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diff --git a/doc/faq.raw b/doc/faq.raw deleted file mode 100644 index ec4212326..000000000 --- a/doc/faq.raw +++ /dev/null @@ -1,1019 +0,0 @@ -[$htmltitle=GnuPG FAQ] -[$sfaqheader=The GnuPG FAQ says:] -[$sfaqfooter= -The most recent version of the FAQ is available from -<http://www.gnupg.org/> -] -[$usenetheader= -] -[$maintainer=David D. Scribner, <faq 'at' gnupg.org>] -[$hGPG=http://www.gnupg.org] - -[H body bgcolor=#ffffff text=#000000 link=#1f00ff alink=#ff0000 vlink=#9900dd] -[H H1]GnuPG Frequently Asked Questions[H /H1] - - -[H p] -Version: 1.5.7[H br] -Last-Modified: Aug 21, 2002[H br] -Maintained-by: [$maintainer] -[H /p] - - -This is the GnuPG FAQ. The latest HTML version is available -[H a href=[$hGPG]/faq.html]here[H/a]. - -The index is generated automatically, so there may be errors here. 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. - -[H HR] -<C> -[H HR] - - -<S> GENERAL - -<Q> What is GnuPG? - - [H a href=[$hGPG]]GnuPG[H /a] stands for GNU Privacy Guard and - is GNU's tool for secure communication and data storage. It can be - used to encrypt data and to create digital signatures. It includes - an advanced key management facility and is compliant with the - proposed OpenPGP Internet standard as described in [H a href=http://www.gnupg.org/rfc2440.html]RFC 2440[H/a]. - As such, it is aimed to be compatible with PGP from NAI, Inc. - -<Q> Is GnuPG compatible with PGP? - - In general, yes. GnuPG and newer PGP releases should be implementing - the OpenPGP standard. But there are some interoperability - problems. See question <Rcompat> for details. - - -<S> SOURCES of INFORMATION - -<Q> Where can I find more information? - - Here's a list of on-line resources: - - [H UL] - [H LI]The documentation page is located at [H a href=[$hGPG]/docs.html]<[$hGPG]/docs.html>[H/a]. - Have a look at the HOWTOs and the GNU Privacy Handbook (GPH, available - in English, Spanish and Russian). The latter provides a detailed user's - guide to GnuPG. You'll also find a document about how to convert from - PGP 2.x to GnuPG. - - [H LI]On [H a href=http://lists.gnupg.org]<http://lists.gnupg.org>[H/a] you'll find an online archive of the - GnuPG mailing lists. Most interesting should be gnupg-users for all - user-related issues and gnupg-devel if you want to get in touch with - the developers. - - In addition, searchable archives can be found on MARC, e.g.: [H br] - GnuPG-users: [H a href=http://marc.theaimsgroup.com/?l=gnupg-users&r=1&w=2]<http://marc.theaimsgroup.com/?l=gnupg-users&r=1&w=2>[H/a],[H br] - GnuPG-devel: [H a href=http://marc.theaimsgroup.com/?l=gnupg-devel&r=1&w=2]<http://marc.theaimsgroup.com/?l=gnupg-devel&r=1&w=2>[H/a].[H br] - - [H B]PLEASE:[H/B] - Before posting to a list, read this FAQ and the available - documentation. In addition, search the list archive - maybe your - question has already been discussed. This way you help people focus - on topics that have not yet been resolved. - - [H LI]The GnuPG source distribution contains a subdirectory: - - [H PRE] - ./doc - [H /PRE] - - where some additional documentation is located (mainly interesting - for hackers, not the casual user). - [H /UL] - -<Q> Where do I get GnuPG? - - You can download the GNU Privacy Guard from its primary FTP server - [H a href=ftp://ftp.gnupg.org/pub/gcrypt]ftp.gnupg.org[H /a] or from one of the mirrors: - - [H a href=[$hGPG]/mirrors.html] - <[$hGPG]/mirror.html> - [H /a] - - The current version is 1.0.4, please upgrade to this version as it - fixes a security bug regarding the verification of multiple signatures. - - -<S> INSTALLATION - -<Q> Which OSes does GnuPG run on? - - It should run on most Unices as well as Windows 95 and Windows NT. A - list of OSes reported to be OK is presented at: - - [H a href=http://www.gnupg.org/backend.html#supsys] - <http://www.gnupg.org/gnupg.html#supsys> - [H /a] - -<Q> Which random 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: - - [H pre] - --enable-static-rnd=linux - [H/pre] - - In addition, there's also the kernel random device by Andi Maier - [H a href= http://www.cosy.sbg.ac.at/~andi]<http://www.cosy.sbg.ac.at/~andi>[H /a], 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 [H a href=http://www.gnupg.org/download.html]<http://www.gnupg.org/download.html>[H /a] - to obtain egd. Use: - - [H pre] - --enable-static-rnd=egd - [H/pre] - - here. - - If the above options do not work, you can use the random number - generator "unix". This is [H B]very[H /B] slow and should be avoiced. The - random quality isn't very good so don't use it on sensitive data. - -<Didea> -<Q> How do I include support for RSA and IDEA? - - RSA is included as of GnuPG 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 - [H a