480 lines
18 KiB
Python
480 lines
18 KiB
Python
#! /usr/bin/python
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# ineptepub_plugin.py
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# Released under the terms of the GNU General Public Licence, version 3 or
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# later. <http://www.gnu.org/licenses/>
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#
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# Requires Calibre version 0.6.44 or higher.
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#
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# All credit given to I <3 Cabbages for the original standalone scripts.
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# I had the much easier job of converting them to a Calibre plugin.
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#
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# This plugin is meant to decrypt Adobe Digital Edition Epubs that are protected
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# with Adobe's Adept encryption. It is meant to function without having to install
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# any dependencies... other than having Calibre installed, of course. It will still
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# work if you have Python and PyCrypto already installed, but they aren't necessary.
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#
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# Configuration:
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# When first run, the plugin will attempt to find your Adobe Digital Editions installation
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# (on Windows and Mac OS's). If successful, it will create an 'adeptkey.der' file and
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# save it in Calibre's configuration directory. It will use that file on subsequent runs.
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# If there are already '*.der' files in the directory, the plugin won't attempt to
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# find the ADE installation. So if you have ADE installed on the same machine as Calibre...
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# you are ready to go.
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#
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# If you already have keyfiles generated with I <3 Cabbages' ineptkey.pyw script,
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# you can put those keyfiles in Calibre's configuration directory. The easiest
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# way to find the correct directory is to go to Calibre's Preferences page... click
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# on the 'Miscellaneous' button (looks like a gear), and then click the 'Open Calibre
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# configuration directory' button. Paste your keyfiles in there. Just make sure that
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# they have different names and are saved with the '.der' extension (like the ineptkey
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# script produces). This directory isn't touched when upgrading Calibre, so it's quite
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# safe to leave them there.
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#
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# Since there is no Linux version of Adobe Digital Editions, Linux users will have to
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# obtain a keyfile through other methods and put the file in Calibre's configuration directory.
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#
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# All keyfiles with a '.der' extension found in Calibre's configuration directory will
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# be used to attempt to decrypt a book.
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#
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# ** NOTE ** There is no plugin customization data for the Inept Epub DeDRM plugin.
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#
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# Revision history:
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# 0.1 - Initial release
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# 0.1.1 - Allow Windows users to make use of openssl if they have it installed.
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# - Incorporated SomeUpdates zipfix routine.
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# 0.1.2 - Removed Carbon dependency for Mac users. Fixes an issue that was a
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# result of Calibre changing to python 2.7.
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# 0.1.3 - bug fix for epubs with non-ascii chars in file names
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# 0.1.4 - default to try PyCrypto first on Windows
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# 0.1.5 - update zipfix to handle out of position mimetypes
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# 0.1.6 - update zipfix to handle completely missing mimetype files
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"""
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Decrypt Adobe ADEPT-encrypted EPUB books.
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"""
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from __future__ import with_statement
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__license__ = 'GPL v3'
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import sys
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import os
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import zlib
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import zipfile
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import re
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from zipfile import ZipFile, ZIP_STORED, ZIP_DEFLATED
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from contextlib import closing
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import xml.etree.ElementTree as etree
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global AES
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global RSA
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META_NAMES = ('mimetype', 'META-INF/rights.xml', 'META-INF/encryption.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 ADEPTError(Exception):
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pass
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def _load_crypto_libcrypto():
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from ctypes import CDLL, POINTER, c_void_p, c_char_p, c_int, c_long, \
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Structure, c_ulong, create_string_buffer, cast
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from ctypes.util import find_library
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if sys.platform.startswith('win'):
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libcrypto = find_library('libeay32')
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else:
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libcrypto = find_library('crypto')
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if libcrypto is None:
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raise ADEPTError('libcrypto not found')
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libcrypto = CDLL(libcrypto)
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RSA_NO_PADDING = 3
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AES_MAXNR = 14
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c_char_pp = POINTER(c_char_p)
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c_int_p = POINTER(c_int)
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class RSA(Structure):
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pass
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RSA_p = POINTER(RSA)
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class AES_KEY(Structure):
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_fields_ = [('rd_key', c_long * (4 * (AES_MAXNR + 1))),
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('rounds', c_int)]
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AES_KEY_p = POINTER(AES_KEY)
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def F(restype, name, argtypes):
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func = getattr(libcrypto, name)
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func.restype = restype
