usr bin python This is python script You need Python interpreter to ru

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#!/usr/bin/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
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
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
flags >>= 1
while flags:
if flags & 1:
num += getSizeOfTrailingDataEntry(ptr, size - num)
flags >>= 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])
extra_data_flags, = struct.unpack('>L', sect[0xF0:0xF4])
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 v0.02. 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