Why is the wrong signature VK IFrame formed?

Question

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Good afternoon. I am writing an application for the VK community. I am implementing data authentication and here a problem has surfaced: I am implementing exactly the same code as described here :
I am trying to generate a signature as indicated in the documentation, as a result, with the signature that VK gives, my signature does not match, I twist $ _GET. Tell me what's funny?

$sign = ""; 
$request = $_GET;

foreach ($request as $key => $param) { 
  echo($key."===".$param."<br>");
    if ($key == 'hash' || $key == 'sign') continue; 
    $sign .=$param; 

} 

$secret = '****'; 
$sig = $secret ? hash_hmac('sha256', $sign, $secret) : "";

There was already a similar question , but there was no answer.

Answer 1

Ehh. As usual, as soon as I decided to ask on the network, I found the problem myself. The thing is that the route parameter was added along the way, it spoiled everything.