw for this information!
-
-
- 6. PROBLEMS and ERROR MESSAGES
-
- 6.1) Why do I get "gpg: Warning: using insecure memory!"
-
- On many systems this program should be installed as setuid(root).
- This is necessary to lock memory pages. Locking memory pages prevents
- the operating system from writing them to disk and thereby keeping your
- secret keys really secret. If you get no warning message about insecure
- memory your operating system supports locking without being root. The
- program drops root privileges as soon as locked memory is allocated.
-
- To setuid(root) permissions on the gpg binary you can either use:
-
- $ chmod u+s /path/to/gpg
-
- or
-
- $ chmod 4755 /path/to/gpg
-
- Some refrain from using setuid(root) unless absolutely required for
- security reasons. Please check with your system administrator if you
- are not able to make these determinations yourself.
-
- On UnixWare 2.x and 7.x you should install GnuPG with the 'plock'
- privilege to get the same effect:
-
- $ filepriv -f plock /path/to/gpg
-
- If you can't or don't want to install GnuPG setuid(root), you can
- use the option "--no-secmem-warning" or put:
-
- no-secmem-warning
-
- in your ~/.gnupg/options or ~/.gnupg/gpg.conf file (this disables
- the warning).
-
- On some systems (e.g., Windows) GnuPG does not lock memory pages
- and older GnuPG versions (<=1.0.4) issue the warning:
-
- gpg: Please note that you don't have secure memory
-
- This warning can't be switched off by the above option because it
- was thought to be too serious an issue. However, it confused users
- too much, so the warning was eventually removed.
-
- 6.2) Large File Support doesn't work ...
-
- LFS works correctly in post-1.0.4 versions. If configure doesn't
- detect it, try a different (i.e., better) compiler. egcs 1.1.2 works
- fine, other gccs sometimes don't. BTW, several compilation problems
- of GnuPG 1.0.3 and 1.0.4 on HP-UX and Solaris were due to broken LFS
- support.
-
- 6.3) In the edit menu the trust values are not displayed correctly after
- signing uids. Why?
-
- This happens because some information is stored immediately in
- the trustdb, but the actual trust calculation can be done after the
- save command. This is a "not easy to fix" design bug which will be
- addressed in some future release.
-
- 6.4) What does "skipping pubkey 1: already loaded" mean?
-
- As of GnuPG 1.0.3, the RSA algorithm is included. If you still have
- a "load-extension rsa" in your options file, the above message
- occurs. Just remove the load command from the options file.
-
- 6.5) GnuPG 1.0.4 doesn't create ~/.gnupg ...
-
- That's a known bug, already fixed in newer versions.
-
- 6.6) An ElGamal signature does not verify anymore since version 1.0.2 ...
-
- Use the option --emulate-md-encode-bug.
-
- 6.7) Old versions of GnuPG can't verify ElGamal signatures
-
- Update to GnuPG 1.0.2 or newer.
-
- 6.8) When I use --clearsign, the plain text has sometimes extra dashes
- in it - why?
-
- This is called dash-escaped text and is required by OpenPGP.
- It always happens when a line starts with a dash ("-") and is
- needed to make the lines that structure signature and text
- (i.e., "-----BEGIN PGP SIGNATURE-----") to be the only lines
- that start with two dashes.
-
- If you use GnuPG to process those messages, the extra dashes
- are removed. Good mail clients remove those extra dashes when
- displaying such a message.
-
- 6.9) What is the thing with "can't handle multiple signatures"?
-
- Due to different message formats GnuPG is not always able to split
- a file with multiple signatures unambiguously into its parts. This
- error message informs you that there is something wrong with the input.
-
- The only way to have multiple signatures in a file is by using the
- OpenPGP format with one-pass-signature packets (which is GnuPG's
- default) or the cleartext signed format.
-
- 6.10) If I submit a key to a keyserver, nothing happens ...
-
- You are most likely using GnuPG 1.0.2 or older on Windows. That's
- feature isn't yet implemented, but it's a bug not to say it. Newer
- versions issue a warning. Upgrade to 1.0.4 or newer.
-
- 6.11) I get "gpg: waiting for lock ..."
-
- A previous instance of gpg has most likely exited abnormally and left
- a lock file. Go to ~/.gnupg and look for .*.lock files and remove them.
-
- 6.12) Older gpg binaries (e.g., 1.0) have problems with keys from newer
- gpg binaries ...
