[sc-7785] Add webhook signature helpers & tests

composer.json

@@ -17,7 +17,8 @@
     "php": ">= 5.6",
     "guzzlehttp/guzzle": ">=6.5",
     "ircmaxell/random-lib": "^1.2",
-    "caseyamcl/guzzle_retry_middleware": "^2.2"
+    "caseyamcl/guzzle_retry_middleware": "^2.2",
+    "tuupola/base62": ">= 1.0"
   },
   "require-dev": {
     "phpunit/phpunit": ">= 5.7",

src/Api.php

@@ -19,6 +19,7 @@
 
 use Smartpay\Responses\Base as BaseResponse;
 use Smartpay\Responses\CheckoutSession as CheckoutSessionResponse;
+use Tuupola\Base62;
 
 /**
  * Class Smartpay.
@@ -344,6 +345,22 @@ public function disableToken($params, $idempotencyKey = null)
         );
     }
 
+    /**
+     * Webhook Signature Helpers
+     */
+
+    public function calculateWebhookSignature($data)
+    {
+        $base62 = new Base62(["characters" => 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789']);
+        return hash_hmac('sha256', $data, $base62->decode(Smartpay::getSecretKey()));
+    }
+
+    public function validateWebhookSignature($data, $signature, $signatureTimestamp)
+    {
+        $calculatedSignature = $this->calculateWebhookSignature($signatureTimestamp . '.' . $data);
+        return $signature === $calculatedSignature;
+    }
+
     /**
      * @param $params
      * @return array

tests/ApiTest.php

@@ -43,4 +43,22 @@ public function testGetOrders()
         $api = new Api('sk_test_mock', 'pk_test_mock', $client);
         $this->assertSame([], $api->getOrders()->asJson());
     }
+
+    public function testCalculateWebhookSignature()
+    {
+        $api = new Api('MOCKSECRETKEY');
+        $calculatedSignature = $api->calculateWebhookSignature("test data");
+        $this->assertEquals('ae82b27dd6dafd0dbfc65faff07160833776cf60915782ef991557e51e4d1782', $calculatedSignature);
+    }
+
+    public function testValidateWebhookSignature()
+    {
+        $api = new Api('MOCKSECRETKEY');
+        $signatureValid = $api->validateWebhookSignature(
+            "test data",
+            "30f01ff4be78d2a2b053ad4a7922c4b4eb2aee75aa5326f2c9b84b52fe4e620e",
+            "test timestamp"
+        );
+        $this->assertEquals(true, $signatureValid);
+    }
 }