diff --git a/src/calibre/ebooks/conversion/plugins/epub_input.py b/src/calibre/ebooks/conversion/plugins/epub_input.py
index 70a561226d..8f2f32577f 100644
--- a/src/calibre/ebooks/conversion/plugins/epub_input.py
+++ b/src/calibre/ebooks/conversion/plugins/epub_input.py
@@ -9,6 +9,19 @@ from itertools import cycle
 from calibre.customize.conversion import InputFormatPlugin, OptionRecommendation
 
 ADOBE_OBFUSCATION =  'http://ns.adobe.com/pdf/enc#RC'
+IDPF_OBFUSCATION = 'http://www.idpf.org/2008/embedding'
+
+def decrypt_font(key, path, algorithm):
+    is_adobe = algorithm == ADOBE_OBFUSCATION
+    crypt_len = 1024 if is_adobe else 1040
+    with open(path, 'rb') as f:
+        raw = f.read()
+    crypt = bytearray(raw[:crypt_len])
+    key = cycle(iter(bytearray(key)))
+    decrypt = bytes(bytearray(x^key.next() for x in crypt))
+    with open(path, 'wb') as f:
+        f.write(decrypt)
+        f.write(raw[crypt_len:])
 
 class EPUBInput(InputFormatPlugin):
 
@@ -20,18 +33,6 @@ class EPUBInput(InputFormatPlugin):
 
     recommendations = set([('page_breaks_before', '/', OptionRecommendation.MED)])
 
-    def decrypt_font(self, key, path, algorithm):
-        is_adobe = algorithm == ADOBE_OBFUSCATION
-        crypt_len = 1024 if is_adobe else 1040
-        with open(path, 'rb') as f:
-            raw = f.read()
-        crypt = bytearray(raw[:crypt_len])
-        key = cycle(iter(bytearray(key)))
-        decrypt = bytes(bytearray(x^key.next() for x in crypt))
-        with open(path, 'wb') as f:
-            f.write(decrypt)
-            f.write(raw[crypt_len:])
-
     def process_encryption(self, encfile, opf, log):
         from lxml import etree
         import uuid, hashlib
@@ -58,8 +59,7 @@ class EPUBInput(InputFormatPlugin):
             root = etree.parse(encfile)
             for em in root.xpath('descendant::*[contains(name(), "EncryptionMethod")]'):
                 algorithm = em.get('Algorithm', '')
-                if algorithm not in {ADOBE_OBFUSCATION,
-                        'http://www.idpf.org/2008/embedding'}:
+                if algorithm not in {ADOBE_OBFUSCATION, IDPF_OBFUSCATION}:
                     return False
                 cr = em.getparent().xpath('descendant::*[contains(name(), "CipherReference")]')[0]
                 uri = cr.get('URI')
@@ -67,7 +67,7 @@ class EPUBInput(InputFormatPlugin):
                 tkey = (key if algorithm == ADOBE_OBFUSCATION else idpf_key)
                 if (tkey and os.path.exists(path)):
                     self._encrypted_font_uris.append(uri)
-                    self.decrypt_font(tkey, path, algorithm)
+                    decrypt_font(tkey, path, algorithm)
             return True
         except:
             import traceback
diff --git a/src/calibre/ebooks/oeb/polish/__init__.py b/src/calibre/ebooks/oeb/polish/__init__.py
new file mode 100644
index 0000000000..07138c49b8
--- /dev/null
+++ b/src/calibre/ebooks/oeb/polish/__init__.py
@@ -0,0 +1,11 @@
+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:fdm=marker:ai
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__   = 'GPL v3'
+__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+
+
diff --git a/src/calibre/ebooks/oeb/polish/container.py b/src/calibre/ebooks/oeb/polish/container.py
new file mode 100644
index 0000000000..c37d2aeb44
--- /dev/null
+++ b/src/calibre/ebooks/oeb/polish/container.py
@@ -0,0 +1,354 @@
+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:fdm=marker:ai
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__   = 'GPL v3'
+__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+import os, posixpath, logging, sys, hashlib, uuid
+from urllib import unquote as urlunquote
+
+from lxml import etree
+
+from calibre import guess_type, CurrentDir
+from calibre.ebooks.chardet import xml_to_unicode
+from calibre.ebooks.conversion.plugins.epub_input import (
+    ADOBE_OBFUSCATION, IDPF_OBFUSCATION, decrypt_font)
+from calibre.ebooks.conversion.preprocess import HTMLPreProcessor, CSSPreProcessor
+from calibre.ebooks.mobi import MobiError
+from calibre.ebooks.mobi.reader.headers import MetadataHeader
+from calibre.ebooks.oeb.base import OEB_DOCS, _css_logger, OEB_STYLES, OPF2_NS
+from calibre.ebooks.oeb.polish.errors import InvalidBook, DRMError
+from calibre.ebooks.oeb.parse_utils import NotHTML, parse_html, RECOVER_PARSER
+from calibre.ptempfile import PersistentTemporaryDirectory
+from calibre.utils.fonts.sfnt.container import Sfnt
+from calibre.utils.ipc.simple_worker  import fork_job, WorkerError
