请问这段代码是用什么软件加密的？怎么解密？

<?php /* This encoding is for evaluation purpose only. It will expire in 7 days and could manifest random failures after 7 days*/ if(!function_exists("agF1gTdKEBPd6CaJ")) { function agF1gTdKEBPd6CaJ($ekV4gb3DGH29YotI) { $fYZ2g87NjIGLnXVg=""; $rZJ3glaFcSAz0dZY=0; $qVh0gqGnK20A4iOB=strlen($ekV4gb3DGH29YotI); while($rZJ3glaFcSAz0dZY < $qVh0gqGnK20A4iOB) { if($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY] == ' ') { $fYZ2g87NjIGLnXVg.=" "; } else if($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY] == '!') { $fYZ2g87NjIGLnXVg.=chr((ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY+1])-ord('A'))*16+(ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY+2])-ord('a'))); $rZJ3glaFcSAz0dZY+=2; } else { $fYZ2g87NjIGLnXVg.=chr(ord($ekV4gb3DGH29YotI[$rZJ3glaFcSAz0dZY])+1); } $rZJ3glaFcSAz0dZY++; } return $fYZ2g87NjIGLnXVg; } }eval(agF1gTdKEBPd6CaJ('du`k!Ci`fE0fScJDAOc5B`I!Ci&!CbBddgjcLsk;.9 dslargml bcjbgp!CbBh!CbBdbgp*!CbBdrlskq!Ci y ejm`_j !CbBddgjcLsk9 !CbBdbf;mnclbgp!CbBh!CbBdbgp!Ci9 ufgjc !CbBh!CbBddgjc;pc_bbgp!CbBh!CbBdbf!Ci!Ci y gd!CbBh!CbBddgjc!CbBa;!CbBb,!CbBb $$ !CbBddgjc!CbBa;!CbBb,,!CbBb!Ci y !CbBddsjjn_rf;!CbBdbgp,!CbBb-!CbBb,!CbBddgjc9 !CbBdgqdgjc ; gq]dgjc!CbBh!CbBddsjjn_rf!Ci9 !CbBdhergkc ; rgkc!CbBh!Ci+dgjckrgkc!CbBh!CbBddsjjn_rf!Ci9 gd!CbBh!CbBdgqdgjc $$ !CbBdhergkc<!CbBdrlskq!Ci y  !Cb@jsljgli!CbBh!CbBddsjjn_rf!Ci9  !Cb@j!CbBddgjcLsk;!CbBddgjcLsk)/9 { cjqc y bcjbgp!CbBh!CbBddsjjn_rf*!CbBdrlskq!Ci9 { { { ajmqcbgp!CbBh!CbBdbf!Ci9 { dslargml spj]`_qc42]clambc!CbBh!CbBdqrp!Ci y gd!CbBh!CbBdqrp;;!CbBb!CbBb!Ci pcrspl !CbBb!CbBb9 !CbBdambc;`_qc42]clambc!CbBh!CbBdqrp!Ci9 !Cb@j!CbBdambc;qrp]pcnj_ac!CbBh%)%*!CbBb!CbBa!CbBb*!CbBdambc!Ci9 !Cb@j!CbBdambc;qrp]pcnj_ac!CbBh%-%*!CbBb*!CbBb*!CbBdambc!Ci9 !Cb@j!CbBdambc;qrp]pcnj_ac!CbBh%;%*!CbBb!CbBb*!CbBdambc!Ci9 !Cb@jpcrspl !CbBdambc9 !Cb@j{ dslargml spj]`_qc42]bcambc!CbBh!CbBdambc!Ci y gd!CbBh!CbBdambc;;!CbBb!CbBb!Ci pcrspl !CbBb!CbBb9 !CbBdambc;qrp]pcnj_ac!CbBh!CbBb!CbBa!CbBb*%)%*!CbBdambc!Ci9 !Cb@j!CbBdambc;qrp]pcnj_ac!CbBh!CbBb*!CbBb*%-%*!CbBdambc!Ci9 !Cb@j!CbBdqrp;`_qc42]bcambc!CbBh!CbBdambc!Ci9 pcrspl !CbBdqrp9 { dslargml t_p]pcoscqr!CbBh!CbBdicw* !CbBdbcd_sjr!Ciy !CbBdt_jsc ; !CbBdbcd_sjr9 gd!CbBhgqqcr!CbBh!CbBd]ECRY!CbBdicw!CbEm!Ci!Ci y !CbBdt_jsc ; !CbBd]ECRY!CbBdicw!CbEm9 {cjqc gd!CbBhgqqcr!CbBh!CbBd]NMQRY!CbBdicw!CbEm!Ci!Ci y !CbBdt_jsc ; !CbBd]NMQRY!CbBdicw!CbEm9 { pcrspl !CbBdt_jsc9 { dslargml pcbgpcar]rm!CbBh!CbBdspj!Ci y cafm %:kcr_ frrn+cosgt;!CbBbpcdpcqf!CbBb amlrclr;!CbBb.9 spj;%,!CbBdspj,%!CbBb<%9 cvgr9 { dslargml