# File lib/gpgr.rb, line 105
      def encrypt
        bad_key = @email_addresses.empty?
        
        if File.exists?(@file)
          unless File.readable?(@file)
            raise InvalidFileException.new("File at #{@file} is not readable.") and return
          end
        else
          raise InvalidFileException.new("File at #{@file} does not exist.") and return
        end
        
        @email_addresses.each do |add|
          unless Gpgr::Keys.public_key_installed?(add)
            bad_key = true
          end
        end
        if bad_key
          raise InvalidEmailException.new("One or more of the e-mail addresses you supplied don't have valid keys assigned!")
        else
          command = Gpgr.command + " -q --no-verbose --yes -a -o #{@file_output} -r " + @email_addresses.join(' -r ') + " -e #{@file}"
          system(command)
        end
      end