Merge pull request #720 from Ayrx/hotp-length-type-check

Added length type check to HOTP and corresponding test

3 files changed, 13 insertions, 2 deletions

diff --git a/cryptography/hazmat/primitives/twofactor/hotp.py b/cryptography/hazmat/primitives/twofactor/hotp.py
index 88bde715..83260225 100644
--- a/cryptography/hazmat/primitives/twofactor/hotp.py
+++ b/cryptography/hazmat/primitives/twofactor/hotp.py
@@ -27,6 +27,9 @@ class HOTP(object):
         if len(key) < 16:
             raise ValueError("Key length has to be at least 128 bits.")
 
+        if not isinstance(length, six.integer_types):
+            raise TypeError("Length parameter must be an integer type")
+
         if length < 6 or length > 8:
             raise ValueError("Length of HOTP has to be between 6 to 8.")
 
diff --git a/docs/hazmat/primitives/twofactor.rst b/docs/hazmat/primitives/twofactor.rst
index 0e781439..3912d483 100644
--- a/docs/hazmat/primitives/twofactor.rst
+++ b/docs/hazmat/primitives/twofactor.rst
@@ -50,7 +50,8 @@ codes (HMAC).
     :raises TypeError: This is raised if the provided ``algorithm`` is not
         :class:`~cryptography.hazmat.primitives.hashes.SHA1()`,
         :class:`~cryptography.hazmat.primitives.hashes.SHA256()` or
-        :class:`~cryptography.hazmat.primitives.hashes.SHA512()`.
+        :class:`~cryptography.hazmat.primitives.hashes.SHA512()` or if the
+        ``length`` parameter is not an integer.
 
     .. method:: generate(counter)
 
@@ -145,7 +146,8 @@ similar to the following code.
     :raises TypeError: This is raised if the provided ``algorithm`` is not
         :class:`~cryptography.hazmat.primitives.hashes.SHA1()`,
         :class:`~cryptography.hazmat.primitives.hashes.SHA256()` or
-        :class:`~cryptography.hazmat.primitives.hashes.SHA512()`.
+        :class:`~cryptography.hazmat.primitives.hashes.SHA512()` or if the
+        ``length`` parameter is not an integer.
 
     .. method:: generate(time)
 
diff --git a/tests/hazmat/primitives/twofactor/test_hotp.py b/tests/hazmat/primitives/twofactor/test_hotp.py
index 4c726b77..0f8c4a53 100644
--- a/tests/hazmat/primitives/twofactor/test_hotp.py
+++ b/tests/hazmat/primitives/twofactor/test_hotp.py
@@ -87,3 +87,9 @@ class TestHOTP(object):
 
         with pytest.raises(InvalidToken):
             hotp.verify(b"123456", counter)
+
+    def test_length_not_int(self, backend):
+        secret = b"12345678901234567890"
+
+        with pytest.raises(TypeError):
+            HOTP(secret, b"foo", SHA1(), backend)