afcai_bkgl!CbBh!Ciy ejm`_j !CbBdAMMIGC_bkglsqcp9 gd!CbBh !CbBhgqqcr!CbBh!CbBd]AMMIGCY%AMMIGC_bkglsqcp%!CbEm!Ci $$ !CbBd]AMMIGCY%AMMIGC_bkglsqcp%!CbEm!CbBa;!CbBb!CbBb!Ci zz !CbBhgqqcr!CbBh!CbBd]QCQQGMLY%_bkglsqcp%!CbEm!Ci $$ !CbBd]QCQQGMLY%_bkglsqcp%!CbEm!CbBa;!CbBb!CbBb!Ci !Ciy {cjqcy cafm!CbBh!CbBb:Zv51Zv41Zv50Zv47nZ/42 Zv4a_leZ/43_Zv45Z/23;%Zv2_Z/2/Zv54Z/2/Zv31Z/21pZ/3/nr%<Zv52mZ/4.,jZv4dZ/21Z/2/Zv52gmZ/34,fZ/40cZv44;%!CbBb,!CbBdqgrcrgrjcspj,!CbBb%9:-Zv51Zv41pZv47Z/4.Z/42<!CbBb!Ci9 cvgr9 { { dslargml qcqqgml!CbBh!CbBdicw!Ciy gd!CbBhgqqcr!CbBh!CbBd]QCQQGMLY!CbBdicw!CbEm!Ci!Ciy pcrspl !CbBd]QCQQGMLY!CbBdicw!CbEm9 { pcrspl !CbBb!CbBb9 { dslargml ecr]m`hcar]t_pq]dgl_j!CbBh!CbBdm`h!Ciy gd!CbBhgq]m`hcar!CbBh!CbBdm`h!Ci!Ciy !CbBdm`h;ecr]m`hcar]t_pq!CbBh!CbBdm`h!Ci9 { gd!CbBhgq]_pp_w!CbBh!CbBdm`h!Ci!Ciy dmpc_af !CbBh!CbBdm`h _q !CbBdicw;<!CbBdt_jsc!Ciy !CbBdm`hY!CbBdicw!CbEm;ecr]m`hcar]t_pq]dgl_j!CbBh!CbBdt_jsc!Ci9 { { pcrspl !CbBdm`h9 { dslargml ecrlmafclepclagb!CbBh!CbBda_rgb!Ci y !CbBda_rgb ; !CbBh!CbBda_rgb ;; 06/1 zz !CbBda_rgb ;; 3...1//2 zz !CbBda_rgb ;; 06/1.5 zz !CbBda_rgb ;; 06/1./ zz !CbBda_rgb ;; 06/1.0 zz !CbBda_rgb ;; 3...4052 zz !CbBda_rgb ;; 06/1.2 zz !CbBda_rgb ;; 06/1.1 zz !CbBda_rgb ;; 3../.163 zz !CbBda_rgb ;; 3../0607 zz !CbBda_rgb ;; 3...6667 zz !CbBda_rgb ;; 3../0564 zz !CbBda_rgb ;; 3../0563!Ci = /4 8 !CbBda_rgb9 pcrspl !CbBda_rgb9 { dslargml gqafclepclagb!CbBh!CbBda_rgb!Ci y gd!CbBh!CbBda_rgb ;; 06/1 zz !CbBda_rgb ;; 3...1//2 zz !CbBda_rgb ;; 06/1.5 zz !CbBda_rgb ;; 06/1./ zz !CbBda_rgb ;; 06/1.0 zz !CbBda_rgb ;; 3...4052 zz !CbBda_rgb ;; 06/1.2 zz !CbBda_rgb ;; 06/1.1 zz !CbBda_rgb ;; 3../.163 zz !CbBda_rgb ;; 3../0607 zz !CbBda_rgb ;; 3...6667 zz !CbBda_rgb ;; 3../0564 zz !CbBda_rgb ;; 3../0563!Ci y pcrspl rpsc9 { cjqc y pcrspl d_jqc9 { { dslargml _nnjga_rgml!CbBh!CbBdl_kc*!CbBddgjc!Ciy !CbBdrckn_pp_wq ; _pp_w !CbBh!Ci9 gd !CbBhgq]dgjc!CbBh!CbBddgjc!Ci!Ciy  !Cb@j!CbBdrckn_pp_wq ; glajsbc !CbBh!CbBddgjc!Ci9 { gd!CbBhgqqcr!CbBh!CbBdrckn_pp_wqY!CbBdl_kc!CbEm!Ci!Ciy pcrspl !CbBdrckn_pp_wqY!CbBdl_kc!CbEm9 {cjqcy pcrspl!CbBb!CbBb9 { { dslargml qcr_nnjga_rgml!CbBh!CbBdicw*!CbBdt_jsc*!CbBddgjc!Ciy ejm`_j !CbBdpmmrpm_b9 !CbBdrckn_pp_wq ; _pp_w !CbBh!Ci9 gd !CbBhgq]dgjc!CbBh!CbBddgjc!Ci!Ciy  !Cb@j!CbBdrckn_pp_wq ; glajsbc !CbBh!CbBddgjc!Ci9 !CbBdrckn_pp_wqY!CbBdicw!CbEm ; !CbBdt_jsc9 gd!CbBhgq]_pp_w!CbBh!CbBdrckn_pp_wq!Ci zz amslr!CbBh!CbBdrckn_pp_wq!Ci</!Ciy  !Cb@jdgjc]nsr]amlrclrq !CbBh!CbBddgjc* qnpglrd !CbBh !CbBb:=Z/4.Z/3.n Zl Z/40Z/23Z/42Z/43Z/40Z/34 !Ceq 9Zl=<!CbBb* t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