After Israel dismantled its settlements in Gaza and withdrew ground forces in 2005 in an act of goodwill, Gazans could have reciprocated that goodwill. But they didn't. Hamas ramped up attacks on Israel, so Israel has ramped up the blockade. The blockade is Hamas's fault. All Hamas has to do to get rid of the blockade is credibly commit to not beheading Jewish babies and other evils like that.