href=ftp://ftp.gnupg.org/pub/gcrypt/contrib/]<ftp://ftp.gnupg.org/pub/gcrypt/contrib/>[H /a]. Look for: - - [H pre] - idea.c - [H /pre] - - Compilation directives are in the headers of these files. Then add - the following line to your ~/.gnupg/options: - - [H pre] - load-extension idea - [H /pre] - - -<S> USAGE - -<Q> 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: - - [H pre] - gpg --fingerprint <user ID> - [H /pre] - - As for the key algorithms, you should stick with the default (i.e., - DSA signature and ElGamal encryption). A 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. - -<Q> 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). - -<Q> 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 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. - -<Q> 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 [H B]must[H /B] pick exactly one command (with one exception, - see below). You [H B]may[H /B] 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: - - [H pre] - gpg [--option something] [--option2] [--option3 something] --command file - [H/pre] - - Some options take arguments. For example, the --output option (which - can be abbreviated -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 - go 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 argument. - The --encrypt (or -e) command comes after all the options followed - by the file you wish to encrypt. So use: - - [H pre] - gpg -r alice -o secret.txt -e test.txt - [H/pre] - - If you write the options out in full, it is easier to read: - - [H pre] - gpg --recipient alice --output secret.txt --encrypt test.txt - [H/pre] - - If you're saving it in a file called ".txt" then you'd probably - expect to see ASCII-armored text in there, so you need to add the - --armor (-a) option, which doesn't take any arguments: - - [H pre] - gpg --armor --recipient alice --output secret.txt --encrypt test.txt - [H/pre] - - If you imagine square brackets around the optional parts, it becomes - a bit clearer: - - [H pre] - gpg [--armor] [--recipient alice] [--output secret.txt] --encrypt test.txt - [H/pre] - - The optional parts can be rearranged any way you want: - - [H pre] - gpg --output secret.txt --recipient alice --armor --encrypt test.txt - [H/pre] - - 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 either - to use "./-a.txt" or stop the option and command processing with two - hyphens: "-- -a.txt". [H B]The exception:[H /B] signing and encrypting at the - same time. Use: - - [H pre] - gpg [--options] --sign --encrypt foo.txt - [H/pre] - -<Q> I can't delete a user ID because it is already deleted on my public - keyring? - - 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. - -<Q> I can't delete the secret key because my public key disappeared? - - To select a key a search is always done on the public keyring, - therefore it is not possible to select an secret key without - having the public key. Normally it shoud 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 which can be obtained by using - the --with-colons options (it is the fifth field in the lines - beginning with "sec"). - -<Q> What are trust, validity and ownertrust? - - "ownertrust" is used instead of "trust" to make clear 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 so introduce) other - keys. "validity", or calculated trust, is a value which says how - much GnuPG thinks a key is valid (that it really belongs to the one - who claims to be the owner of the key). For more see the chapter - "The Web of Trust" in the Manual. - -<Q> 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. - -<Q> 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". - -<Q> 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. - -<Q> What does the "You are using the xxxx character set." mean? - - This note is printed when UTF8 mapping has to be done. Make sure - that the displayed charset is the one you have activated on your - system. Since "iso-8859-1" is the charset 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. - -<Q> How can a get list of key IDs used to encrypt a message? - - [H pre] - gpg --batch --decrypt --list-only --status-fd 1 2>/dev/null | \ - awk '/^\[GNUPG:\] ENC_TO / { print $3 }' - [H /pre] - -<Q> I can't decrypt my symmetrical only (-c) encrypted message with - a new version of GnuPG. - - There used to be a bug in GnuPG < 1.0.1 which happens only if 3DES - or Twofish has been used for symmetric only encryption (this has - never been the default). The bug has been fixed but to enable you - to decrypt old messages, you should run gpg with the option - "--emulate-3des-s2k-bug", decrypt the message and encrypt it again - without this option. The option will be removed in 1.1, so better - re-encrypt your message now. - -<Q> How can I use GnuPG in an automated