3 files changed, 15 insertions, 27 deletions
diff --git a/src/cryptography/hazmat/primitives/twofactor/hotp.py b/src/cryptography/hazmat/primitives/twofactor/hotp.py
index ba228b40..f59f551c 100644
--- a/src/cryptography/hazmat/primitives/twofactor/hotp.py
+++ b/src/cryptography/hazmat/primitives/twofactor/hotp.py
@@ -15,6 +15,7 @@ from cryptography.hazmat.backends.interfaces import HMACBackend
 from cryptography.hazmat.primitives import constant_time, hmac
 from cryptography.hazmat.primitives.hashes import SHA1, SHA256, SHA512
 from cryptography.hazmat.primitives.twofactor import InvalidToken
+from cryptography.hazmat.primitives.twofactor.utils import generate_uri
 
 
 class HOTP(object):
@@ -59,3 +60,8 @@ class HOTP(object):
         offset = six.indexbytes(hmac_value, len(hmac_value) - 1) & 0b1111
         p = hmac_value[offset:offset + 4]
         return struct.unpack(">I", p)[0] & 0x7fffffff
+
+    def get_provisioning_uri(self, account_name, counter, issuer=None):
+        return generate_uri(self, 'hotp', account_name, issuer, [
+            ('counter', int(counter)),
+        ])
diff --git a/src/cryptography/hazmat/primitives/twofactor/totp.py b/src/cryptography/hazmat/primitives/twofactor/totp.py
index 03df9292..9c8eddad 100644
--- a/src/cryptography/hazmat/primitives/twofactor/totp.py
+++ b/src/cryptography/hazmat/primitives/twofactor/totp.py
@@ -11,6 +11,7 @@ from cryptography.hazmat.backends.interfaces import HMACBackend
 from cryptography.hazmat.primitives import constant_time
 from cryptography.hazmat.primitives.twofactor import InvalidToken
 from cryptography.hazmat.primitives.twofactor.hotp import HOTP
+from cryptography.hazmat.primitives.twofactor.utils import generate_uri
 
 
 class TOTP(object):
@@ -31,3 +32,8 @@ class TOTP(object):
     def verify(self, totp, time):
         if not constant_time.bytes_eq(self.generate(time), totp):
             raise InvalidToken("Supplied TOTP value does not match.")
+
+    def get_provisioning_uri(self, account_name, issuer=None):
+        return generate_uri(self._hotp, 'totp', account_name, issuer, [
+            ('period', int(self._time_step)),
+        ])
diff --git a/src/cryptography/hazmat/primitives/twofactor/utils.py b/src/cryptography/hazmat/primitives/twofactor/utils.py
index 43f50b30..89d38ff2 100644
--- a/src/cryptography/hazmat/primitives/twofactor/utils.py
+++ b/src/cryptography/hazmat/primitives/twofactor/utils.py
@@ -5,25 +5,7 @@ import base64
 from six.moves.urllib.parse import quote, urlencode
 
 
-__all__ = ['get_provisioning_uri']
-
-
-def get_provisioning_uri(otp, account_name, issuer=None, counter=None):
-    """Generates a provisioning URI which can be recognized by Two-Factor
-    Authentication Apps. See also: http://git.io/vkvvY
-
-    :param otp: An instance of
-                :class:`cryptography.hazmat.primitives.twofactor.hotp.HOTP` or
-                :class:`cryptography.hazmat.primitives.twofactor.totp.TOTP`.
-    :param account_name: The display name of account, such as
-                         ``'Alice Smith'`` or ``'alice@example.com'``.
-    :param issuer: The display name of issuer.
-    :param counter: The current value of counter. It is required for HOTP.
-    :return: The URI string.
-    :raises RuntimeError: if counter is missing but otp type is HOTP
-    """
-    hotp = getattr(otp, '_hotp', otp)
-
+def generate_uri(hotp, type_name, account_name, issuer, extra_parameters):
     parameters = [
         ('digits', hotp._length),
         ('secret', base64.b32encode(hotp._key)),
@@ -33,16 +15,10 @@ def get_provisioning_uri(otp, account_name, issuer=None, counter=None):
     if issuer is not None:
         parameters.append(('issuer', issuer))
 
-    if hotp is otp:
-        if counter is None:
-            raise RuntimeError('"counter" is required for HOTP')
-        parameters.append(('counter', int(counter)))
-
-    if hasattr(otp, '_time_step'):
-        parameters.append(('period', int(otp._time_step)))
+    parameters.extend(extra_parameters)
 
     uriparts = {
-        'type': otp.__class__.__name__.lower(),
+        'type': type_name,
         'label': ('%s:%s' % (quote(issuer), quote(account_name)) if issuer
                   else quote(account_name)),
         'parameters': urlencode(parameters),