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func.argtypes = argtypes
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return func
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d2i_RSAPrivateKey = F(RSA_p, 'd2i_RSAPrivateKey',
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[RSA_p, c_char_pp, c_long])
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RSA_size = F(c_int, 'RSA_size', [RSA_p])
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RSA_private_decrypt = F(c_int, 'RSA_private_decrypt',
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[c_int, c_char_p, c_char_p, RSA_p, c_int])
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RSA_free = F(None, 'RSA_free', [RSA_p])
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AES_set_decrypt_key = F(c_int, 'AES_set_decrypt_key',
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[c_char_p, c_int, AES_KEY_p])
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AES_cbc_encrypt = F(None, 'AES_cbc_encrypt',
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[c_char_p, c_char_p, c_ulong, AES_KEY_p, c_char_p,
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c_int])
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class RSA(object):
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def __init__(self, der):
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buf = create_string_buffer(der)
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pp = c_char_pp(cast(buf, c_char_p))
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rsa = self._rsa = d2i_RSAPrivateKey(None, pp, len(der))
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if rsa is None:
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raise ADEPTError('Error parsing ADEPT user key DER')
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def decrypt(self, from_):
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rsa = self._rsa
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to = create_string_buffer(RSA_size(rsa))
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dlen = RSA_private_decrypt(len(from_), from_, to, rsa,
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RSA_NO_PADDING)
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if dlen < 0:
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raise ADEPTError('RSA decryption failed')
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return to[:dlen]
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def __del__(self):
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if self._rsa is not None:
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RSA_free(self._rsa)
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self._rsa = None
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class AES(object):
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def __init__(self, userkey):
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self._blocksize = len(userkey)
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if (self._blocksize != 16) and (self._blocksize != 24) and (self._blocksize != 32) :
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raise ADEPTError('AES improper key used')
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return
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key = self._key = AES_KEY()
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rv = AES_set_decrypt_key(userkey, len(userkey) * 8, key)
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if rv < 0:
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raise ADEPTError('Failed to initialize AES key')
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def decrypt(self, data):
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out = create_string_buffer(len(data))
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iv = ("\x00" * self._blocksize)
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rv = AES_cbc_encrypt(data, out, len(data), self._key, iv, 0)
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if rv == 0:
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raise ADEPTError('AES decryption failed')
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return out.raw
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print 'IneptEpub: Using libcrypto.'
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return (AES, RSA)
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def _load_crypto_pycrypto():
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from Crypto.Cipher import AES as _AES
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from Crypto.PublicKey import RSA as _RSA
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# ASN.1 parsing code from tlslite
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class ASN1Error(Exception):
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pass
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class ASN1Parser(object):
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class Parser(object):
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def __init__(self, bytes):
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self.bytes = bytes
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self.index = 0
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def get(self, length):
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if self.index + length > len(self.bytes):
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raise ASN1Error("Error decoding ASN.1")
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x = 0
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for count in range(length):
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x <<= 8
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x |= self.bytes[self.index]
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self.index += 1
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return x
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def getFixBytes(self, lengthBytes):
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bytes = self.bytes[self.index : self.index+lengthBytes]
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self.index += lengthBytes
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return bytes
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def getVarBytes(self, lengthLength):
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lengthBytes = self.get(lengthLength)
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return self.getFixBytes(lengthBytes)
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def getFixList(self, length, lengthList):
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l = [0] * lengthList
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for x in range(lengthList):
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l[x] = self.get(length)
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return l
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def getVarList(self, length, lengthLength):
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lengthList = self.get(lengthLength)
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if lengthList % length != 0:
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raise ASN1Error("Error decoding ASN.1")
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lengthList = int(lengthList/length)
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l = [0] * lengthList
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for x in range(lengthList):
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l[x] = self.get(length)
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return l
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def startLengthCheck(self, lengthLength):
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self.lengthCheck = self.get(lengthLength)
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self.indexCheck = self.index
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def setLengthCheck(self, length):
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self.lengthCheck = length
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self.indexCheck = self.index
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def stopLengthCheck(self):
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if (self.index - self.indexCheck) != self.lengthCheck:
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raise ASN1Error("Error decoding ASN.1")
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def atLengthCheck(self):
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if (self.index - self.indexCheck) < self.lengthCheck:
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return False
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elif (self.index - self.indexCheck) == self.lengthCheck:
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return True
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else:
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raise ASN1Error("Error decoding ASN.1")
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def __init__(self, bytes):
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p = self.Parser(bytes)
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p.get(1)
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self.length = self._getASN1Length(p)
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self.value = p.getFixBytes(self.length)
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def getChild(self, which):
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p = self.Parser(self.value)
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for x in range(which+1):
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markIndex = p.index
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p.get(1)
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length = self._getASN1Length(p)
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p.getFixBytes(length)
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return ASN1Parser(p.bytes[markIndex:p.index])
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def _getASN1Length(self, p):
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firstLength = p.get(1)
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if firstLength<=127:
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return firstLength
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else:
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lengthLength = firstLength & 0x7F
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return p.get(lengthLength)
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class AES(object):
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def __init__(self, key):
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self._aes = _AES.new(key, _AES.MODE_CBC)
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def decrypt(self, data):
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return self._aes.decrypt(data)
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class RSA(object):
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def __init__(self, der):
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key = ASN1Parser([ord(x) for x in der])
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key = [key.getChild(x).value for x in xrange(1, 4)]
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key = [self.bytesToNumber(v) for v in key]
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self._rsa = _RSA.construct(key)
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def bytesToNumber(self, bytes):
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total = 0L
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for byte in bytes:
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total = (total << 8) + byte
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return total
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def decrypt(self, data):
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return self._rsa.decrypt(data)
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print 'IneptEpub: Using pycrypto.'
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return (AES, RSA)
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def _load_crypto():
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_aes = _rsa = None
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cryptolist = (_load_crypto_libcrypto, _load_crypto_pycrypto)
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if sys.platform.startswith('win'):
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cryptolist = (_load_crypto_pycrypto, _load_crypto_libcrypto)
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for loader in cryptolist:
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try:
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_aes, _rsa = loader()
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break
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except (ImportError, ADEPTError):
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pass
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return (_aes, _rsa)
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class ZipInfo(zipfile.ZipInfo):
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def __init__(self, *args, **kwargs):
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if 'compress_type' in kwargs:
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compress_type = kwargs.pop('compress_type')
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super(ZipInfo, self).__init__(*args, **kwargs)
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self.compress_type = compress_type
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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(bookkey)
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encryption = etree.fromstring(encryption)
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self._encrypted = encrypted = set()
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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 encryption.findall(expr):
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path = elem.get('URI', None)
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path = path.encode('utf-8')
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if path is not None:
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encrypted.add(path)
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def decompress(self, bytes):
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dc = zlib.decompressobj(-15)
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bytes = dc.decompress(bytes)
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ex = dc.decompress('Z') + dc.flush()
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if ex:
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bytes = bytes + ex
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return bytes
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def decrypt(self, path, data):
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if path in self._encrypted:
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data = self._aes.decrypt(data)[16:]
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data = data[:-ord(data[-1])]
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data = self.decompress(data)
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return data
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def plugin_main(userkey, inpath, outpath):
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rsa = RSA(userkey)
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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 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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bookkey = ''.join(rights.findtext(expr))
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bookkey = rsa.decrypt(bookkey.decode('base64'))
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# Padded as per RSAES-PKCS1-v1_5
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if bookkey[-17] != '\x00':
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raise ADEPTError('problem decrypting session key')
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encryption = inf.read('META-INF/encryption.xml')
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decryptor = Decryptor(bookkey[-16:], 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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zi = ZipInfo('mimetype', compress_type=ZIP_STORED)
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outf.writestr(zi, inf.read('mimetype'))
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for path in namelist:
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data = inf.read(path)
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outf.writestr(path, decryptor.decrypt(path, data))
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except:
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return 2
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return 0
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from calibre.customize import FileTypePlugin
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class IneptDeDRM(FileTypePlugin):
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name = 'Inept Epub DeDRM'
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description = 'Removes DRM from secure Adobe epub files. \
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Credit given to I <3 Cabbages for the original stand-alone scripts.'