environment? - - You should use the option --batch and don't use pass phrases as - there is usually no way to store it more secure than the secret - keyring itself. The suggested way to create the keys for the - automated environment is: - - On a secure machine: - [H OL] - [H LI] If you want to do automatic signing, create a signing - subkey for your key (edit menu, choose "addkey" and the DSA). - [H LI] Make sure that you use a passphrase (needed by the current - implementation). - [H LI] gpg --export-secret-subkeys --no-comment foo >secring.auto - [H LI] Copy secring.auto and the public keyring to a test directory. - [H LI] Change to this directory. - [H LI] gpg --homedir . --edit foo and use "passwd" to remove the - passphrase from the subkeys. You may also want to remove all - unused subkeys. - [H LI] Copy secring.auto to a floppy and carry it to the target box. - [H /OL] - - On the target machine: - [H OL] - [H LI] Install secring.auto as secret keyring. - [H LI] Now you can start your new service. It is a good idea to - install some 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. - [H /OL] - -<Q> 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 (MUA) support GnuPG at - varying degrees. Simplifying a bit, there are two ways mail can be - encrypted with GnuPG: the "old style" ASCII armor, i.e. plain text - encryption, and RFC2015 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. - - The following list is probably not exhaustive: - - OpenPGP: Mutt (Unix), Emacs/Mew, Becky2 (Windows, with plugin), - TkRat (Unix). There is effort for a Mozilla plugin and - Emacs/GNUS has support in the current CVS. - - ASCII: Emacs/{VM,GNUS}/MailCrypt, Mutt(Unix), Pine(Unix), and - probably many more. - - Good overviews of OpenPGP-support can be found at - [H a href=http://cryptorights.org/pgp-users/pgp-mail-clients.html]http://cryptorights.org/pgp-users/pgp-mail-clients.html[H /a] - and [H a href=http://www.geocities.com/openpgp/courrier_en.html]http://www.geocities.com/openpgp/courrier_en.html[H /a]. - -<Q> 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 [H a href=ftp://ftp.guug.de/pub/gcrypt/alpha/gpgme]ftp://ftp.guug.de/pub/gcrypt/alpha/gpgme[H /a]. - -<Q> 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: - - [H pre] - gpg --import my-revocation.asc - [H /pre] - - then send the revoked key to the keyservers: - - [H pre] - gpg --keyserver certserver.pgp.com --send-keys mykeyid - [H /pre] - - (or use a keyserver web interface for this). - -<Q> 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: - - [H pre] - --homedir /my/path/ - [H /pre] - - 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. - - -<S> COMPATIBILITY ISSUES - -<Dcompat> -<Q> How can I encrypt a message with GnuPG so that PGP is able to decrypt it? - - It depends on the PGP version. - - [H UL] - [H LI]PGP 2.x[H br] - You can't do that because PGP 2.x normally uses IDEA which is not - supported by GnuPG as it is patented (see <Ridea>), but if you have a - modified version of PGP you can try this: - - [H pre] - gpg --rfc1991 --cipher-algo 3des ... - [H/pre] - - 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. - - [H LI]PGP 5.x and higher[H br] - You need to provide two additional options: - - [H pre] - --compress-algo 1 --cipher-algo cast5 - [H/pre] - - 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: - - [H pre] - compress-algo 1 - [H/pre] - - into your ~/.gnupg/options file - this does not affect normal GnuPG - operation. - - This applies to conventional encryption as well. - [H /UL] - -<Q> 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 - <Ridea> about how to add IDEA support to GnuPG and read - [H a href=http://www.gnupg.org/gph/en/pgp2x.html]http://www.gnupg.org/gph/en/pgp2x.html[H /a] to perform the migration. - -<Q> (removed) - - (empty) - -<Q> 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. - -<Q> 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. - -<Q> 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: - - [H pre] - $ lspgpot pgpkeyring | gpg --import-ownertrust - [H /pre] - - where pgpkeyring is the original keyring and not the GnuPG keyring - you might have created in the first step. - -<Q> 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: - - [H pre] - $ gpg --export-secret-keys --no-comment -a your-key-id - [H /pre] - - 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: - - [H pre] - $ gpg --s2k-cipher-algo=CAST5 --s2k-digest-algo=SHA1 \ - --compress-algo=1 --edit-key <username> - [H /pre] - - 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: - - [H pre] - $ gpg --s2k-cipher-algo 3des --compress-algo 1 --rfc1991 \ - --export-secret-keys <key-ID> - [H /pre] - - -<S> PROBLEMS and ERROR MESSAGES - -<Q> 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. - - On