diff --git a/src/calibre/ebooks/conversion/plugins/epub_input.py b/src/calibre/ebooks/conversion/plugins/epub_input.py
index 409c128836..9d29fbbbf2 100644
--- a/src/calibre/ebooks/conversion/plugins/epub_input.py
+++ b/src/calibre/ebooks/conversion/plugins/epub_input.py
@@ -3,7 +3,7 @@ __license__ = 'GPL 3'
 __copyright__ = '2009, Kovid Goyal <kovid@kovidgoyal.net>'
 __docformat__ = 'restructuredtext en'
 
-import os
+import os, re
 from itertools import cycle
 
 from calibre.customize.conversion import InputFormatPlugin, OptionRecommendation
@@ -37,9 +37,10 @@ class EPUBInput(InputFormatPlugin):
     def process_encryption(self, encfile, opf, log):
         from lxml import etree
         import uuid, hashlib
-        idpf_key = opf.unique_identifier
+        idpf_key = opf.raw_unique_identifier
         if idpf_key:
-            idpf_key = hashlib.sha1(idpf_key).digest()
+            idpf_key = re.sub(u'\u0020\u0009\u000d\u000a', u'', idpf_key)
+            idpf_key = hashlib.sha1(idpf_key.encode('utf-8')).digest()
         key = None
         for item in opf.identifier_iter():
             scheme = None
diff --git a/src/calibre/ebooks/oeb/polish/container.py b/src/calibre/ebooks/oeb/polish/container.py
index 5dd478b1ce..c5c0c5e16e 100644
--- a/src/calibre/ebooks/oeb/polish/container.py
+++ b/src/calibre/ebooks/oeb/polish/container.py
@@ -940,7 +940,7 @@ class EpubContainer(Container):
         if not fonts:
             return
 
-        package_id = unique_identifier = idpf_key = None
+        package_id = raw_unique_identifier = idpf_key = None
         for attrib, val in self.opf.attrib.iteritems():
             if attrib.endswith('unique-identifier'):
                 package_id = val
@@ -948,10 +948,12 @@ class EpubContainer(Container):
         if package_id is not None:
             for elem in self.opf_xpath('//*[@id=%r]'%package_id):
                 if elem.text:
-                    unique_identifier = elem.text.rpartition(':')[-1]
+                    raw_unique_identifier = elem.text
                     break
-        if unique_identifier is not None:
-            idpf_key = hashlib.sha1(unique_identifier).digest()
+        if raw_unique_identifier is not None:
+            idpf_key = raw_unique_identifier
+            idpf_key = re.sub(u'\u0020\u0009\u000d\u000a', u'', idpf_key)
+            idpf_key = hashlib.sha1(idpf_key.encode('utf-8')).digest()
         key = None
         for item in self.opf_xpath('//*[local-name()="metadata"]/*'
                                    '[local-name()="identifier"]'):