Added hash_hmac() 256 hashing way.

Author: sudiptpa

src/Message/DirectPostAbstractRequest.php

@@ -33,7 +33,7 @@ public function generateFingerprint(array $data)
 
         $hash = implode('|', $hashable);
 
-        return sha1($hash);
+        return hash_hmac('sha256', $hash, $this->getTransactionPassword());
     }
 
     public function getBaseData()

src/Message/DirectPostCompletePurchaseRequest.php

@@ -31,9 +31,9 @@ public function generateResponseFingerprint($data)
             $data['summarycode'],
         ];
 
-        $fields = implode('|', $hashable);
+        $hash = implode('|', $hashable);
 
-        return sha1($fields);
+        return hash_hmac('sha256', $hash, $this->getTransactionPassword());
     }
 
     public function sendData($data)

src/Message/DirectPostWebhookRequest.php

@@ -22,9 +22,9 @@ public function generateResponseFingerprint($data)
             $data['summarycode'],
         ];
 
-        $fields = implode('|', $hashable);
+        $hash = implode('|', $hashable);
 
-        return sha1($fields);
+        return hash_hmac('sha256', $hash, $data['txn_password']);
     }
 
     public function vefiyFingerPrint($fingerprint)