UnixWare 2.x and 7.x you should install GnuPG with the 'plock' - privilege to get the same effect: - - [H pre] - filepriv -f plock /path/to/gpg - [H /pre] - - If you can't or don't want to install GnuPG setuid(root), you can - use the option "--no-secmem-warning" or put: - - [H pre] - no-secmem-warning - [H /pre] - - in your ~/.gnupg/options 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: - - [H pre] - gpg: Please note that you don't have secure memory - [H /pre] - - 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. - -<Q> Large File Support doesn't work ... - - LFS is correctly working in post-1.0.4 CVS. If configure doesn't - detect it correctly, 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. - -<Q> In the edit menu the trust values is 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. - -<Q> 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. - -<Q> GnuPG 1.0.4 doesn't create ~/.gnupg ... - - That's a known bug, already fixed in newer versions. - -<Q> An ElGamal signature does not verify anymore since version 1.0.2 ... - - Use the option --emulate-md-encode-bug. - -<Q> Old versions of GnuPG can't verify ElGamal signatures - - Update to GnuPG 1.0.2 or newer. - -<Q> 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. - -<Q> 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. - -<Q> 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. - -<Q> I get "gpg: waiting for lock ..." - - A previous gpg has most likely exited abnormally and left a lock - file. Go to ~/.gnupg and look for .*.lock files and remove them. - -<Q> Older gpg's (e.g., 1.0) have problems with keys from newer gpgs ... - - 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's have problems with newer - keys. Because of security 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: - - [H pre] - cipher-algo cast5 - [H /pre] - - into your options file. - -<Q> 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. - -<Q> 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. - -<Q> 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 - [H a href=http://bugs.guug.de/Reporting.html]http://bugs.guug.de/Reporting.html[H /a]. - -<Q> Why doesn't GnuPG support X509 certificates? - - GnuPG, first and foremost, is an implementation of the OpenPGP - standard (RFC 2440), which is a competing infrastructure, different - from X509. - - They are both public-key cryptosystems, but how the public keys are - actually handled is different. - -<Q> 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. - -<Q> 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 a: - - [H pre] - unset CDPATH - [H /pre] - - statement below it. - -<Q> 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: - - [H pre] - http://www.gnupg.org/developer/gpg-woody-fix.txt - [H /pre] - - -<S> ADVANCED TOPICS - -<Q> How does this whole thing work? - - To generate a secret/public keypair, run: - - [H pre] - gpg --gen-key - [H/pre] - - 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. Things 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: - - [H pre] - gpg --fingerprint user-id - [H/pre] - - 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. - -<Q> 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. - -<Q> 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. - - [H pre] - gpg --list-keys --with-colons - [H/pre] - - If the first field is "pub" or "uid", the second field shows you the - trust: - - [H pre] - 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 - [H/pre] - - 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: - - [H pre] - gpg --list-ownertrust - [H/pre] - - The first field is the fingerprint of the primary key, the second - field is the assigned value: - - [H pre] - - = No Ownertrust value yet assigned. - 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. - [H/pre] - - 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). - -<Q> 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. - -<Q> 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. - - [H pre] - "key 12345678.3456" - [H/pre] - - 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. - - [H pre] - "uid 12345678.3456/ACDE" - [H/pre] - - 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. - - [H pre] - "sig 12345678.3456/ACDE/9A8B7C6D" - [H/pre] - - 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 (..//..). - -<Q> 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. - -<Q> 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. - -<Q> 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. - - -<S> ACKNOWLEDGEMENTS - - Many thanks to Nils Ellmenreich for maintaining this FAQ file for - 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). - -[H HR] - -Copyright (C) 2000-2002 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. |