def to_ssh
      if zero?
        return [0].pack("N")
      else
        buf = to_s(2)
        if buf.getbyte(0)[7] == 1
          return [buf.length + 1, 0, buf].pack("NCA*")
        else
          return [buf.length, buf].pack("NA*")
        end
      end
    end
def to_ssh
      if zero?
        return [0].pack("N")
      else
        buf = to_s(2)
        if buf.getbyte(0)[7] == 1
          return [buf.length + 1, 0, buf].pack("NCA*")
        else
          return [buf.length, buf].pack("NA*")
        end
      end
    end
Converts a BN object to a string. The format used is that which is
 required by the SSH2 protocol.