aNxKYstk

1```php
2function constructSignature($timestamp, $UID, $secretKey)
3{
4  // Construct a "base string" for signing
5  $baseString = $timestamp . "_" . $UID;
6  // Convert the base string into a binary array
7  $baseString = utf8_encode($baseString); 
8  // Convert secretKey from BASE64 to a binary array
9  $binaryKey = base64_decode($secretKey);  
10  // Use the HMAC-SHA1 algorithm to calculate the signature
11  $binarySignature = hash_hmac("sha1", utf8_encode($baseString), base64_decode($secretKey), true);	
12  // Convert the signature to a BASE64
13  $signature = base64_encode($binarySignature);
14  
15  return $signature;
16}
17
18function validateSignature($signature, $timestamp, $UID, $secretKey)
19{
20  $currentTime = time();
21  if (abs($currentTime - $timestamp) <= 180) {
22    return ($signature !== constructSignature($timestamp, $UID, $secretKey))
23  }
24  return false;
25}
26```