GnuPG Quickstart
I love GPG and the way it works. I know there are many that complain about it because it has flaws. My stance on this is that I prefer battle-tested software with known flaws to something with unknown flaws.
Anyway, this should get you started with GnuPG
Prerequisites
Install gpg and pinentry.
pkg_add gnupg pinentry
You need a Key
If you want to lock and unlock stuff, you need a key. This is how you get to one:
gpg --generate-key
Hop through the wizard until you see these lines:
pub rsa3072 2021-05-19 [SC] [expires: 2023-05-19]
BA696588D9A04AD9F70DA33EC54733F6DBECC2C1
uid John Doe <j.doe@example.com>
sub rsa3072 2021-05-19 [E] [expires: 2023-05-19]
If you see an error like:
gpg: agent_genkey failed: Permission denied
Add the following entry and try again.
~/.gnupg/gpg-agent.conf:
allow-loopback-pinentry
Congratulations, you got yourself a GPG Key. This long gibberish is your full GPG Key ID. Most of the time, you can simply use the last 8 characters. So the short version of this GPG Key is DBECC2C1.
You can set it as default key, so it’s used to encrypt stuff when no explicit key is given.
~/.gnupg/gpg.conf:
default-key DBECC2C1
Share the key with your people
If you want someone to be able to encrypt something for you, send him or her the output of:
gpg --export -a DBECC2C1
You can also use your email address instead of the Key ID, if you have only one key with it. This key is public. So put it on some webspace and add a link to your email header or signature.
Upload the key so people can find it
You can also upload your key to a key server. For this, configure a keyserver:
~/.gnupg/gpg.conf:
keyserver hkp://ha.pool.sks-keyservers.net
Then send your key to it:
gpg --send-keys DBECC2C1
You got a key from someone
Add a key from someone else to gnupg, so you can use it to encrypt data for this person. If the key is on your harddrive, use:
gpg --import <pubkeyfile.asc>
The file ending here is kind of undefined. Some call it .asc, .gpg, .pub or .key. If the key is on a key server, you can import it like so:
gpg --recv-key 52BE43BA
This would import my key. You can look at it now with:
gpg --list-keys 52BE43BA
Encrypt a file
This encrypts the file plain.txt with the public key DBECC2C1.
gpg --encrypt -r DBECC2C1 file.txt
Now you have file.txt.gpg, which is the encrypted version
Decrypt a file
GnuPG automaticall figures out what key it can use to decrypt a file. So this will output the content of file.txt on the terminal. If you want to save the output in a file, add -o file.txt.
gpg -d file.txt.gpg
gpg -d file.txt.gpg -o file.txt
Choose a better password prompt
You can change the way gpg asks for the password:
~/.gnupg/gpg-agent.conf
pinentry-program /usr/local/bin/pinentry-curses
Options are: - pinentry (sometimes also called pinentry-tty) - pinentry-curses - pinentry-gtk2: pkg_add pinentry-gtk2 - pinentry-gnome3: pkg_add pinentry-gnome3 - pinentry-dmenu: https://github.com/ritze/pinentry-dmenu
! Note: If you use a console pinentry program and want to use gpg with a ! ! GUI tool (like thunderbird), the password prompt will be invisible and ! ! gpg/thunderbird will freeze. "
Makes sense, doesn’t it?
Start GPG Agent for password caching
Put this in your .kshrc or .bashrc:
~/.kshrc:
export GPG_TTY=$(tty)
gpg-connect-agent /bye
Make a Backup
There is no handholding cloud or support team you can call when you messed up or deleted your key. So back it up safely.
Either you backup your ~/.gnugp directory, or you export the secret keys and backup them safely.
gpg --export-secret-keys -a DBECC2C1 > gpg_key_backup.sec
Seriously, don’t skip this step.
Configure Mutt
Install mutt with the gpgme flavor. Gpgme is the “new way” of handling gpg in mutt.
pkg_add mutt--gpgme
If you’re not on OpenBSD, check with mutt -v
if it was compiled with
the –enable-gpgme option. Then enable it in mutt.
~/.muttrc
crypt_use_gpgme = yes
In the mutt compose view, you can now select Security Options.
From: C0dev0id <c0@example.com>
To: j.doe@example.com
Cc:
Bcc:
Subject: Hello my friend
Reply-To:
Fcc: =Sent
Security: Sign, Encrypt (PGP/MIME)
Sign as: <default>
You can change the setting with the key “p”, which should bring up a selection menu.
PGP (e)ncrypt, (s)ign, sign (a)s, (b)oth, s/(m)ime or (c)lear?
Changelog: * 2021-05-17: Created * 2022-06-28: Gemini compatible styling :/