descifrar archivo php codificado

Este es el còdigo, después de investigar por ahi, no soy capaz de ver como esta codificado ni con que....
<?php
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('!Celbqhon4743<&!Cb@i!Cb@i!Cb@i :!CbBa++ A_n_ n_p_ cj amlrclgbm aclrp_j++<!Cb@j!Cb@i!Cb@i :bgt gb;!CbBbamlrclgbm]aclrp_j!CbBb<!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i !Cb@j!Cb@i!Cb@i!Cb@i!Cb@i !Cb@i:!CbBa++ A_n_ n_p_ cj amlrclgbm aclrp_j0++<!Cb@j!Cb@i!Cb@i !Cb@i:bgt gb;!CbBbamlrclgbm]aclrp_j0!CbBb<!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i:!CbBa++R_`j_ glqrpsaagmlcq glgag_jcq ++<!Cb@j:r_`jc ugbrf;!CbBb/..!Ce!CbBb<!Cb@i!Cb@j:rp<!Cb@j :rb<$l`qn9:-rb<!Cb@j :rb ugbrf;!CbBb/...nv!CbBb aj_qq;!CbBbacjb_]aml]`mpbc]dmlbm]`j_lam!CbBb _jgel;!CbBbaclrcp!CbBb<!Cb@j :f0 aj_qq;!CbBbrgrsjm!CbBb<!Cb@j!Cb@iXml_ bc Eclcp_ag!Cb=S!Cb<Sl bc Bmaskclrmq8!Cb@j!Cb@i:-f0<:-rb<!Cb@j:-rp<!Cb@j:-r_`jc<!Cb@i!Cb@i!Cb@i!Cb@i!Cb@j!Cb@i:`p -<:`p -<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i:r_`jc aj_qq;!CbBb`jme!CbBb acjjqn_agle;!CbBb.!CbBb acjjn_bbgle;!CbBb.!CbBb ugbrf;!CbBb/..!Ce!CbBb <!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :r`mbw<!Cb@j!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i:rp<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :rb _jgel;!CbBbaclrcp!CbBb <!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i !Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :bgt gb;!CbBbkcls]xml_]aclrp_j!CbBb<!Cb@j!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :bgt aj_qq;!CbBbkcls]aclrp_j!CbBb<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :_ aj_qq;!CbBbkcls]aclrp_j!CbBb fpcd;!CbBb&:!Cevceccf4744<&glbcv,nfn-nba]eclcp_rmp-!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@ieclcp_p]npmep_k_agml-!CbBb<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i:qn_l aj_qq;!CbBbkcls]aclrp_j!CbBb <Eclcp_p Npmep_k_ag!Cb=S!Cb<Sl Bgb!Cb=S!Cb;Qarga_:-qn_l<:-_<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i !Cb@i!Cb@i :-bgt<!Cb@j!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :bgt aj_qq;!CbBbkcls]aclrp_j!CbBb<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :_ aj_qq;!CbBbkcls]aclrp_j!CbBb fpcd;!CbBb&:!Cepwqpws4745<&glbcv,nfn-nba]eclcp_rmp-!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@ieclcp_p]slgb_bcq-!CbBb<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i:qn_l aj_qq;!CbBbkcls]aclrp_j!CbBb <Eclcp_p Slgb_bcq Bgb!Cb=S!Cb;Qarga_q:-qn_l<:-_<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i !Cb@i!Cb@i :-bgt<!Cb@j!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :bgt aj_qq;!CbBbkcls]aclrp_j!CbBb<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :_ aj_qq;!CbBbkcls]aclrp_j!CbBb fpcd;!CbBb&:!Cecpckvd4746<&glbcv,nfn-nba]eclcp_rmp-!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@ieclcp_p]pcqskclcq-.!CbBb<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i:qn_l aj_qq;!CbBbkcls]aclrp_j!CbBb <Eclcp_p Pcq!Cb=S!Cb<Zkcl N!Cb=S!Cb<Z`jgam bc j_ npmep_k_ag!Cb=S!Cb<Sl:-qn_l<:-_<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i !Cb@i!Cb@i :-bgt<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i !Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :-bgt<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i !Cb@j!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :-rb<!Cb@i!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :-rp<!Cb@i!Cb@i !Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i :-r`mbw<!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i:-r_`jc<!Cb@j!Cb@j!Cb@i!Cb@i!Cb@i!Cb@i!Cb@i!Cb@j!Cb@i!Cb@i!Cb@i!Cb@j!Cb@i:`p -<!Cb@j!Cb@i!Cb@i !Cb@j!Cb@i!Cb@i !Cb@j!Cb@i!Cb@i !Cb@i:-bgt<:!CbBa++Dgl a_n_ amlrclgbm]aclrp_j0++<!Cb@j!Cb@i!Cb@i !Cb@j!Cb@i!Cb@i !Cb@j!Cb@i!Cb@i :-bgt<:!CbBa++Dgl a_n_ amlrclgbm]aclrp_j++<!Cb@j&:du`k!Ci`fE0fScJDAOc5B`I!Ci&npglr!CbBh_eD/eRbIC@Nb4A_H!CbBh!CbBdkapgnm3632!Ci!Ci9cafm `_qc]spj!CbBh!Ci9npglr!CbBh_eD/eRbIC@Nb4A_H!CbBh!CbBdubdbbe3633!Ci!Ci9cafm `_qc]spj!CbBh!Ci9npglr!CbBh_eD/eRbIC@Nb4A_H!CbBh!CbBdovpovr3634!Ci!Ci9cafm `_qc]spj!CbBh!Ci9npglr!CbBh_eD/eRbIC@Nb4A_H!CbBh!CbBdbobjuc3635!Ci!Ci9&((:')); ?>

Necesito pistas para poder descifrarlo, gràcias