Added signing file

djadyen/notifications/signing.py

@@ -0,0 +1,43 @@
+import base64
+import binascii
+import hashlib
+import hmac
+import logging
+
+from djadyen import settings
+
+logger = logging.getLogger("adyen")
+
+
+def get_signature(params):
+    """
+    Description of how the HMAC can be signed can be found here
+
+    https://docs.adyen.com/development-resources/webhooks/verify-hmac-signatures
+    """
+    hmac_key = binascii.a2b_hex(settings.DJADYEN_NOTIFICATION_KEY)
+
+    logger.debug("Params: %s", params)
+
+    signing_string = "{part1}:{part2}".format(
+        part1="{psp_reference}:{original_reference}:{merchant_account_code}".format(
+            psp_reference=params.get("pspReference", ""),
+            original_reference=params.get("originalReference", ""),
+            merchant_account_code=params.get("merchantAccountCode", ""),
+        ),
+        part2="{merchant_reference}:{value}:{currency}:{event_code}:{success}".format(
+            merchant_reference=params.get("merchantReference", ""),
+            value=params.get("amount", {}).get("value", ""),
+            currency=params.get("amount", {}).get("currency", ""),
+            event_code=params.get("eventCode", ""),
+            success=params.get("success", ""),
+        ),
+    )
+    logger.debug("Signing Params: %s", signing_string)
+
+    hmac_string = hmac.new(hmac_key, signing_string.encode("utf-8"), hashlib.sha256)
+    logger.debug("HMAC: %s", hmac_string)
+
+    signature = base64.b64encode(hmac_string.digest()).decode("utf-8")
+    logger.debug("signature: %s", signature)
+    return signature