mirror of
https://github.com/noDRM/DeDRM_tools.git
synced 2024-11-17 03:16:09 +06:00
189 lines
5.6 KiB
Python
189 lines
5.6 KiB
Python
# This is a python script. You need a Python interpreter to run it.
|
|
# For example, ActiveState Python, which exists for windows.
|
|
#
|
|
# Changelog
|
|
# 0.01 - Initial version
|
|
# 0.02 - Huffdic compressed books were not properly decrypted
|
|
# 0.03 - Wasn't checking MOBI header length
|
|
# 0.04 - Wasn't sanity checking size of data record
|
|
# 0.05 - It seems that the extra data flags take two bytes not four
|
|
# 0.06 - And that low bit does mean something after all :-)
|
|
|
|
import sys,struct,binascii
|
|
|
|
class DrmException(Exception):
|
|
pass
|
|
|
|
#implementation of Pukall Cipher 1
|
|
def PC1(key, src, decryption=True):
|
|
sum1 = 0;
|
|
sum2 = 0;
|
|
keyXorVal = 0;
|
|
if len(key)!=16:
|
|
print "Bad key length!"
|
|
return None
|
|
wkey = []
|
|
for i in xrange(8):
|
|
wkey.append(ord(key[i*2])<<8 | ord(key[i*2+1]))
|
|
|
|
dst = ""
|
|
for i in xrange(len(src)):
|
|
temp1 = 0;
|
|
byteXorVal = 0;
|
|
for j in xrange(8):
|
|
temp1 ^= wkey[j]
|
|
sum2 = (sum2+j)*20021 + sum1
|
|
sum1 = (temp1*346)&0xFFFF
|
|
sum2 = (sum2+sum1)&0xFFFF
|
|
temp1 = (temp1*20021+1)&0xFFFF
|
|
byteXorVal ^= temp1 ^ sum2
|
|
curByte = ord(src[i])
|
|
if not decryption:
|
|
keyXorVal = curByte * 257;
|
|
curByte = ((curByte ^ (byteXorVal >> 8)) ^ byteXorVal) & 0xFF
|
|
if decryption:
|
|
keyXorVal = curByte * 257;
|
|
for j in xrange(8):
|
|
wkey[j] ^= keyXorVal;
|
|
dst+=chr(curByte)
|
|
return dst
|
|
|
|
def checksumPid(s):
|
|
letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ123456789"
|
|
crc = (~binascii.crc32(s,-1))&0xFFFFFFFF
|
|
crc = crc ^ (crc >> 16)
|
|
res = s
|
|
l = len(letters)
|
|
for i in (0,1):
|
|
b = crc & 0xff
|
|
pos = (b // l) ^ (b % l)
|
|
res += letters[pos%l]
|
|
crc >>= 8
|
|
return res
|
|
|
|
def getSizeOfTrailingDataEntries(ptr, size, flags):
|
|
def getSizeOfTrailingDataEntry(ptr, size):
|
|
bitpos, result = 0, 0
|
|
if size <= 0:
|
|
return result
|
|
while True:
|
|
v = ord(ptr[size-1])
|
|
result |= (v & 0x7F) << bitpos
|
|
bitpos += 7
|
|
size -= 1
|
|
if (v & 0x80) != 0 or (bitpos >= 28) or (size == 0):
|
|
return result
|
|
num = 0
|
|
testflags = flags >> 1
|
|
while testflags:
|
|
if testflags & 1:
|
|
num += getSizeOfTrailingDataEntry(ptr, size - num)
|
|
testflags >>= 1
|
|
if flags & 1:
|
|
num += (ord(ptr[size - num - 1]) & 0x3) + 1
|
|
return num
|
|
|
|
class DrmStripper:
|
|
def loadSection(self, section):
|
|
if (section + 1 == self.num_sections):
|
|
endoff = len(self.data_file)
|
|
else:
|
|
endoff = self.sections[section + 1][0]
|
|
off = self.sections[section][0]
|
|
return self.data_file[off:endoff]
|
|
|
|
def patch(self, off, new):
|
|
self.data_file = self.data_file[:off] + new + self.data_file[off+len(new):]
|
|
|
|
def patchSection(self, section, new, in_off = 0):
|
|
if (section + 1 == self.num_sections):
|
|
endoff = len(self.data_file)
|
|
else:
|
|
endoff = self.sections[section + 1][0]
|
|
off = self.sections[section][0]