+from calibre.utils.logging import default_log
+from calibre.utils.zipfile import ZipFile
+
+exists, join, relpath = os.path.exists, os.path.join, os.path.relpath
+
+OEB_FONTS = {guess_type('a.ttf')[0], guess_type('b.ttf')[0]}
+
+class Container(object):
+
+    def __init__(self, rootpath, opfpath, log):
+        self.root = os.path.abspath(rootpath)
+        self.log = log
+        self.html_preprocessor = HTMLPreProcessor()
+        self.css_preprocessor = CSSPreProcessor()
+
+        self.parsed_cache = {}
+        self.mime_map = {}
+        self.name_path_map = {}
+
+        # Map of relative paths with '/' separators from root of unzipped ePub
+        # to absolute paths on filesystem with os-specific separators
+        opfpath = os.path.abspath(opfpath)
+        for dirpath, _dirnames, filenames in os.walk(self.root):
+            for f in filenames:
+                path = join(dirpath, f)
+                name = relpath(path, self.root).replace(os.sep, '/')
+                self.name_path_map[name] = path
+                self.mime_map[name] = guess_type(path)[0]
+                # Special case if we have stumbled onto the opf
+                if path == opfpath:
+                    self.opf_name = name
+                    self.opf_dir = posixpath.dirname(path)
+                    self.mime_map[name] = guess_type('a.opf')[0]
+
+        # Update mime map with data from the OPF
+        for item in self.opf.xpath(
+                '//opf:manifest/opf:item[@href and @media-type]',
+                namespaces={'opf':OPF2_NS}):
+            href = item.get('href')
+            self.mime_map[self.href_to_name(href)] = item.get('media-type')
+
+
+    def href_to_name(self, href, base=None):
+        if base is None:
+            base = self.opf_dir
+        href = urlunquote(href.partition('#')[0])
+        fullpath = posixpath.abspath(posixpath.join(base, href))
+        return self.relpath(fullpath)
+
+    def relpath(self, path):
+        return relpath(path, self.root)
+
+    def decode(self, data):
+        """Automatically decode :param:`data` into a `unicode` object."""
+        def fix_data(d):
+            return d.replace('\r\n', '\n').replace('\r', '\n')
+        if isinstance(data, unicode):
+            return fix_data(data)
+        bom_enc = None
+        if data[:4] in {b'\0\0\xfe\xff', b'\xff\xfe\0\0'}:
+            bom_enc = {b'\0\0\xfe\xff':'utf-32-be',
+                       b'\xff\xfe\0\0':'utf-32-le'}[data[:4]]
+            data = data[4:]
+        elif data[:2] in {b'\xff\xfe', b'\xfe\xff'}:
+            bom_enc = {b'\xff\xfe':'utf-16-le', b'\xfe\xff':'utf-16-be'}[data[:2]]
+            data = data[2:]
+        elif data[:3] == b'\xef\xbb\xbf':
+            bom_enc = 'utf-8'
+            data = data[3:]
+        if bom_enc is not None:
+            try:
+                return fix_data(data.decode(bom_enc))
+            except UnicodeDecodeError:
+                pass
+        try:
+            return fix_data(data.decode('utf-8'))
+        except UnicodeDecodeError:
+            pass
+        data, _ = xml_to_unicode(data)
+        return fix_data(data)
+
+    def parse_xml(self, data):
+        data = xml_to_unicode(data, strip_encoding_pats=True, assume_utf8=True,
+                             resolve_entities=True)[0].strip()
+        return etree.fromstring(data, parser=RECOVER_PARSER)
+
+    def parse_xhtml(self, data, fname):
+        try:
+            return parse_html(data, log=self.log,
+                    decoder=self.decode,
+                    preprocessor=self.html_preprocessor,
+                    filename=fname, non_html_file_tags={'ncx'})
+        except NotHTML:
+            return self.parse_xml(data)
+
+    def parse(self, path, mime):
+        with open(path, 'rb') as src:
+            data = src.read()
+        if mime in OEB_DOCS:
+            data = self.parse_xhtml(data, self.relpath(path))
+        elif mime[-4:] in {'+xml', '/xml'}:
+            data = self.parse_xml(data)
+        elif mime in OEB_STYLES:
+            data = self.parse_css(data, self.relpath(path))
+        elif mime in OEB_FONTS or path.rpartition('.')[-1].lower() in {'ttf', 'otf'}:
+            data = Sfnt(data)
+        return data
+
+    def parse_css(self, data, fname):
+        from cssutils import CSSParser, log
+        log.setLevel(logging.WARN)
+        log.raiseExceptions = False
+        data = self.decode(data)
+        data = self.css_preprocessor(data, add_namespace=False)
+        parser = CSSParser(loglevel=logging.WARNING,
