def decrypt(self, content):
length = len(content)
extra = length & 0x7
if extra > 0:
self.warn("content length not a multiple of block size")
content += b"\0" * (8 - extra)
msdes.deskey(self.bookkey, msdes.DE1)
return msdes.des(content)
def _build_drm_storage(self):
drmsource = 'Free as in freedom\0'.encode('utf-16-le')
self._add_file('/DRMStorage/DRMSource', drmsource)
tempkey = self._calculate_deskey([self._meta, drmsource])
msdes.deskey(tempkey, msdes.EN0)
self._add_file('/DRMStorage/DRMSealed', msdes.des(b"\0" * 16))
self._bookkey = b'\0' * 8
self._add_file('/DRMStorage/ValidationStream', b'MSReader', 3)
def _build_storage(self):
mapping = [
(1, 'MSCompressed', (LZXCOMPRESS_GUID, )),
(2, 'EbEncryptDS', (LZXCOMPRESS_GUID, DESENCRYPT_GUID)),
(3, 'EbEncryptOnlyDS', (DESENCRYPT_GUID, )),
]
for secnum, name, transforms in mapping:
root = '::DataSpace/Storage/' + name
data = self._sections[secnum].getvalue()
cdata, sdata, tdata, rdata = b'', b'', b'', b''
for guid in transforms:
tdata = packguid(guid) + tdata
sdata = sdata + pack('<Q', len(data))
if guid == DESENCRYPT_GUID:
cdata = MSDES_CONTROL + cdata
if not data:
continue
msdes.deskey(self._bookkey, msdes.EN0)
pad = 8 - (len(data) & 0x7)
if pad != 8:
data = data + (b'\0' * pad)
data = msdes.des(data)
elif guid == LZXCOMPRESS_GUID:
cdata = LZXC_CONTROL + cdata
if not data:
continue
unlen = len(data)
lzx = Compressor(17)
data, rtable = lzx.compress(data, flush=True)
rdata = io.BytesIO()
rdata.write(
pack('<IIIIQQQQ', 3, len(rtable), 8, 0x28, unlen,
len(data), 0x8000, 0))
for uncomp, comp in rtable[:-1]:
rdata.write(pack('<Q', comp))
rdata = rdata.getvalue()
self._add_file(root + '/Content', data)
self._add_file(root + '/ControlData', cdata)
self._add_file(root + '/SpanInfo', sdata)
self._add_file(root + '/Transform/List', tdata)
troot = root + '/Transform'
for guid in transforms:
dname = self._djoin(troot, guid, 'InstanceData')
self._add_folder(dname)
if guid == LZXCOMPRESS_GUID:
dname += '/ResetTable'
self._add_file(dname, rdata)
def read_drm(self):
self.drmlevel = 0
if '/DRMStorage/Licenses/EUL' in self.entries:
self.drmlevel = 5
elif '/DRMStorage/DRMBookplate' in self.entries:
self.drmlevel = 3
elif '/DRMStorage/DRMSealed' in self.entries:
self.drmlevel = 1
else:
return
if self.drmlevel < 5:
msdes.deskey(self.calculate_deskey(), msdes.DE1)
bookkey = msdes.des(self.get_file('/DRMStorage/DRMSealed'))
if bookkey[0:1] != b'\0':
raise LitError('Unable to decrypt title key!')
self.bookkey = bookkey[1:9]
else:
raise DRMError("Cannot access DRM-protected book")