|
|
assert off + in_off + len(new) <= endoff
|
|
self.patch(off + in_off, new)
|
|
|
|
def parseDRM(self, data, count, pid):
|
|
pid = pid.ljust(16,'\0')
|
|
keyvec1 = "\x72\x38\x33\xB0\xB4\xF2\xE3\xCA\xDF\x09\x01\xD6\xE2\xE0\x3F\x96"
|
|
temp_key = PC1(keyvec1, pid, False)
|
|
temp_key_sum = sum(map(ord,temp_key)) & 0xff
|
|
found_key = None
|
|
for i in xrange(count):
|
|
verification, size, type, cksum, cookie = struct.unpack('>LLLBxxx32s', data[i*0x30:i*0x30+0x30])
|
|
cookie = PC1(temp_key, cookie)
|
|
ver,flags,finalkey,expiry,expiry2 = struct.unpack('>LL16sLL', cookie)
|
|
if verification == ver and cksum == temp_key_sum and (flags & 0x1F) == 1:
|
|
found_key = finalkey
|
|
break
|
|
return found_key
|
|
|
|
|
|
def __init__(self, data_file, pid):
|
|
|
|
if checksumPid(pid[0:-2]) != pid:
|
|
raise DrmException("invalid PID checksum")
|
|
pid = pid[0:-2]
|
|
|
|
self.data_file = data_file
|
|
header = data_file[0:72]
|
|
if header[0x3C:0x3C+8] != 'BOOKMOBI':
|
|
raise DrmException("invalid file format")
|
|
self.num_sections, = struct.unpack('>H', data_file[76:78])
|
|
|
|
self.sections = []
|
|
for i in xrange(self.num_sections):
|
|
offset, a1,a2,a3,a4 = struct.unpack('>LBBBB', data_file[78+i*8:78+i*8+8])
|
|
flags, val = a1, a2<<16|a3<<8|a4
|
|
self.sections.append( (offset, flags, val) )
|
|
|
|
sect = self.loadSection(0)
|
|
records, = struct.unpack('>H', sect[0x8:0x8+2])
|
|
mobi_length, = struct.unpack('>L',sect[0x14:0x18])
|
|
extra_data_flags = 0
|
|
if mobi_length >= 0xE4:
|
|
extra_data_flags, = struct.unpack('>H', sect[0xF2:0xF4])
|
|
|
|
|
|
crypto_type, = struct.unpack('>H', sect[0xC:0xC+2])
|
|
if crypto_type != 2:
|
|
raise DrmException("invalid encryption type: %d" % crypto_type)
|
|
|
|
# calculate the keys
|
|
drm_ptr, drm_count, drm_size, drm_flags = struct.unpack('>LLLL', sect[0xA8:0xA8+16])
|
|
found_key = self.parseDRM(sect[drm_ptr:drm_ptr+drm_size], drm_count, pid)
|
|
if not found_key:
|
|
raise DrmException("no key found. maybe the PID is incorrect")
|
|
|
|
# kill the drm keys
|
|
self.patchSection(0, "\0" * drm_size, drm_ptr)
|
|
# kill the drm pointers
|
|
self.patchSection(0, "\xff" * 4 + "\0" * 12, 0xA8)
|
|
# clear the crypto type
|
|
self.patchSection(0, "\0" * 2, 0xC)
|
|
|
|
# decrypt sections
|
|
print "Decrypting. Please wait...",
|
|
for i in xrange(1, records+1):
|
|
data = self.loadSection(i)
|
|
extra_size = getSizeOfTrailingDataEntries(data, len(data), extra_data_flags)
|
|
self.patchSection(i, PC1(found_key, data[0:len(data) - extra_size]))
|
|
print "done"
|
|
def getResult(self):
|
|
return self.data_file
|
|
|
|
print "MobiDeDrm v0.06. Copyright (c) 2008 The Dark Reverser"
|
|
if len(sys.argv)<4:
|
|
print "Removes protection from Mobipocket books"
|
|
print "Usage:"
|
|
print " mobidedrm infile.mobi outfile.mobi PID"
|
|
else:
|
|
infile = sys.argv[1]
|
|
outfile = sys.argv[2]
|
|
pid = sys.argv[3]
|
|
data_file = file(infile, 'rb').read()
|
|
try:
|
|
file(outfile, 'wb').write(DrmStripper(data_file, pid).getResult())
|
|
except DrmException, e:
|
|
print "Error: %s" % e |