+                           # We dont care about @import rules
+                           fetcher=lambda x: (None, None), log=_css_logger)
+        data = parser.parseString(data, href=fname, validate=False)
+        return data
+
+    def parsed(self, name):
+        ans = self.parsed_cache.get(name, None)
+        if ans is None:
+            mime = self.mime_map.get(name, guess_type(name)[0])
+            ans = self.parse(self.name_path_map[name], mime)
+            self.parsed_cache[name] = ans
+        return ans
+
+    @property
+    def opf(self):
+        return self.parsed(self.opf_name)
+
+    @property
+    def spine_items(self):
+        manifest_id_map = {item.get('id'):self.href_to_name(item.get('href'))
+            for item in self.opf.xpath('//opf:manifest/opf:item[@href and @id]',
+                namespaces={'opf':OPF2_NS})}
+
+        linear, non_linear = [], []
+        for item in self.opf.xpath('//opf:spine/opf:itemref[@idref]',
+                                   namespaces={'opf':OPF2_NS}):
+            idref = item.get('idref')
+            name = manifest_id_map.get(idref, None)
+            path = self.name_path_map.get(name, None)
+            if path:
+                if item.get('linear', 'yes') == 'yes':
+                    yield path
+                else:
+                    non_linear.append(path)
+        for path in non_linear:
+            yield path
+
+class InvalidEpub(InvalidBook):
+    pass
+
+OCF_NS = 'urn:oasis:names:tc:opendocument:xmlns:container'
+
+class EpubContainer(Container):
+
+    META_INF = {
+            'container.xml' : True,
+            'manifest.xml' : False,
+            'encryption.xml' : False,
+            'metadata.xml' : False,
+            'signatures.xml' : False,
+            'rights.xml' : False,
+    }
+
+    def __init__(self, pathtoepub, log):
+        self.pathtoepub = pathtoepub
+        tdir = self.root = PersistentTemporaryDirectory('_epub_container')
+        with open(self.pathtoepub, 'rb') as stream:
+            try:
+                zf = ZipFile(stream)
+                zf.extractall(tdir)
+            except:
+                log.exception('EPUB appears to be invalid ZIP file, trying a'
+                        ' more forgiving ZIP parser')
+                from calibre.utils.localunzip import extractall
+                stream.seek(0)
+                extractall(stream)
+        try:
+            os.remove(join(tdir, 'mimetype'))
+        except EnvironmentError:
+            pass
+
+        container_path = join(self.root, 'META-INF', 'container.xml')
+        if not exists(container_path):
+            raise InvalidEpub('No META-INF/container.xml in epub')
+        self.container = etree.fromstring(open(container_path, 'rb').read())
+        opf_files = self.container.xpath((
+            r'child::ocf:rootfiles/ocf:rootfile'
+            '[@media-type="%s" and @full-path]'%guess_type('a.opf')[0]
+            ), namespaces={'ocf':OCF_NS}
+        )
+        if not opf_files:
+            raise InvalidEpub('META-INF/container.xml contains no link to OPF file')
+        opf_path = os.path.join(self.root, *opf_files[0].get('full-path').split('/'))
+        if not exists(opf_path):
+            raise InvalidEpub('OPF file does not exist at location pointed to'
+                    ' by META-INF/container.xml')
+
+        super(EpubContainer, self).__init__(tdir, opf_path, log)
+
+        self.obfuscated_fonts = {}
+        if 'META-INF/encryption.xml' in self.name_path_map:
+            self.process_encryption()
+
+    def process_encryption(self):
+        fonts = {}
+        enc = self.parsed('META-INF/encryption.xml')
+        for em in enc.xpath('//*[local-name()="EncryptionMethod" and @Algorithm]'):
+            alg = em.get('Algorithm')
+            if alg not in {ADOBE_OBFUSCATION, IDPF_OBFUSCATION}:
+                raise DRMError()
+            cr = em.getparent().xpath('descendant::*[local-name()="CipherReference" and @URI]')[0]
+            name = self.href_to_name(cr.get('URI'), self.root)
+            path = self.name_path_map.get(name, None)
+            if path is not None:
+                fonts[name] = alg
+        if not fonts:
+            return
+
+        package_id = unique_identifier = idpf_key = None
+        for attrib, val in self.opf.attrib.iteritems():
+            if attrib.endswith('unique-identifier'):
+                package_id = val
+                break
+        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]
+                    break
+        if unique_identifier is not None:
