fix py3

1 files changed, 6 insertions, 4 deletions

diff --git a/pyramid/session.py b/pyramid/session.py
index e6635ca1b..3c493a561 100644
--- a/pyramid/session.py
+++ b/pyramid/session.py
@@ -522,9 +522,11 @@ def SignedCookieSessionFactory(
 
     ``serializer``
       An object with 2 methods, ``loads`` and ``dumps``, which will be used
-      to perform serialization and deserialization. The value generated from
-      serialization will be cryptographically signed to prevent tampering.
-      A ``ValueError`` should be raised if deserialization fails.
+      to perform serialization and deserialization.
+      - ``dumps(value)`` should accept a Python object and return a
+        bytestring which can later be deserialized with ``loads``.
+      - ``loads(value)`` should expect to receive a bytestring, generated by
+        ``dumps`` and return a Python object.
 
     .. versionadded: 1.5a3
     """
@@ -563,7 +565,7 @@ class _SignedSerializer(object):
         self.serializer = serializer
 
     def derive_key(self, salt):
-        return hmac.new(self.secret, salt, self.digestmod).digest()
+        return hmac.new(bytes_(self.secret), salt, self.digestmod).digest()
 
     def dumps(self, appstruct):
         salt = os.urandom(self.salt_size)