api: add nonce parameter

rfc3161/api.py

@@ -52,7 +52,7 @@ def get_timestamp(tst):
     except PyAsn1Error, e:
         raise ValueError('not a valid TimeStampToken', e)
 
-def check_timestamp(tst, certificate, data=None, digest=None, hashname=None):
+def check_timestamp(tst, certificate, data=None, digest=None, hashname=None, nonce=None):
     hashname = hashname or 'sha1'
     hashobj = hashlib.new(hashname)
     if digest is None:
@@ -73,6 +73,8 @@ def check_timestamp(tst, certificate, data=None, digest=None, hashname=None):
             certificate = X509.load_cert_string(certificate, X509.FORMAT_DER)
     else:
         return False, "missing certificate"
+    if nonce is not None and int(tst.tst_info['nonce']) != int(nonce):
+        return False, 'nonce is different or missing'
     # check message imprint with respect to locally computed digest
     message_imprint = tst.tst_info.message_imprint
     if message_imprint.hash_algorithm[0] != get_hash_oid(hashname) or \
@@ -142,14 +144,16 @@ class RemoteTimestamper(object):
         self.hashobj = hashlib.new(hashname or 'sha1')
         self.include_tsa_certificate = include_tsa_certificate
 
-    def check_response(self, response, digest):
+    def check_response(self, response, digest, nonce=None):
         '''
            Check validity of a TimeStampResponse
         '''
         tst = response.time_stamp_token
-        return check_timestamp(tst, digest=digest, certificate=self.certificate, hashname=self.hashobj.name)
+        return check_timestamp(tst, digest=digest,
+                certificate=self.certificate, hashname=self.hashobj.name,
+                nonce=nonce)
 
-    def __call__(self, data=None, digest=None, include_tsa_certificate=None):
+    def __call__(self, data=None, digest=None, include_tsa_certificate=None, nonce=None):
         algorithm_identifier = rfc2459.AlgorithmIdentifier()
         algorithm_identifier.setComponentByPosition(0, get_hash_oid(self.hashobj.name))
         message_imprint = rfc3161.MessageImprint()
@@ -165,6 +169,8 @@ class RemoteTimestamper(object):
         request = rfc3161.TimeStampReq()
         request.setComponentByPosition(0, 'v1')
         request.setComponentByPosition(1, message_imprint)
+        if nonce is not None:
+            request.setComponentByPosition(3, int(nonce))
         request.setComponentByPosition(4, include_tsa_certificate if include_tsa_certificate is not None else self.include_tsa_certificate)
         binary_request = encoder.encode(request)
         http_request = urllib2.Request(self.url, binary_request,
@@ -180,7 +186,7 @@ class RemoteTimestamper(object):
         tst_response, substrate = decoder.decode(response, asn1Spec=rfc3161.TimeStampResp())
         if substrate:
             return False, 'Extra data returned'
-        result, message = self.check_response(tst_response, digest)
+        result, message = self.check_response(tst_response, digest, nonce=nonce)
         if result:
             return encoder.encode(tst_response.time_stamp_token), ''
         else:

tests/api.py

@@ -35,3 +35,17 @@ class Rfc3161(unittest.TestCase):
         self.assertNotEqual(value, None)
         self.assertEqual(substrate, '')
 
+    def test_teszt_e_szigno_hu_with_nonce(self):
+        PUBLIC_TSA_SERVER = 'https://teszt.e-szigno.hu:440/tsa'
+        USERNAME = 'teszt'
+        PASSWORD = 'teszt'
+        CERTIFICATE = os.path.join(os.path.dirname(__file__),
+                '../data/e_szigno_test_tsa2.crt')
+        data = 'xx'
+        certificate = file(CERTIFICATE).read()
+        value, substrate = rfc3161.RemoteTimestamper(
+                PUBLIC_TSA_SERVER, certificate=certificate, username=USERNAME,
+                password=PASSWORD, hashname='sha256')(data=data, nonce=2)
+        self.assertIsInstance(rfc3161.get_timestamp(value), datetime.datetime)
+        self.assertNotEqual(value, None)
+        self.assertEqual(substrate, '')