Index: Lib/zipfile.py
===================================================================
--- Lib/zipfile.py	(revision 65056)
+++ Lib/zipfile.py	(working copy)
@@ -2,7 +2,7 @@
 Read and write ZIP files.
 """
 import struct, os, time, sys, shutil
-import binascii, cStringIO
+import binascii, cStringIO, stat
 
 try:
     import zlib # We may need its compression method
@@ -1064,6 +1064,8 @@
             zinfo = ZipInfo(filename=zinfo_or_arcname,
                             date_time=time.localtime(time.time())[:6])
             zinfo.compress_type = self.compression
+            # zinfo.external_attr = 0600 << 16
+            zinfo.external_attr = (stat.S_IRUSR | stat.S_IWUSR) << 16
         else:
             zinfo = zinfo_or_arcname
 
Index: Lib/test/test_zipfile.py
===================================================================
--- Lib/test/test_zipfile.py	(revision 65056)
+++ Lib/test/test_zipfile.py	(working copy)
@@ -372,6 +372,20 @@
         # remove the test file subdirectories
         shutil.rmtree(os.path.join(os.getcwd(), 'ziptest2dir'))
 
+    def zip_test_writestr_permissions(self, f, compression):
+        # Make sure that writestr creates files with mode 0600,
+        # when it is passed a name rather than a ZipInfo instance.
+
+        self.makeTestArchive(f, compression)
+        zipfp = zipfile.ZipFile(f, "r")
+        zinfo = zipfp.getinfo('strfile')
+        self.assertEqual(zinfo.external_attr, 0600 << 16)
+
+    def test_writestr_permissions(self):
+        for f in (TESTFN2, TemporaryFile(), StringIO()):
+            self.zip_test_writestr_permissions(f, zipfile.ZIP_STORED)
+
+
     def tearDown(self):
         os.remove(TESTFN)
         os.remove(TESTFN2)