diff --git a/Authors b/Authors
index f84155f6..4d9bc5f2 100644
--- a/Authors
+++ b/Authors
@@ -14,6 +14,7 @@ Arvind Somya <asomya@cisco.com>
 Bilal Akhtar <bilalakhtar@ubuntu.com>
 Brad Hall <brad@nicira.com>
 Brad McConnell <bmcconne@rackspace.com>
+Brendan Maguire <B_Maguire@Dell.com>
 Brian Lamar <brian.lamar@rackspace.com>
 Brian Schott <bschott@isi.edu>
 Brian Waldon <brian.waldon@rackspace.com>
diff --git a/nova/auth/signer.py b/nova/auth/signer.py
index 744e315d..c0468021 100644
--- a/nova/auth/signer.py
+++ b/nova/auth/signer.py
@@ -67,6 +67,8 @@ class Signer(object):
         self.hmac = hmac.new(secret_key, digestmod=hashlib.sha1)
         if hashlib.sha256:
             self.hmac_256 = hmac.new(secret_key, digestmod=hashlib.sha256)
+        else:
+            self.hmac_256 = None
 
     def s3_authorization(self, headers, verb, path):
         """Generate S3 authorization string."""
@@ -77,7 +79,12 @@ class Signer(object):
         return b64_hmac
 
     def generate(self, params, verb, server_string, path):
-        """Generate auth string according to what SignatureVersion is given."""
+        """Generate auth string according to what SignatureVersion is given.
+
+        The signature method defaults to SHA256 if available, or falls back to
+        SHA1 if not.
+
+        """
         if params['SignatureVersion'] == '0':
             return self._calc_signature_0(params)
         if params['SignatureVersion'] == '1':
@@ -150,6 +157,5 @@ class Signer(object):
 
 
 if __name__ == '__main__':
-    print Signer('foo').generate({'SignatureMethod': 'HmacSHA256',
-                                  'SignatureVersion': '2'},
-                                 'get', 'server', '/foo')
+    print Signer('foo').generate({'SignatureVersion': '2'}, 'get', 'server',
+                                  '/foo')
diff --git a/nova/tests/test_signer.py b/nova/tests/test_signer.py
new file mode 100644
index 00000000..bbfd09be
--- /dev/null
+++ b/nova/tests/test_signer.py
@@ -0,0 +1,92 @@
+# vim: tabstop=4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""Tests for Signer."""
+
+from nova import exception
+from nova import test
+from nova.auth import signer
+
+
+class ClassWithStrRepr(object):
+    def __repr__(self):
+        return 'A string representation'
+
+
+class SignerTestCase(test.TestCase):
+    def setUp(self):
+        super(SignerTestCase, self).setUp()
+        self.signer = signer.Signer('uV3F3YluFJax1cknvbcGwgjvx4QpvB+leU8dUj2o')
+
+    def tearDown(self):
+        super(SignerTestCase, self).tearDown()
+
+    # S3 Authorization Signing input & output examples taken from here:
+    # http://docs.amazonwebservices.com/AmazonS3/latest/dev/
+    def test_s3_authorization_get(self):
+        self.assertEquals('xXjDGYUmKxnwqr5KXNPGldn5LbA=',
+                          self.signer.s3_authorization(
+                                {'Date': 'Tue, 27 Mar 2007 19:36:42 +0000'},
+                                'GET',
+                                '/johnsmith/photos/puppy.jpg'))
+
+    def test_s3_authorization_put(self):
+        self.assertEquals('hcicpDDvL9SsO6AkvxqmIWkmOuQ=',
+                          self.signer.s3_authorization(
+                                {'Date': 'Tue, 27 Mar 2007 21:15:45 +0000',
+                                 'Content-Length': '94328',
+                                 'Content-Type': 'image/jpeg'},
+                                'PUT',
+                                '/johnsmith/photos/puppy.jpg'))
+
+    def test_generate_using_version_2(self):
+        self.assertEquals('clXalhbLZXxEuI32OoX+OeXsN6Mr2q4jzGyIDAr4RZg=',
+                          self.signer.generate(
+                                {'SignatureMethod': 'HmacSHA256',
+                                 'SignatureVersion': '2'},
+                                'GET', 'server', '/foo'))
+
+    def test_generate_force_HmacSHA1(self):
+        # Stub out haslib.sha256
+        import hashlib
+        self.stubs.Set(hashlib, 'sha256', None)
+
+        # Create Signer again now that hashlib.sha256 is None
+        self.signer = signer.Signer(
+                        'uV3F3YluFJax1cknvbcGwgjvx4QpvB+leU8dUj2o')
+        self.assertEquals('uJTByiDIcgB65STrS5i2egQgd+U=',
+                          self.signer.generate({'SignatureVersion': '2'},
+                                               'GET', 'server', '/foo'))
+
+    def test_generate_with_unicode_param(self):
+        self.assertEquals('clXalhbLZXxEuI32OoX+OeXsN6Mr2q4jzGyIDAr4RZg=',
+                          self.signer.generate({'SignatureVersion': u'2'},
+                                               'GET', 'server', '/foo'))
+
+    def test_generate_with_non_string_or_unicode_param(self):
+        self.assertEquals('99IAgCkhTR2aMTgRobnzKGuNxVFSdb7vlQRvnj3Urqk=',
+                          self.signer.generate(
+                              {'AnotherParam': ClassWithStrRepr(),
+                               'SignatureVersion': '2'},
+                              'GET', 'server', '/foo'))
+
+    def test_generate_unknown_version(self):
+        with self.assertRaises(exception.Error):
+            self.signer.generate({'SignatureMethod': 'HmacSHA256',
+                                  'SignatureVersion': '9'},
+                                 'GET', 'server', '/foo')