GnuPG Quickstart
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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.
$ cat ~/.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.
$ cat ~/.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:
$ cat ~/.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
tthis will output the content of file.txt on the terminal. If you want
tto 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:
$ cat ~/.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:
$ cat ~/.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
tthe --enable-gpgme option. Then enable it in mutt.
$ cat ~/.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 :/