mutt and S/MIME

                                by

                         Wessel Dankers


Don't even try to use mutt 1.5.9 (e.g. mutt 1.5.9-2 as shipped with Debian
sarge) with S/MIME: such a mutt won't be able to decrypt some valid S/MIME
messages.  Use e.g. (a backport of) 1.5.11-4.


To get Mutt from Debian sarge (1.5.9-2) to deliver some of the needed S/MIME
functionality, I had to coerce it a little.

Two configvars needed changing:

(Debian Bug #315319)

 set smime_encrypt_command="openssl smime -encrypt %a -outform DER -in %f %c"

(or, alternatively, do

 set smime_encrypt_with=des3

)

and:

 set smime_sign_command="openssl smime -sign -signer %c -inkey %k -passin stdin -in %f -outform DER"

Setting up the keys:

% openssl genrsa -out wsl.key 2048
% cat wsl.cfg
[ req ]
default_bits            = 2048
default_keyfile         = wsl.key
distinguished_name      = req_distinguished_name
attributes              = req_attributes
prompt                  = no

[ req_distinguished_name ]
C                       = NL
O                       = Universiteit van Tilburg
OU                      = IT Services
CN                      = Wessel Dankers
emailAddress            = wsl@uvt.nl

[ req_attributes ]
% openssl req -new -newhdr -config wsl.cfg -key wsl.key -days 3650 -sha1 -verify -out wsl.csr

Have this csr signed by your favourite CA. Ours is Fruit CA.
You can create your own CA using the tools in CA/.

Assuming the certificate of Fruit CA is called fruit.crt and ours is called
wsl.crt:

1)  $ smime_keys init
2)  $ smime_keys add_root fruit.crt
   (or equivalent:
    $ cat fruit.crt >~/.smime/ca-bundle.crt
   )
3)  $ smime_keys add_chain wsl.key wsl.crt fruit.crt
   (yes, you have to specify the root ca again!)
4) optionally add a certificate of someone you'd like to communicate with:
    $ smime_keys add_cert joostvb.crt

There's also something fishy going on with its key handling:

cd ~/.smime && for i in */*.0;do ln -sf ${i#*/} ${i%0};done

Now you should be able to send and receive S/MIME signed+encrypted
messages.