-
- As of 1.0.3, keys generated with gpg are created with preferences to
- TWOFISH (and AES since 1.0.4) and that also means that they have the
- capability to use the new MDC encryption method. This will go into
- OpenPGP soon, and is also suppoted by PGP 7. This new method avoids
- a (not so new) attack on all email encryption systems.
-
- This in turn means that pre-1.0.3 gpg binaries have problems with
- newer keys. Because of security and bug fixes, you should keep your
- GnuPG installation in a recent state anyway. As a workaround, you can
- force gpg to use a previous default cipher algo by putting:
-
- cipher-algo cast5
-
- into your options file.
-
- 6.13) With 1.0.4, I get "this cipher algorithm is deprecated ..."
-
- If you just generated a new key and get this message while
- encrypting, you've witnessed a bug in 1.0.4. It uses the new AES
- cipher Rijndael that is incorrectly being referred as "deprecated".
- Ignore this warning, more recent versions of gpg are corrected.
-
- 6.14) Some dates are displayed as ????-??-??. Why?
-
- Due to constraints in most libc implementations, dates beyond
- 2038-01-19 can't be displayed correctly. 64-bit OSes are not
- affected by this problem. To avoid printing wrong dates, GnuPG
- instead prints some question marks. To see the correct value, you
- can use the options --with-colons and --fixed-list-mode.
-
- 6.15) I still have a problem. How do I report a bug?
-
- Are you sure that it's not been mentioned somewhere on the mailing
- lists? Did you have a look at the bug list (you'll find a link to
- the list of reported bugs on the documentation page). If you're not
- sure about it being a bug, you can send mail to the gnupg-devel
- list. Otherwise, use the GUUG bug tracking system
- <http://bugs.guug.de/Reporting.html>.
-
- 6.16) Why doesn't GnuPG support X.509 certificates?
-
- GnuPG, first and foremost, is an implementation of the OpenPGP
- standard (RFC 2440), which is a competing infrastructure, different
- from X.509.
-
- They are both public-key cryptosystems, but how the public keys are
- actually handled is different.
-
- 6.17) Why do national characters in my user ID look funny?
-
- According to OpenPGP, GnuPG encodes user ID strings (and other
- things) using UTF-8. In this encoding of Unicode, most national
- characters get encoded as two- or three-byte sequences. For
- example, å (0xE5 in ISO-8859-1) becomes Ã¥ (0xC3,
- 0xA5). This might also be the reason why keyservers can't find
- your key.
-
- 6.18) I get 'sed' errors when running ./configure on Mac OS X ...
-
- This will be fixed after GnuPG has been upgraded to autoconf-2.50.
- Until then, find the line setting CDPATH in the configure script
- and place an:
-
- unset CDPATH
-
- statement below it.
-
- 6.19) Why does GnuPG 1.0.6 bail out on keyrings used with 1.0.7?
-
- There is a small bug in 1.0.6 which didn't parse trust packets
- correctly. You may want to apply this patch if you can't upgrade:
-
- <http://www.gnupg.org/developer/gpg-woody-fix.txt>
-
- 6.20) I upgraded to GnuPG version 1.0.7 and now it takes longer to load my
- keyrings. What can I do?
-
- The way signature states are stored has changed so that v3 signatures
- can be supported. You can use the new --rebuild-keydb-caches migration
- command, which was built into this release and increases the speed of
- many operations for existing keyrings.
-
- 6.21) Doesn't a fully trusted user ID on a key prevent warning messages
- when encrypting to other IDs on the key?
-
- No. That was actually a key validity bug in GnuPG 1.2.1 and earlier
- versions. As part of the development of GnuPG 1.2.2, a bug was
- discovered in the key validation code. This bug causes keys with
- more than one user ID to give all user IDs on the key the amount of
- validity given to the most-valid key. The bug has been fixed in GnuPG
- release 1.2.2, and upgrading is the recommended fix for this problem.
- More information and a patch for a some pre-1.2.2 versions of GnuPG
- can be found at:
-
- <http://lists.gnupg.org/pipermail/gnupg-announce/2003q2/000268.html>
-
- 6.22) I just compiled GnuPG from source on my GNU/Linux RPM-based system
- and it's not working. Why?
-
- Many GNU/Linux distributions that are RPM-based will install a
- version of GnuPG as part of its standard installation, placing the
- binaries in the /usr/bin directory. Later, compiling and installing
- GnuPG from source other than from a source RPM won't normally
- overwrite these files, as the default location for placement of
- GnuPG binaries is in /usr/local/bin unless the '--prefix' switch
- is used during compile to specify an alternate location. Since the
- /usr/bin directory more than likely appears in your path before
- /usr/local/bin, the older RPM-version binaries will continue to
- be used when called since they were not replaced.
