Start with signature code

adyen/interface.py

@@ -1,3 +1,81 @@
 import logging
 logger = logging.getLogger(__name__)
 
+from adyen import settings
+
+
+class PaymentInterface(object):
+    """
+    Wrapper around Adyen API calls.
+
+    This object is stateless and does not use any settings, hence it can be
+    used easily in non-Django applications.
+    """
+
+    # URL's for single- and multi-page checkouts (test and production)
+    TEST_URL_BASE = 'https://test.adyen.com/hpp/'
+    TEST_URL_SINGLE = TEST_URL_BASE + 'pay.shtml'
+    TEST_URL_MULTIPLE = TEST_URL_BASE + 'select.shtml'
+
+    PROD_URL_BASE = 'https://live.adyen.com/hpp/'
+    PROD_URL_SINGLE = TEST_URL_BASE + 'pay.shtml'
+    PROD_URL_MULTIPLE = TEST_URL_BASE + 'select.shtml'
+
+    # Fields used for signing payment requests
+    REQUEST_SIGNATURE_FIELDS = \
+        ('paymentAmount', 'currencyCode', 'shipBeforeDate',
+         'merchantReference', 'skinCode', 'merchantAccount',
+         'sessionValidity', 'shopperEmail', 'shopperReference',
+         'allowedMethods', 'blockedMethods', 'shopperStatement',
+         'billingAddressType')
+
+    # Fields used for signing billing addresses
+    ADDRESS_SIGNATURE_FIELDS = \
+        ('billingAddress.street', 'billingAddress.houseNumberOrName',
+         'billingAddress.city', 'billingAddress.postalCode',
+         'billingAddress.stateOrProvince', 'billingAddress.country')
+
+    # Fields used for verification of result signatures
+    RESULT_SIGNATURE_FIELDS = \
+        ('authResult', 'pspReference', 'merchantReference', 'skinCode')
+
+    def __init__(self, params=None, request=None):
+        """
+        Initialize the interface.
+        """
+        assert request or params, \
+            'Please specify either a request or a set of parameters'
+
+        if not params:
+            params = request.REQUEST
+
+        self.params = params
+
+        # We haven't parsed anything yet
+        self.parsed = False
+
+    @staticmethod
+    def _sign_plaintext(plaintext, secret):
+        """
+        Sign the string `plaintext` with a given `secret` using HMAC and
+        encode the result as a base64 encoded string.
+
+        Source: Adyen Python signature implementation example.
+        """
+        import base64
+        import hmac
+        import hashlib
+
+        hm = hmac.new(secret, data, hashlib.sha1)
+        return base64.encodestring(hm.digest()).strip()
+
+    @staticmethod
+    def _data_to_plaintext(data, fields):
+        """
+        Concatenate the specified `fields` from the `data` dictionary.
+        """
+        plaintext = ''
+        for field in fields:
+            plaintext += data.get(field, '')
+
+        return plaintext