Get your own PHP server Result Size: 625 x 565
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<!DOCTYPE html>
<html>
<body>
<?php
$str = "Hello";
echo sha1($str);
if (sha1($str) == "f7ff9e8b7bb2e09b70935a5d785e0cc5d9d0abf0")
  {
  echo "<br>Hello world!";
  exit;
  }
?> 
</body>
</html>
f7ff9e8b7bb2e09b70935a5d785e0cc5d9d0abf0
Hello world!