Sign encrypted mails.

- Husk now not only encrypts outgoing emails (if possible) but also adds
  a signature.
- Rework the internal handling of the signing key.
- Integrate the signing into the workflow of the daemon.
- Add a configuration option for a subject replacement.

e2e-tests/common.sh

@@ -18,7 +18,7 @@ send_test_mail() { # email_address
   chown $USER:mail /var/mail/$USER
   chmod 600 /var/mail/$USER
 
-  echo "test mail" | sendmail $1
+  echo -e "Subject: testmail\n\ntest mail" | sendmail $1
   inotifywait -qq -t 3 -e close_write /var/mail/$USER
 }
 

e2e-tests/tests/60_signing.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/bash
+
+# source some functions
+. common.sh
+
+test_header "Signing"
+
+# sq key generate --shared-key --without-password --email 'signing@example.com' --output /tmp/signing.pgp --rev-cert /tmp/signing.rev
+
+SIGN_FPR=$(sq key generate --own-key --without-password --name "Signing Key" 2>&1 | grep "Fingerprint:" | cut -d ':' -f 2)
+
+cd $HUSK_DIR
+
+$HUSK_BIN --config config/config.toml signkey set --cert $SIGN_FPR
+SIGN_FPR=$($HUSK_BIN --config config/config.toml signkey show | cut -d ':' -f 2 | tr -d ' ')
+echo "found signing key $SIGN_FPR"
+
+create_unix_user juliette
+JULIETTE_FPR=$(sq key generate --own-key --without-password --name "Juliette" --email "juliette@example.com" 2>&1 | grep "Fingerprint:" | cut -d ':' -f 2)
+sq pki vouch add --certifier-userid "CA" --cert $JULIETTE_FPR --all > /dev/null 2>&1
+
+# send a mail, husk should encrypt it
+echo "send mail to juliette@example.com"
+send_test_mail juliette@example.com
+
+if [ -f /var/mail/juliette ] ; then
+  if grep -q "BEGIN PGP MESSAGE" /var/mail/juliette ; then
+
+    FOUND_FPR=$(sq packet dump /var/mail/juliette | grep "Issuer Fingerprint:" | cut -d ':' -f 2 | tr -d ' ')
+
+    if [ "$SIGN_FPR" != "$FOUND_FPR" ] ; then
+      echo "Found wrong fingerprint '$FOUND_FPR' - expected '$SIGN_FPR'"
+      RESULT_CODE=1
+    else
+      RESULT_CODE=0
+    fi
+  else
+    echo "no encryption detected"
+    exit 1
+  fi
+else
+  echo "no mail detected"
+  exit 1
+fi
+