JERUSALEM — A black market for cigarettes is booming in the besieged Gaza Strip, a window into the lawlessness and desperation in the enclave nine months into Israel’s war against Hamas.

       The illicit cigarettes, one of Gaza’s last forms of currency, are hidden inside hollowed-out watermelons and boxes of diapers, smuggled on trucks through Israeli-controlled crossings and sold for as much as $30 apiece.