-
- To resolve this, uninstall the RPM-based version with 'rpm -e gnupg'
- before installing the binaries compiled from source. If dependency
- errors are displayed when attempting to uninstall the RPM (such as
- when Red Hat's up2date is also installed, which uses GnuPG), uninstall
- the RPM with 'rpm -e gnupg --nodeps' to force the uninstall. Any
- dependent files should be automatically replaced during the install
- of the compiled version. If the default /usr/local/bin directory is
- used, some packages such as SuSE's Yast Online Update may need to be
- configured to look for GnuPG binaries in the /usr/local/bin directory,
- or symlinks can be created in /usr/bin that point to the binaries
- located in /usr/local/bin.
-
-
- 7. ADVANCED TOPICS
-
- 7.1) How does this whole thing work?
-
- To generate a secret/public keypair, run:
-
- $ gpg --gen-key
-
- and choose the default values.
-
- Data that is encrypted with a public key can only be decrypted by
- the matching secret key. The secret key is protected by a password,
- the public key is not.
-
- So to send your friend a message, you would encrypt your message
- with his public key, and he would only be able to decrypt it by
- having the secret key and putting in the password to use his secret
- key.
-
- GnuPG is also useful for signing things. Files that are encrypted
- with the secret key can be decrypted with the public key. To sign
- something, a hash is taken of the data, and then the hash is in some
- form encoded with the secret key. If someone has your public key, they
- can verify that it is from you and that it hasn't changed by checking
- the encoded form of the hash with the public key.
-
- A keyring is just a large file that stores keys. You have a public
- keyring where you store yours and your friend's public keys. You have
- a secret keyring that you keep your secret key on, and should be very
- careful with. Never ever give anyone else access to it and use a *good*
- passphrase to protect the data in it.
-
- You can 'conventionally' encrypt something by using the option 'gpg -c'.
- It is encrypted using a passphrase, and does not use public and secret
- keys. If the person you send the data to knows that passphrase, they
- can decrypt it. This is usually most useful for encrypting things to
- yourself, although you can encrypt things to your own public key in the
- same way. It should be used for communication with partners you know
- and where it is easy to exchange the passphrases (e.g. with your boy
- friend or your wife). The advantage is that you can change the
- passphrase from time to time and decrease the risk, that many old
- messages may be decrypted by people who accidently got your passphrase.
-
- You can add and copy keys to and from your keyring with the 'gpg
- --import' and 'gpg --export' option. 'gpg --export-secret-keys' will
- export secret keys. This is normally not useful, but you can generate
- the key on one machine then move it to another machine.
-
- Keys can be signed under the 'gpg --edit-key' option. When you sign a
- key, you are saying that you are certain that the key belongs to the
- person it says it comes from. You should be very sure that is really
- that person: You should verify the key fingerprint with:
-
- $ gpg --fingerprint KeyID
-
- over the phone (if you really know the voice of the other person), at
- a key signing party (which are often held at computer conferences),
- or at a meeting of your local GNU/Linux User Group.
-
- Hmm, what else. You may use the option '-o filename' to force output
- to this filename (use '-' to force output to stdout). '-r' just lets
- you specify the recipient (which public key you encrypt with) on the
- command line instead of typing it interactively.
-
- Oh yeah, this is important. By default all data is encrypted in some
- weird binary format. If you want to have things appear in ASCII text
- that is readable, just add the '-a' option. But the preferred method
- is to use a MIME aware mail reader (Mutt, Pine and many more).
-
- There is a small security glitch in the OpenPGP (and therefore GnuPG)
- system; to avoid this you should always sign and encrypt a message
- instead of only encrypting it.
-
- 7.2) Why are some signatures with an ELG-E key valid?
-
- These are ElGamal keys generated by GnuPG in v3 (RFC 1991) packets.
- The OpenPGP draft later changed the algorithm identifier for ElGamal
- keys which are usable for signatures and encryption from 16 to 20.
- GnuPG now uses 20 when it generates new ElGamal keys but still
- accepts 16 (which is according to OpenPGP "encryption only") if this
- key is in a v3 packet. GnuPG is the only program which had used
- these v3 ElGamal keys - so this assumption is quite safe.
-
- 7.3) How does the whole trust thing work?