+            idpf_key = hashlib.sha1(unique_identifier).digest()
+        key = None
+        for item in self.opf.xpath('//*[local-name()="metadata"]/*'
+                                   '[local-name()="identifier"]'):
+            scheme = None
+            for xkey in item.attrib.keys():
+                if xkey.endswith('scheme'):
+                    scheme = item.get(xkey)
+            if (scheme and scheme.lower() == 'uuid') or \
+                    (item.text and item.text.startswith('urn:uuid:')):
+                try:
+                    key = bytes(item.text).rpartition(':')[-1]
+                    key = uuid.UUID(key).bytes
+                except:
+                    self.log.exception('Failed to parse obfuscation key')
+                    key = None
+
+        for font, alg in fonts.iteritems():
+            path = self.name_path_map[font]
+            tkey = key if alg == ADOBE_OBFUSCATION else idpf_key
+            if not tkey:
+                raise InvalidBook('Failed to find obfuscation key')
+            decrypt_font(tkey, path, alg)
+            self.obfuscated_fonts[name] = (alg, tkey)
+
+class InvalidMobi(InvalidBook):
+    pass
+
+def do_explode(path, dest):
+    from calibre.ebooks.mobi.reader.mobi6 import MobiReader
+    from calibre.ebooks.mobi.reader.mobi8 import Mobi8Reader
+    with open(path, 'rb') as stream:
+        mr = MobiReader(stream, default_log, None, None)
+
+        with CurrentDir(dest):
+            mr = Mobi8Reader(mr, default_log)
+            opf = os.path.abspath(mr())
+            obfuscated_fonts = mr.encrypted_fonts
+            try:
+                os.remove('debug-raw.html')
+            except:
+                pass
+
+    return opf, obfuscated_fonts
+
+class AZW3Container(Container):
+
+    def __init__(self, pathtoazw3, log):
+        self.pathtoazw3 = pathtoazw3
+        tdir = self.root = PersistentTemporaryDirectory('_azw3_container')
+        with open(pathtoazw3, 'rb') as stream:
+            raw = stream.read(3)
+            if raw == b'TPZ':
+                raise InvalidMobi(_('This is not a MOBI file. It is a Topaz file.'))
+
+            try:
+                header = MetadataHeader(stream, default_log)
+            except MobiError:
+                raise InvalidMobi(_('This is not a MOBI file.'))
+
+            if header.encryption_type != 0:
+                raise DRMError()
+
+            kf8_type = header.kf8_type
+
+            if kf8_type is None:
+                raise InvalidMobi(_('This MOBI file does not contain a KF8 format '
+                        'book. KF8 is the new format from Amazon. calibre can '
+                        'only edit MOBI files that contain KF8 books. Older '
+                        'MOBI files without KF8 are not editable.'))
+
+            if kf8_type == 'joint':
+                raise InvalidMobi(_('This MOBI file contains both KF8 and '
+                    'older Mobi6 data. calibre can only edit MOBI files '
+                    'that contain only KF8 data.'))
+
+        try:
+            opf_path, obfuscated_fonts = fork_job(
+            'calibre.ebooks.oeb.polish.container', 'do_explode',
+            args=(pathtoazw3, tdir), no_output=True)['result']
+        except WorkerError as e:
+            log(e.orig_tb)
+            raise InvalidMobi('Failed to explode MOBI')
+        super(AZW3Container, self).__init__(tdir, opf_path, log)
+        self.obfuscated_fonts = {x.replace(os.sep, '/') for x in obfuscated_fonts}
+
+if __name__ == '__main__':
+    f = sys.argv[-1]
+    ebook = (AZW3Container if f.rpartition('.')[-1].lower() in {'azw3', 'mobi'}
+            else EpubContainer)(f, default_log)
+    for s in ebook.spine_items:
+        print (ebook.relpath(s))
+
diff --git a/src/calibre/ebooks/oeb/polish/errors.py b/src/calibre/ebooks/oeb/polish/errors.py
new file mode 100644
index 0000000000..0aa0f4993c
--- /dev/null
+++ b/src/calibre/ebooks/oeb/polish/errors.py
@@ -0,0 +1,18 @@
+#!/usr/bin/env python
+# vim:fileencoding=UTF-8:ts=4:sw=4:sta:et:sts=4:fdm=marker:ai
+from __future__ import (unicode_literals, division, absolute_import,
+                        print_function)
+
+__license__   = 'GPL v3'
+__copyright__ = '2013, Kovid Goyal <kovid at kovidgoyal.net>'
+__docformat__ = 'restructuredtext en'
+
+from calibre.ebooks import DRMError as _DRMError
+
+class InvalidBook(ValueError):
+    pass
+
+class DRMError(_DRMError):
+    def __init__(self):
+        super(DRMError, self).__init__(_('This file is locked with DRM. It cannot be edited.'))
+