diff --git a/gcloud/storage/_helpers.py b/gcloud/storage/_helpers.py
index b9e902deb526..7970c78c5136 100644
--- a/gcloud/storage/_helpers.py
+++ b/gcloud/storage/_helpers.py
@@ -17,6 +17,9 @@
 These are *not* part of the API.
 """
 
+from Crypto.Hash import MD5
+import base64
+
 
 class _PropertyMixin(object):
     """Abstract mixin for cloud storage classes with associated propertties.
@@ -187,3 +190,30 @@ def _setter(self, value):
         self._patch_properties({fieldname: value})
 
     return property(_getter, _setter)
+
+
+def _write_buffer_to_hash(buffer_object, hash_obj, digest_block_size=8192):
+    """Read blocks from a buffer and update a hash with them.
+
+    :type buffer_object: bytes buffer
+    :param buffer_object: Buffer containing bytes used to update a hash object.
+    """
+    block = buffer_object.read(digest_block_size)
+
+    while len(block) > 0:
+        hash_obj.update(block)
+        # Update the block for the next iteration.
+        block = buffer_object.read(digest_block_size)
+
+
+def _base64_md5hash(buffer_object):
+    """Get MD5 hash of bytes (as base64).
+
+    :type buffer_object: bytes buffer
+    :param buffer_object: Buffer containing bytes used to compute an MD5
+                          hash (as base64).
+    """
+    hash_obj = MD5.new()
+    _write_buffer_to_hash(buffer_object, hash_obj)
+    digest_bytes = hash_obj.digest()
+    return base64.b64encode(digest_bytes)
diff --git a/gcloud/storage/test__helpers.py b/gcloud/storage/test__helpers.py
index b550f905034d..d98634ea5c13 100644
--- a/gcloud/storage/test__helpers.py
+++ b/gcloud/storage/test__helpers.py
@@ -237,6 +237,53 @@ def _patch_properties(self, mapping):
         self.assertEqual(test._patched, {'solfege': 'Latido'})
 
 
+class Test__base64_md5hash(unittest2.TestCase):
+
+    def _callFUT(self, bytes_to_sign):
+        from gcloud.storage._helpers import _base64_md5hash
+        return _base64_md5hash(bytes_to_sign)
+
+    def test_it(self):
+        from io import BytesIO
+        BYTES_TO_SIGN = b'FOO'
+        BUFFER = BytesIO()
+        BUFFER.write(BYTES_TO_SIGN)
+        BUFFER.seek(0)
+
+        SIGNED_CONTENT = self._callFUT(BUFFER)
+        self.assertEqual(SIGNED_CONTENT, b'kBiQqOnIz21aGlQrIp/r/w==')
+
+    def test_it_with_stubs(self):
+        from gcloud._testing import _Monkey
+        from gcloud.storage import _helpers as MUT
+
+        class _Buffer(object):
+
+            def __init__(self, return_vals):
+                self.return_vals = return_vals
+                self._block_sizes = []
+
+            def read(self, block_size):
+                self._block_sizes.append(block_size)
+                return self.return_vals.pop()
+
+        BASE64 = _Base64()
+        DIGEST_VAL = object()
+        BYTES_TO_SIGN = b'BYTES_TO_SIGN'
+        BUFFER = _Buffer([b'', BYTES_TO_SIGN])
+        MD5 = _MD5(DIGEST_VAL)
+
+        with _Monkey(MUT, base64=BASE64, MD5=MD5):
+            SIGNED_CONTENT = self._callFUT(BUFFER)
+
+        self.assertEqual(BUFFER._block_sizes, [8192, 8192])
+        self.assertTrue(SIGNED_CONTENT is DIGEST_VAL)
+        self.assertEqual(BASE64._called_b64encode, [DIGEST_VAL])
+        self.assertEqual(MD5._new_called, [None])
+        self.assertEqual(MD5.hash_obj.num_digest_calls, 1)
+        self.assertEqual(MD5.hash_obj._blocks, [BYTES_TO_SIGN])
+
+
 class _Connection(object):
 
     def __init__(self, *responses):
@@ -247,3 +294,39 @@ def api_request(self, **kw):
         self._requested.append(kw)
         response, self._responses = self._responses[0], self._responses[1:]
         return response
+
+
+class _MD5Hash(object):
+
+    def __init__(self, digest_val):
+        self.digest_val = digest_val
+        self.num_digest_calls = 0
+        self._blocks = []
+
+    def update(self, block):
+        self._blocks.append(block)
+
+    def digest(self):
+        self.num_digest_calls += 1
+        return self.digest_val
+
+
+class _MD5(object):
+
+    def __init__(self, digest_val):
+        self.hash_obj = _MD5Hash(digest_val)
+        self._new_called = []
+
+    def new(self, data=None):
+        self._new_called.append(data)
+        return self.hash_obj
+
+
+class _Base64(object):
+
+    def __init__(self):
+        self._called_b64encode = []
+
+    def b64encode(self, value):
+        self._called_b64encode.append(value)
+        return value
diff --git a/regression/storage.py b/regression/storage.py
index f7a657452e9c..342f240761cb 100644
--- a/regression/storage.py
+++ b/regression/storage.py
@@ -12,8 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from Crypto.Hash import MD5
-import base64
 import httplib2
 import tempfile
 import time
@@ -21,6 +19,7 @@
 
 from gcloud import exceptions
 from gcloud import storage
+from gcloud.storage._helpers import _base64_md5hash
 from gcloud.storage import _implicit_environ
 
 
@@ -96,18 +95,12 @@ class TestStorageFiles(unittest2.TestCase):
         }
     }
 
-    @staticmethod
-    def _get_base64_md5hash(filename):
-        with open(filename, 'rb') as file_obj:
-            hash = MD5.new(data=file_obj.read())
-        digest_bytes = hash.digest()
-        return base64.b64encode(digest_bytes)
-
     @classmethod
     def setUpClass(cls):
         super(TestStorageFiles, cls).setUpClass()
         for file_data in cls.FILES.values():
-            file_data['hash'] = cls._get_base64_md5hash(file_data['path'])
+            with open(file_data['path'], 'rb') as file_obj:
+                file_data['hash'] = _base64_md5hash(file_obj)
         cls.bucket = SHARED_BUCKETS['test_bucket']
 
     def setUp(self):