-
- It works more or less like PGP. The difference is that the trust is
- computed at the time it is needed. This is one of the reasons for
- the trustdb which holds a list of valid key signatures. If you are
- not running in batch mode you will be asked to assign a trust
- parameter (ownertrust) to a key.
-
- You can see the validity (calculated trust value) using this
- command.
-
- $ gpg --list-keys --with-colons
-
- If the first field is "pub" or "uid", the second field shows you the
- trust:
-
- o = Unknown (this key is new to the system)
- e = The key has expired
- q = Undefined (no value assigned)
- n = Don't trust this key at all
- m = There is marginal trust in this key
- f = The key is full trusted
- u = The key is ultimately trusted; this is only used
- for keys for which the secret key is also available.
- r = The key has been revoked
- d = The key has been disabled
-
- The value in the "pub" record is the best one of all "uid" records.
- You can get a list of the assigned trust values (how much you trust
- the owner to correctly sign another person's key) with:
-
- $ gpg --list-ownertrust
-
- The first field is the fingerprint of the primary key, the second
- field is the assigned value:
-
- - = No ownertrust value yet assigned or calculated.
- n = Never trust this keyholder to correctly verify others signatures.
- m = Have marginal trust in the keyholders capability to sign other
- keys.
- f = Assume that the key holder really knows how to sign keys.
- u = No need to trust ourself because we have the secret key.
-
- Keep these values confidential because they express your opinions
- about others. PGP stores this information with the keyring thus it
- is not a good idea to publish a PGP keyring instead of exporting the
- keyring. GnuPG stores the trust in the trustdb.gpg file so it is okay
- to give a gpg keyring away (but we have a --export command too).
-
- 7.4) What kind of output is this: "key C26EE891.298, uid 09FB: ...."?
-
- This is the internal representation of a user ID in the trustdb.
- "C26EE891" is the keyid, "298" is the local ID (a record number in
- the trustdb) and "09FB" is the last two bytes of a ripe-md-160 hash
- of the user ID for this key.
-
- 7.5) How do I interpret some of the informational outputs?
-
- While checking the validity of a key, GnuPG sometimes prints some
- information which is prefixed with information about the checked
- item.
-
- "key 12345678.3456"
-
- This is about the key with key ID 12345678 and the internal number
- 3456, which is the record number of the so called directory record
- in the trustdb.
-
- "uid 12345678.3456/ACDE"
-
- This is about the user ID for the same key. To identify the user ID
- the last two bytes of a ripe-md-160 over the user ID ring is printed.
-
- "sig 12345678.3456/ACDE/9A8B7C6D"
-
- This is about the signature with key ID 9A8B7C6D for the above key
- and user ID, if it is a signature which is direct on a key, the user
- ID part is empty (..//..).
-
- 7.6) Are the header lines of a cleartext signature part of the signed
- material?
-
- No. For example you can add or remove "Comment:" lines. They have
- a purpose like the mail header lines. However a "Hash:" line is
- needed for OpenPGP signatures to tell the parser which hash
- algorithm to use.
-
- 7.7) What is the list of preferred algorithms?
-
- The list of preferred algorithms is a list of cipher, hash and
- compression algorithms stored in the self-signature of a key during
- key generation. When you encrypt a document, GnuPG uses this list
- (which is then part of a public key) to determine which algorithms
- to use. Basically it tells other people what algorithms the
- recipient is able to handle and provides an order of preference.
-
- 7.8) How do I change the list of preferred algorithms?
-
- In version 1.0.7 or later, you can use the edit menu and set the
- new list of preference using the command "setpref"; the format of
- this command resembles the output of the command "pref". The
- preference is not changed immediately but the set preference will
- be used when a new user ID is created. If you want to update the
- preferences for existing user IDs, select those user IDs (or select
- none to update all) and enter the command "updpref". Note that the
- timestamp of the self-signature is increased by one second when
- running this command.
-
-
- 8. ACKNOWLEDGEMENTS
-
- Many thanks to Nils Ellmenreich for maintaining this FAQ file for
- such a long time, Werner Koch for the original FAQ file, and to all
- posters to gnupg-users and gnupg-devel. They all provided most of
- the answers.
-
- Also thanks to Casper Dik for providing us with a script to generate
- this FAQ (he uses it for the excellent Solaris2 FAQ).
-
-
- Copyright (C) 2000, 2001, 2002, 2003 Free Software Foundation, Inc.,
- 59 Temple Place - Suite 330, Boston, MA 02111, USA
-
- Verbatim copying and distribution of this entire article is permitted in
- any medium, provided this notice is preserved.