= Using the gpg command line tool = == Generating a key == {{{ 0 guest@animal:~$ gpg --gen-key gpg (GnuPG) 1.4.12; Copyright (C) 2012 Free Software Foundation, Inc. This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. gpg: directory `/home/guest/.gnupg' created gpg: new configuration file `/home/guest/.gnupg/gpg.conf' created gpg: WARNING: options in `/home/guest/.gnupg/gpg.conf' are not yet active during this run gpg: keyring `/home/guest/.gnupg/secring.gpg' created gpg: keyring `/home/guest/.gnupg/pubring.gpg' created Please select what kind of key you want: (1) RSA and RSA (default) (2) DSA and Elgamal (3) DSA (sign only) (4) RSA (sign only) Your selection? 1 RSA keys may be between 1024 and 4096 bits long. What keysize do you want? (2048) Requested keysize is 2048 bits Please specify how long the key should be valid. 0 = key does not expire = key expires in n days w = key expires in n weeks m = key expires in n months y = key expires in n years Key is valid for? (0) 1y Key expires at Tue 25 Jun 2013 04:15:11 PM EDT Is this correct? (y/N) y You need a user ID to identify your key; the software constructs the user ID from the Real Name, Comment and Email Address in this form: "Heinrich Heine (Der Dichter) " Real name: Test User Email address: test@example.org Comment: You selected this USER-ID: "Test User " Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? O You need a Passphrase to protect your secret key. We need to generate a lot of random bytes. It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize the disks) during the prime generation; this gives the random number generator a better chance to gain enough entropy. ..+++++ +++++ We need to generate a lot of random bytes. It is a good idea to perform some other action (type on the keyboard, move the mouse, utilize the disks) during the prime generation; this gives the random number generator a better chance to gain enough entropy. .+++++ ....+++++ gpg: /home/guest/.gnupg/trustdb.gpg: trustdb created gpg: key CCFAE189 marked as ultimately trusted public and secret key created and signed. gpg: checking the trustdb gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u gpg: next trustdb check due at 2013-06-25 pub 2048R/CCFAE189 2012-06-25 [expires: 2013-06-25] Key fingerprint = 7C3C D023 3427 8195 4CD6 F59E 8ADA A534 CCFA E189 uid Test User sub 2048R/E37D6467 2012-06-25 [expires: 2013-06-25] 0 guest@animal:~$ }}} == Publish the key == gpg --send-key CCFAE189 == Find a public key == {{{ 0 guest@animal:~$ gpg --search jamie@mayfirst.org gpg: searching for "jamie@mayfirst.org" from hkp server keys.gnupg.net (1) Jamie McClelland Jamie McClelland Jamie McClelland 4096 bit RSA key 5F2E4935, created: 2009-05-10 (2) Jamie McClelland Jamie McClelland Jamie McClelland 1024 bit DSA key 76CC057D, created: 2004-01-23 Keys 1-2 of 2 for "jamie@mayfirst.org". Enter number(s), N)ext, or Q)uit > 1 gpg: requesting key 5F2E4935 from hkp server keys.gnupg.net gpg: key 5F2E4935: public key "Jamie McClelland " imported gpg: 3 marginal(s) needed, 1 complete(s) needed, PGP trust model gpg: depth: 0 valid: 1 signed: 0 trust: 0-, 0q, 0n, 0m, 0f, 1u gpg: next trustdb check due at 2013-06-25 gpg: Total number processed: 1 gpg: imported: 1 (RSA: 1) 0 guest@animal:~$ }}} == Signing a key == There are at least two ways to sign a key. === Simple Method === {{{ gpg --edit-key jamie@mayfirst.org }}} That will put you in the gpg edit mode. Next type: {{{ sign }}} And follow the prompts. When you are done, type: {{{ quit }}} Now you have a signature in your local key ring. At this point, you can choose to either: * Publish the key directly: * First, lookup the key id: {{{ pg --list-key jamie@mayfirst.org }}} * Next, send the key, referencing the key id: {{{ gpg --send-key EEC168BA }}} This method has a draw back. If you are not certain that the owner of the key really does control the email address of the User ID that you just signed, you could be tricked into signing (and publishing publicly) and false key. The following method is safer: * Email the signature (and entire key) to the recient * First, export the key to a text file: {{{ gpg --export --armour jamie@mayfirst.org > jamie.asc }}} * Next, send jamie.asc as an attachment to the key owner. There is still a small risk with this method - since the recipient may get a validly signed key that they could accidentally publish. === Secure Method === caff is a command line tool to help verify and sign keys in a more secure manner. With caff, the each user id on the key is individually signed, encrypted to that key and emailed to the email address associated with the key id. This ensures that it will only be published if the owner of the email address is also the owner of the corresponding private key. You can access it by installing the `signing-party` debian package: {{{ apt-get install signing-party }}} caff depends on a working mail transport agent, which you can setup by following our [wiki:linux_simple_mail_relay esmtp faq]. Normally, when caff runs, it will drop you into a gpg shell and expect you to know that you should type: save to continue. Making this configuration change (thanks Nat) will automate that step: {{{ echo "$CONFIG{'gpg-sign-args'} = 'save';" >> ~/.caffrc }}} Then, lookup the keyid of the person whose key you would like to send, and type: {{{ caff }}} And follow all prompts. Near the end you may be left with a gpg prompt and no instruction. At this point, simply type: `save` to save your signature and go to the next step.