diff options
Diffstat (limited to '')
| -rw-r--r-- | doc/FAQ | 166 |
1 files changed, 81 insertions, 85 deletions
@@ -23,11 +23,10 @@ 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. + 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 @@ -63,12 +62,12 @@ 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. + 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 + 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). @@ -94,31 +93,31 @@ a v3 packet. GNUPG is the only program which had used these v3 ElGamal keys - so this assumption is quite safe. - Q: Why is PGP 5.x not able to encrypt messages with my public key. + Q: Why is PGP 5.x not able to encrypt messages with my public key? A: PGP Inc refuses to accept ElGamal keys of type 20 even for encryption. They only supports type 16 (which are identical - at least for decryption). To be better interoperable, GNUPG + 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 an 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. + Q: Why is PGP 5.x not able to verify my messages? A: PGP 5.x does not accept V4 signatures for data material but OpenPGP requires generation of V3 signatures for all kind of data. Use the option "--force-v3-sigs" to generate V3 signatures for data. Q: I can't delete an user id because it is already deleted on my - public keyring. + public keyring? A: Because you can only select from the public key ring, there is - no direct way to do this. However it is not so complicated - do to it anyway: Create a new user id with exactly the same name, - you will notice that there are two identical user ids on the - secret ring now. Now select this user id and delete it; both - user ids from the secret ring will be removed. + no direct way to do this. However it is not very complicated + to do it 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: How can I encrypt a message in way pgp 2.x is able to decrypt it later? + Q: How can I encrypt a message so that pgp 2.x is able to decrypt it? A: You can't do that because pgp 2.x normally uses IDEA which is not supported by GNUPG because it is patented, but if you have a modified version of PGP you can try this: @@ -130,11 +129,11 @@ gpg -c --cipher-algo 3des --compress-algo 1 --no-comment myfile - You may replace "3des" by "cast5"; "blowfish" does not work with + You may replace "3des" by "cast5". "blowfish" does not work with all versions of pgp5. You may also want to put no-comment compress-algo 1 - into your ~/.gnupg/options file - this does not affect the normal + into your ~/.gnupg/options file - this does not affect normal gnupg operation. @@ -142,42 +141,40 @@ A: 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 commited that the best way to fill the - buffer is to play with your keyboard. - Good security has it's price. - What I do is to hit several times on the shift,control, alternate, - capslock keys, as these keys do not produce any output to the screen. - This way you get your keys really fast (it's the same thing pgp2 does). + 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 it's price. What I do + is to hit several times on the shift, control, alternate, and capslock + 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/[u]random). Q: And it really takes long when I work on a remote system. Why? - A: 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 keyring (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, your secret key and trust your Root. + A: 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 keyring (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 trust your Root. When I check gnupg on a remote system via ssh (I have no Alpha here ;-) - I have the same problem too: it takes *very* long to create the keys, - so I use a special option --quick-random to generate insecure keys which are - only good for some tests. + 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: How does the whole trust thing work? - A: 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 + A: 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. I have plans to use a cache for calculated trust values to speed up calculation. - You can see the validity (calculated trust value) using this command: + You can see the validity (calculated trust value) using this command. gpgm --list-keys --with-colons @@ -193,13 +190,13 @@ is only used for keys for which the secret key is also available. - You can get a list of the assigned trust values (how far you trust - the owner to correctly sign another one's key) + You can get a list of the assigned trust values (how much you trust + the owner to correctly sign another person's key) gpgm --list-ownertrust - The first field is the fingerprint of the primary key, the second one - the assigned value: + The first field is the fingerprint of the primary key, the second field + is the assigned value: - = No Ownertrust value yet assigned. n = Never trust this keyholder to correctly verify others signatures. @@ -207,42 +204,42 @@ f = Assume that the key holder really knows how to sign keys. u = No need to trust ourself because we have the secret key. - Please keep these values confidential, as they express some opinions of - you about others. PGP does store these information with the keyring, so - it is not a good idea to publish the keyring instead of exporting the - keyring - gnupg stores the trust in the trust-DB and therefor it is okay - to give the keyring away (but we have a --export command too). + 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 trust-DB so it is okay + to give a gpg keyring away (but we have a --export command too). Q: What is the difference between options and commands? - A: 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: + A: 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 -o) is an option which takes a filename. The option's argument - must follow immediately after the option itself: otherwise gpg doesn't know + 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 --remote-user (-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: + argument. The --encrypt (or -e) command comes after all the options followed + by the file you wish to encrypt. So use gpg -r alice -o secret.txt -e test.txt - If you write the options out in full, it is easier to read: + If you write the options out in full, it is easier to read gpg --remote-user alice --output secret.txt --encrypt test.txt 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: + ASCII-armored text in there, so you need to add the --armor (-a) option, + which doesn't take any arguments. gpg --armor --remote-user alice --output secret.txt --encrypt test.txt @@ -251,7 +248,7 @@ gpg [--armor] [--remote-user alice] [--output secret.txt] --encrypt test.txt - The optional parts can be rearranged any way you want: + The optional parts can be rearranged any way you want. gpg --output secret.txt --remote-user alice --armor --encrypt test.txt @@ -268,30 +265,30 @@ Q: What kind of output is this: "key C26EE891.298, uid 09FB: ...."? A: This is the internal representation of an user id in the trustdb. "C26EE891" is the keyid, "298" is the local id (a record number - in the trustdb) and "09FB" are the last two bytes of a ripe-md-160 + in the trustdb) and "09FB" is the last two bytes of a ripe-md-160 hash of the user id for this key. Q: What is trust, validity and ownertrust? A: "ownertrust" is used instead of "trust" to make clear that - this is the value you have assigned to key to express, how far you + this is the value you have assigned to 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 far the gnupg thinks a key is valid (that it really belongs + other keys. "validity", or calculated trust, is a value which + says how much the 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 [gpg: Oops: Internal error: manual not found - sorry] - Q: How do interpret some of the informational outputs: - A: While checking the validness of a key, GnuPG sometimes print - some informations which are prefixed with information about - the checked item: + Q: How do interpret some of the informational outputs? + A: 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 + 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" @@ -302,15 +299,14 @@ Q: How do I sign a patch file? A: 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 of lines starting with a dash and these are - then quoted and that is not good for patch ;-). In order 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. + The problem with --clearsign is that all lines starting with a dash are + quoted with "- "; obviously diff produces many of lines starting with a + dash and these are then quoted and that is not good for 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. |