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supported_platforms = ['linux', 'osx', 'windows']
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author = 'DiapDealer'
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version = (0, 1, 6)
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minimum_calibre_version = (0, 6, 44) # Compiled python libraries cannot be imported in earlier versions.
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file_types = set(['epub'])
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on_import = True
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priority = 100
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def run(self, path_to_ebook):
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global AES
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global RSA
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from calibre.gui2 import is_ok_to_use_qt
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from PyQt4.Qt import QMessageBox
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from calibre.constants import iswindows, isosx
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AES, RSA = _load_crypto()
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if AES == None or RSA == None:
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# Failed to load libcrypto or PyCrypto... Adobe Epubs can\'t be decrypted.'
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raise ADEPTError('IneptEpub: Failed to load crypto libs... Adobe Epubs can\'t be decrypted.')
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return
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# Load any keyfiles (*.der) included Calibre's config directory.
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userkeys = []
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# Find Calibre's configuration directory.
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confpath = os.path.split(os.path.split(self.plugin_path)[0])[0]
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print 'IneptEpub: Calibre configuration directory = %s' % confpath
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files = os.listdir(confpath)
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filefilter = re.compile("\.der$", re.IGNORECASE)
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files = filter(filefilter.search, files)
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if files:
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try:
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for filename in files:
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fpath = os.path.join(confpath, filename)
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with open(fpath, 'rb') as f:
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userkeys.append(f.read())
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print 'IneptEpub: Keyfile %s found in config folder.' % filename
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except IOError:
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print 'IneptEpub: Error reading keyfiles from config directory.'
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pass
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else:
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# Try to find key from ADE install and save the key in
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# Calibre's configuration directory for future use.
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if iswindows or isosx:
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# ADE key retrieval script included in respective OS folder.
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from ade_key import retrieve_key
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try:
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keydata = retrieve_key()
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userkeys.append(keydata)
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keypath = os.path.join(confpath, 'calibre-adeptkey.der')
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with open(keypath, 'wb') as f:
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f.write(keydata)
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print 'IneptEpub: Created keyfile from ADE install.'
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except:
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print 'IneptEpub: Couldn\'t Retrieve key from ADE install.'
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pass
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if not userkeys:
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# No user keys found... bail out.
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raise ADEPTError('IneptEpub - No keys found. Check keyfile(s)/ADE install')
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return
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# Attempt to decrypt epub with each encryption key found.
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for userkey in userkeys:
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# Create a TemporaryPersistent file to work with.
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# Check original epub archive for zip errors.
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import zipfix
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inf = self.temporary_file('.epub')
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try:
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fr = zipfix.fixZip(path_to_ebook, inf.name)
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fr.fix()
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except Exception, e:
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raise Exception(e)
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return
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of = self.temporary_file('.epub')
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# Give the user key, ebook and TemporaryPersistent file to the plugin_main function.
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result = plugin_main(userkey, inf.name, of.name)
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# Ebook is not an Adobe Adept epub... do nothing and pass it on.
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# This allows a non-encrypted epub to be imported without error messages.
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if result == 1:
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print 'IneptEpub: Not an Adobe Adept Epub... punting.'
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of.close()
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return path_to_ebook
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break
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# Decryption was successful return the modified PersistentTemporary
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# file to Calibre's import process.
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if result == 0:
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print 'IneptEpub: Encryption successfully removed.'
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of.close
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return of.name
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break
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print 'IneptEpub: Encryption key invalid... trying others.'
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of.close()
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# Something went wrong with decryption.
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# Import the original unmolested epub.
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of.close
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raise ADEPTError('IneptEpub - Ultimately failed to decrypt')
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return
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