How to add use mutt's S/MIME capabilities - Add the contents of contrib/smime.rc to your .muttrc. Don't worry about changing the smime_sign_as line at this point -- you'll change it later. - Run 'smime_keys init'. - Download and install OpenSSL. - Get yourself a certificate. (You can get one for free from www.thawte.com, or pay for one from VeriSign or one of its competitors) The way the process generally works, the certificate will be installed "into" your web browser. If you are asked what application you wish to use the certificate with, select Netscape. Strangely enough, "mutt" is usually not an option. - Assuming you are using Mozilla, follow the instructions at www.verisignlabs.com/Projects/smime_docs/linux.html to export the certificate into a file called cert.p12. If you don't use Mozilla, you're on your own. - Run "smime_keys add_p12 cert.p12" * When the script asks for the "Import password", enter the one you provided when you exported the certificate. * When it asks for a "PEM pass phrase", make up a new password. Every time you sign or decrypt a message, mutt will ask for the PEM pass phrase. * Finally, when the script asks for a label, enter an easy-to-remember name for the certificate, such as "me". The script output will include a line like: added private key: /home/raldi/.smime/keys/12345678.0 for raldi@verisignlabs.com The number (including the ".0" at the end) is your keyid. You will need this number in the next step. - Edit the smime_sign_as line in your muttrc, replacing the keyid with your own. - You probably want to import the trusted roots in contrib/ca-bundle.crt. This makes you trust anything that was ultimately signed by one of them. You can use "smime_keys add_root" to do so, or just copy ca-bundle.crt into the place you point mutt's smime_ca_location variable to. Other notes Key management is done in a way similar to OpenSSL's CA directory. Private keys and certificates are stored in different directories, as OpenSSL expects either to be supplied in a (distinct) file. Each directory contains an unsorted file named '.index' wherein each line has several fields: mailbox, keyid, label, id of the intermediate certificate and keyflags. * Keyid is a hashvalue derived from the subject field of a certificate and supplied by OpenSSL. * The mailbox address is derived from either From or Sender field of the message, and matched with the email field of the certificate. Non matching address pairs get rejected, as get certificates not containing a mailbox address at all. (These are security issues, that perhaps should be configurable.) * Label is set by the perl script (it will ask you to supply one), when you add your keypair to the database. So are the remaining two fields. * keyflags are set with certificate verification option of the perl script. It may take as value one of the following: i: invalid (verification failed), r: revoked, e: expired, u: unverified, v: successfully verified and finally t: trusted, in case it was successfully verified and you chose to trust the certificate (the script will ask you). Mutt will not use invalid, revoked or expired certificates for signing or encryption. It will ask for confirmation before using unverified certificates, and finally it will issue a warning before using successfully verified but untrusted certificates. The purpose fields of a certificate do not get verified yet, also there is no real check if the given file is a certificate at all. Key retrieval is done obviously by searching the index file for a given mailbox. If none is found, the user is presented a list of available keys and asked to select one of those. The certificate and key directories specified in muttrc have to exist. Mutt will not create them. If you wish to sign messages yourself, note that this mutt does not address any PKCS10 or PKCS12 issues (yet?); that is, you have to get a valid certificate outside of mutt. (See above) A certificate can be viewed by adding the following to your ~/.mailcap: application/x-pkcs7-signature;openssl pkcs7 -in %s -inform der -noout \ -print_certs -text | less; needsterminal