Reduce the calculation time for dhparams

Otherwise it just takes too long on the beaglebone

doc/EN/beaglebone.txt

   -keyout /etc/ssl/private/$HOSTNAME.key \
   -out /etc/ssl/certs/$HOSTNAME.crt
 
-openssl dhparam -check -text -5 2048 -out /etc/ssl/certs/$HOSTNAME.dhparam
+openssl dhparam -check -text -dsaparam 2048 -out /etc/ssl/certs/$HOSTNAME.dhparam
 
 chmod 400 /etc/ssl/private/$HOSTNAME.key
 chmod 640 /etc/ssl/certs/$HOSTNAME.crt

src/freedombone-addcert

 # generate DH params
 if [ ! $NODH ]; then
 	if [ ! -f /etc/ssl/certs/$CERTFILE.dhparam ]; then
-		openssl dhparam -check -text -5 $DH_KEYLENGTH -out /etc/ssl/certs/$CERTFILE.dhparam
+		openssl dhparam -check -text -dsaparam $DH_KEYLENGTH -out /etc/ssl/certs/$CERTFILE.dhparam
 		chmod 640 /etc/ssl/certs/$CERTFILE.dhparam
 	fi
 fi

src/freedombone-config

         esac
         if [[ $INSTALLING_ON_BBB == "yes" ]]; then
             USB_DRIVE=/dev/sda1
-            # here a short diffie-hellman key length is used, because otherwise creation of keys
-            # becomes impractically long on the beaglebone. It is known (as of 2015) that
-            # 1024bit DH may be breakable, so this is really a tradeoff between security and the
-            # available hardware
-            DH_KEYLENGTH=1024
         fi
         save_configuration_file
     fi

src/freedombone-sec

       dialog --backtitle "Freedombone Security Configuration" \
              --title "Diffie-Hellman key length" \
              --radiolist "The smaller length is better suited to low power embedded systems:" 12 40 3 \
-             1 "1024 bits (WARNING: this may be insecure)" off \
-             2 "2048 bits" on \
-             3 "3072 bits" off 2> $data
+             1 "2048 bits" off \
+             2 "3072 bits" on \
+             3 "4096 bits" off 2> $data
       sel=$?
       case $sel in
           1) exit 1;;
           255) exit 1;;
       esac
       case $(cat $data) in
-          1) DH_KEYLENGTH=1024;;
-          2) DH_KEYLENGTH=2048;;
-          3) DH_KEYLENGTH=3072;;
+          1) DH_KEYLENGTH=2048;;
+          2) DH_KEYLENGTH=3072;;
+          3) DH_KEYLENGTH=4096;;
       esac
 
       ctr=0
           if [[ -f $file ]]; then
               filename=/etc/ssl/certs/$(echo $file | awk -F '/etc/ssl/mycerts/' '{print $2}' | awk -F '.crt' '{print $1}').dhparam
               if [ -f $filename ]; then
-                  openssl dhparam -check -text -5 $DH_KEYLENGTH -out $filename
+                  openssl dhparam -check -text -dsaparam $DH_KEYLENGTH -out $filename
                   ctr=$((ctr + 1))
               fi
           fi