Using GnuPG with Mutt

Hello all, well first of all I am writing this post for a couple of reasons. In the fact for three reasons.
  1. I believe that everyone should be using encryption and signatures in their email and I believe that if you
    are already using a mail client such as Mutt (which a few of people are), then there is absolutely no reason
    for you not to be using PGP-compatible software. :)

  2. all of the documentation that I've seen thus far is geared toward someone who is already familiar with PGP,
    so it just explains things like how to configure Mutt to do such tasks as automatically sign outgoing messages
    or write a procmail recipe to rewrite old-style inline PGP messages as S/MIME messages.

  3. I enjoy writing posts, especially that this is my 1st post and I hope that this one is of use to many people. I did a lot of research
    and I figured a number of things out on my own, and now I want to help people along.

OK, so before I write any further lines, I assume that you know already Mutt and you know how to configure GnuPG, protecting your private key
and how you publish your public key and many other things like why you need to sign your send-mail, and how they are made, etc..
Well, if you don't know those, you need to duckduck it, and if you didn't have a complete understanding of all those things and more, mail me
and I will answer about any questions and why not writing another post about those things.

If you still here, then I think you know what I was talking about, so let's begin! :D

In order to use Mutt with GnuPG, PGP support must be compiled in when building Mutt (this happens by default).
Also, you need to add some directives to your .muttrc (or source a file containing these directives) which tells Mutt how to interact with GnuPG.
Here are the commands that everyone use:

set pgp_decode_command="gpg %?p?--passphrase-fd 0? --no-verbose --batch --output - %f"
set pgp_verify_command="gpg --no-verbose --batch --output - --verify %s %f"
set pgp_decrypt_command="gpg --passphrase-fd 0 --no-verbose --batch --output - %f"
set pgp_sign_command="gpg --no-verbose --batch --output - --passphrase-fd 0 --armor --detach-sign --textmode %?a?-u %a? %f"
set pgp_clearsign_command="gpg --no-verbose --batch --output - --passphrase-fd 0 --armor --textmode --clearsign %?a?-u %a? %f"
set pgp_encrypt_only_command="pgpewrap gpg --batch --quiet --no-verbose --output - --encrypt --textmode --armor --always-trust --encrypt-to 0x71f3c5ce -- -r %r -- %f"
set pgp_encrypt_sign_command="pgpewrap gpg --passphrase-fd 0 --batch --quiet --no-verbose --textmode --output - --encrypt --sign %?a?-u %a? --armor --always-trust --encrypt-to 0x71f3c5ce -- -r %r -- %f"
set pgp_import_command="gpg --no-verbose --import -v %f"
set pgp_export_command="gpg --no-verbose --export --armor %r"
set pgp_verify_key_command="gpg --no-verbose --batch --fingerprint --check-sigs %r"
set pgp_list_pubring_command="gpg --no-verbose --batch --with-colons --list-keys %r"
set pgp_list_secring_command="gpg --no-verbose --batch --with-colons --list-secret-keys %r"
set pgp_autosign=yes
set pgp_sign_as=0x71f3c5ce
set pgp_replyencrypt=yes
set pgp_timeout=1800
set pgp_good_sign="^gpg: Good signature from"

And this is my repo on github contains all the content of the folder .mutt/ that I use.

Aside from the basic commands necessary to inter-operate with GnuPG, these directives also tell Mutt to automatically sign all outgoing
messages using key ID 0x71f3c5ce (my key), to encrypt all encrypted mail to me as well (for storage in my 'sent' folder, and to cache my
passphrase for a half hour.
So, what you need to do know is trying it all out \o/
Mutt should be ready to go at this point. The first time you send a message, Mutt will ask you for your passphrase, which it will then
cache, then it will sign all outgoing messages. When you receive a signed message, Mutt will use the sender's public key (fetching it if it
has to) to verify the signature. When encrypting messages, it will ask for your passphrase (if not cached) and will present you with a menu of
public keys that it believes match the intended recipient. Lastly, when decrypting messages, it will ask you for your passphrase if the cache
has expired or it hasn't been entered yet.