Fix typo in docstring for key argument

Fixes #80

Author: kislyuk

signxml/__init__.py

@@ -287,15 +287,15 @@ def sign(self, data, key=None, passphrase=None, cert=None, reference_uri=None, k
         :param data: Data to sign
         :type data: String, file-like object, or XML ElementTree Element API compatible object
         :param key:
-            Key to be used for signing. When signing with a certificate or RSA/DSA/ECDSA key, this can be a string
-            containing a PEM-formatted key, or a :py:class:`cryptography.hazmat.primitives.interfaces.RSAPublicKey`,
-            :py:class:`cryptography.hazmat.primitives.interfaces.DSAPublicKey`, or
-            :py:class:`cryptography.hazmat.primitives.interfaces.EllipticCurvePublicKey` object. When signing with a
+            Key to be used for signing. When signing with a certificate or RSA/DSA/ECDSA key, this can be a string/bytes
+            containing a PEM-formatted key, or a :py:class:`cryptography.hazmat.primitives.interfaces.RSAPrivateKey`,
+            :py:class:`cryptography.hazmat.primitives.interfaces.DSAPrivateKey`, or
+            :py:class:`cryptography.hazmat.primitives.interfaces.EllipticCurvePrivateKey` object. When signing with a
             HMAC, this should be a string containing the shared secret.
         :type key:
-            string, :py:class:`cryptography.hazmat.primitives.interfaces.RSAPublicKey`,
-            :py:class:`cryptography.hazmat.primitives.interfaces.DSAPublicKey`, or
-            :py:class:`cryptography.hazmat.primitives.interfaces.EllipticCurvePublicKey` object
+            string, bytes, :py:class:`cryptography.hazmat.primitives.interfaces.RSAPrivateKey`,
+            :py:class:`cryptography.hazmat.primitives.interfaces.DSAPrivateKey`, or
+            :py:class:`cryptography.hazmat.primitives.interfaces.EllipticCurvePrivateKey` object
         :param passphrase: Passphrase to use to decrypt the key, if any.
         :type passphrase: string
         :param cert:

signxml/util/__init__.py

@@ -223,6 +223,7 @@ def verify_x509_cert_chain(cert_chain, ca_pem_file=None, ca_path=None):
     or being part of a certification chain that terminates in a certificate containing the validation key.
     No ordering is implied by the above constraints"
     """
+    # TODO: migrate to Cryptography (pending cert validation support) or https://github.com/wbond/certvalidator
     from OpenSSL import SSL
     context = SSL.Context(SSL.TLSv1_METHOD)
     if ca_pem_file is None and ca_path is None: