315 lines
13 KiB
Python
315 lines
13 KiB
Python
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#!/usr/bin/env python3
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# -*- coding: utf-8 -*-
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# ineptepub.py
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# Copyright © 2009-2022 by i♥cabbages, Apprentice Harper et al.
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# Released under the terms of the GNU General Public Licence, version 3
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# <http://www.gnu.org/licenses/>
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"""
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Decrypt Adobe Digital Editions encrypted ePub books.
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"""
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KEYPATH = "adobekey.der"
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__license__ = 'GPL v3'
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__version__ = "8.0"
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import sys
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import os
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import traceback
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import base64
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import zlib
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import zipfile
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from zipfile import ZipInfo, ZipFile, ZIP_STORED, ZIP_DEFLATED
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from decrypt.zeroedzipinfo import ZeroedZipInfo
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from contextlib import closing
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from lxml import etree
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from uuid import UUID
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import hashlib
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try:
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from Cryptodome.Cipher import AES, PKCS1_v1_5
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from Cryptodome.PublicKey import RSA
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except ImportError:
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from Crypto.Cipher import AES, PKCS1_v1_5
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from Crypto.PublicKey import RSA
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def unpad(data, padding=16):
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if sys.version_info[0] == 2:
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pad_len = ord(data[-1])
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else:
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pad_len = data[-1]
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return data[:-pad_len]
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class ADEPTError(Exception):
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pass
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class ADEPTNewVersionError(Exception):
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pass
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META_NAMES = ('mimetype', 'META-INF/rights.xml')
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NSMAP = {'adept': 'http://ns.adobe.com/adept',
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'enc': 'http://www.w3.org/2001/04/xmlenc#'}
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class Decryptor(object):
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def __init__(self, bookkey, encryption):
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enc = lambda tag: '{%s}%s' % (NSMAP['enc'], tag)
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self._aes = AES.new(bookkey, AES.MODE_CBC, b'\x00'*16)
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self._encryption = etree.fromstring(encryption)
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self._encrypted = encrypted = set()
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self._encryptedForceNoDecomp = encryptedForceNoDecomp = set()
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self._otherData = otherData = set()
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self._json_elements_to_remove = json_elements_to_remove = set()
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self._has_remaining_xml = False
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expr = './%s/%s/%s' % (enc('EncryptedData'), enc('CipherData'),
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enc('CipherReference'))
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for elem in self._encryption.findall(expr):
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path = elem.get('URI', None)
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encryption_type_url = (elem.getparent().getparent().find("./%s" % (enc('EncryptionMethod'))).get('Algorithm', None))
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if path is not None:
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if (encryption_type_url == "http://www.w3.org/2001/04/xmlenc#aes128-cbc"):
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# Adobe
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path = path.encode('utf-8')
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encrypted.add(path)
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json_elements_to_remove.add(elem.getparent().getparent())
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elif (encryption_type_url == "http://ns.adobe.com/adept/xmlenc#aes128-cbc-uncompressed"):
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# Adobe uncompressed, for stuff like video files
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path = path.encode('utf-8')
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encryptedForceNoDecomp.add(path)
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json_elements_to_remove.add(elem.getparent().getparent())
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else:
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path = path.encode('utf-8')
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otherData.add(path)
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self._has_remaining_xml = True
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for elem in json_elements_to_remove:
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elem.getparent().remove(elem)
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def check_if_remaining(self):
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return self._has_remaining_xml
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def get_xml(self):
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return "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" + etree.tostring(self._encryption, encoding="utf-8", pretty_print=True, xml_declaration=False).decode("utf-8")
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def decompress(self, bytes):
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dc = zlib.decompressobj(-15)
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try:
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decompressed_bytes = dc.decompress(bytes)
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ex = dc.decompress(b'Z') + dc.flush()
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if ex:
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decompressed_bytes = decompressed_bytes + ex
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except:
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# possibly not compressed by zip - just return bytes
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return bytes
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return decompressed_bytes
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def decrypt(self, path, data):
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if path.encode('utf-8') in self._encrypted or path.encode('utf-8') in self._encryptedForceNoDecomp:
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data = self._aes.decrypt(data)[16:]
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if type(data[-1]) != int:
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place = ord(data[-1])
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else:
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place = data[-1]
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data = data[:-place]
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if not path.encode('utf-8') in self._encryptedForceNoDecomp:
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data = self.decompress(data)
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return data
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# check file to make check whether it's probably an Adobe Adept encrypted ePub
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def adeptBook(inpath):
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with closing(ZipFile(open(inpath, 'rb'))) as inf:
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namelist = set(inf.namelist())
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if 'META-INF/rights.xml' not in namelist or \
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'META-INF/encryption.xml' not in namelist:
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return False
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try:
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rights = etree.fromstring(inf.read('META-INF/rights.xml'))
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adept = lambda tag: '{%s}%s' % (NSMAP['adept'], tag)
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expr = './/%s' % (adept('encryptedKey'),)
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bookkey = ''.join(rights.findtext(expr))
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if len(bookkey) in [192, 172, 64]:
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return True
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except:
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# if we couldn't check, assume it is
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return True
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return False
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def isPassHashBook(inpath):
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# If this is an Adobe book, check if it's a PassHash-encrypted book (B&N)
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with closing(ZipFile(open(inpath, 'rb'))) as inf:
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namelist = set(inf.namelist())
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if 'META-INF/rights.xml' not in namelist or \
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'META-INF/encryption.xml' not in namelist:
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return False
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try:
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rights = etree.fromstring(inf.read('META-INF/rights.xml'))
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adept = lambda tag: '{%s}%s' % (NSMAP['adept'], tag)
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expr = './/%s' % (adept('encryptedKey'),)
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bookkey = ''.join(rights.findtext(expr))
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if len(bookkey) == 64:
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return True
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except:
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pass
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return False
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# Checks the license file and returns the UUID the book is licensed for.
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# This is used so that the Calibre plugin can pick the correct decryption key
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# first try without having to loop through all possible keys.
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def adeptGetUserUUID(inpath):
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with closing(ZipFile(open(inpath, 'rb'))) as inf:
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try:
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rights = etree.fromstring(inf.read('META-INF/rights.xml'))
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adept = lambda tag: '{%s}%s' % (NSMAP['adept'], tag)
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expr = './/%s' % (adept('user'),)
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user_uuid = ''.join(rights.findtext(expr))
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if user_uuid[:9] != "urn:uuid:":
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return None
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return user_uuid[9:]
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except:
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return None
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def removeHardening(rights, keytype, keydata):
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adept = lambda tag: '{%s}%s' % (NSMAP['adept'], tag)
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textGetter = lambda name: ''.join(rights.findtext('.//%s' % (adept(name),)))
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# Gather what we need, and generate the IV
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resourceuuid = UUID(textGetter("resource"))
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deviceuuid = UUID(textGetter("device"))
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fullfillmentuuid = UUID(textGetter("fulfillment")[:36])
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kekiv = UUID(int=resourceuuid.int ^ deviceuuid.int ^ fullfillmentuuid.int).bytes
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# Derive kek from just "keytype"
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rem = int(keytype, 10) % 16
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H = hashlib.sha256(keytype.encode("ascii")).digest()
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kek = H[2*rem : 16 + rem] + H[rem : 2*rem]
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return unpad(AES.new(kek, AES.MODE_CBC, kekiv).decrypt(keydata), 16) # PKCS#7
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def decryptBook(userkey, inpath, outpath):
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with closing(ZipFile(open(inpath, 'rb'))) as inf:
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namelist = inf.namelist()
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if 'META-INF/rights.xml' not in namelist or \
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'META-INF/encryption.xml' not in namelist:
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print("{0:s} is DRM-free.".format(os.path.basename(inpath)))
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return 1
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for name in META_NAMES:
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namelist.remove(name)
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try:
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rights = etree.fromstring(inf.read('META-INF/rights.xml'))
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adept = lambda tag: '{%s}%s' % (NSMAP['adept'], tag)
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expr = './/%s' % (adept('encryptedKey'),)
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bookkeyelem = rights.find(expr)
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bookkey = bookkeyelem.text
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keytype = bookkeyelem.attrib.get('keyType', '0')
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if len(bookkey) >= 172 and int(keytype, 10) > 2:
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print("{0:s} is a secure Adobe Adept ePub with hardening.".format(os.path.basename(inpath)))
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elif len(bookkey) == 172:
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print("{0:s} is a secure Adobe Adept ePub.".format(os.path.basename(inpath)))
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elif len(bookkey) == 64:
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print("{0:s} is a secure Adobe PassHash (B&N) ePub.".format(os.path.basename(inpath)))
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else:
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print("{0:s} is not an Adobe-protected ePub!".format(os.path.basename(inpath)))
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return 1
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if len(bookkey) != 64:
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# Normal or "hardened" Adobe ADEPT
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rsakey = RSA.importKey(userkey) # parses the ASN1 structure
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bookkey = base64.b64decode(bookkey)
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if int(keytype, 10) > 2:
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bookkey = removeHardening(rights, keytype, bookkey)
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try:
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bookkey = PKCS1_v1_5.new(rsakey).decrypt(bookkey, None) # automatically unpads
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except ValueError:
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bookkey = None
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if bookkey is None:
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print("Could not decrypt {0:s}. Wrong key".format(os.path.basename(inpath)))
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return 2
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else:
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# Adobe PassHash / B&N
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key = base64.b64decode(userkey)[:16]
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bookkey = base64.b64decode(bookkey)
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bookkey = unpad(AES.new(key, AES.MODE_CBC, b'\x00'*16).decrypt(bookkey), 16) # PKCS#7
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if len(bookkey) > 16:
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bookkey = bookkey[-16:]
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encryption = inf.read('META-INF/encryption.xml')
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decryptor = Decryptor(bookkey, encryption)
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kwds = dict(compression=ZIP_DEFLATED, allowZip64=False)
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with closing(ZipFile(open(outpath, 'wb'), 'w', **kwds)) as outf:
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for path in (["mimetype"] + namelist):
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data = inf.read(path)
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zi = ZipInfo(path)
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zi.compress_type=ZIP_DEFLATED
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if path == "mimetype":
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zi.compress_type = ZIP_STORED
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elif path == "META-INF/encryption.xml":
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# Check if there's still something in there
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if (decryptor.check_if_remaining()):
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data = decryptor.get_xml()
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print("Adding encryption.xml for the remaining embedded files.")
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# We removed DRM, but there's still stuff like obfuscated fonts.
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else:
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continue
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try:
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# get the file info, including time-stamp
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oldzi = inf.getinfo(path)
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# copy across useful fields
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zi.date_time = oldzi.date_time
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zi.comment = oldzi.comment
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zi.extra = oldzi.extra
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zi.internal_attr = oldzi.internal_attr
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# external attributes are dependent on the create system, so copy both.
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zi.external_attr = oldzi.external_attr
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zi.volume = oldzi.volume
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zi.create_system = oldzi.create_system
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zi.create_version = oldzi.create_version
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if any(ord(c) >= 128 for c in path) or any(ord(c) >= 128 for c in zi.comment):
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# If the file name or the comment contains any non-ASCII char, set the UTF8-flag
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zi.flag_bits |= 0x800
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except:
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pass
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# Python 3 has a bug where the external_attr is reset to `0o600 << 16`
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# if it's NULL, so we need a workaround:
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if zi.external_attr == 0:
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zi = ZeroedZipInfo(zi)
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if path == "META-INF/encryption.xml":
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outf.writestr(zi, data)
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else:
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outf.writestr(zi, decryptor.decrypt(path, data))
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except:
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print("Could not decrypt {0:s} because of an exception:\n{1:s}".format(os.path.basename(inpath), traceback.format_exc()))
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return 2
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return 0
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def decryptEPUB(inpath):
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keypath = KEYPATH
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outpath = os.path.basename(inpath).removesuffix(".epub") + "_decrypted.epub"
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userkey = open(keypath,'rb').read()
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result = decryptBook(userkey, inpath, outpath)
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if result == 0:
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print("Successfully decrypted")
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return outpath
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else:
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print("Decryption failed")
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return None
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