mirror of
https://github.com/noDRM/DeDRM_tools.git
synced 2024-11-05 13:36:10 +06:00
150 lines
4.4 KiB
Python
150 lines
4.4 KiB
Python
import sys,struct,binascii
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class DrmException(Exception):
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pass
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#implementation of Pukall Cipher 1
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def PC1(key, src, decryption=True):
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sum1 = 0;
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sum2 = 0;
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keyXorVal = 0;
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if len(key)!=16:
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print "Bad key length!"
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return None
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wkey = []
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for i in xrange(8):
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wkey.append(ord(key[i*2])<<8 | ord(key[i*2+1]))
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dst = ""
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for i in xrange(len(src)):
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temp1 = 0;
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byteXorVal = 0;
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for j in xrange(8):
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temp1 ^= wkey[j]
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sum2 = (sum2+j)*20021 + sum1
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sum1 = (temp1*346)&0xFFFF
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sum2 = (sum2+sum1)&0xFFFF
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temp1 = (temp1*20021+1)&0xFFFF
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byteXorVal ^= temp1 ^ sum2
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curByte = ord(src[i])
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if not decryption:
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keyXorVal = curByte * 257;
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curByte = ((curByte ^ (byteXorVal >> 8)) ^ byteXorVal) & 0xFF
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if decryption:
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keyXorVal = curByte * 257;
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for j in xrange(8):
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wkey[j] ^= keyXorVal;
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dst+=chr(curByte)
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return dst
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def checksumPid(s):
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letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ123456789"
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crc = (~binascii.crc32(s,-1))&0xFFFFFFFF
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crc = crc ^ (crc >> 16)
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res = s
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l = len(letters)
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for i in (0,1):
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b = crc & 0xff
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pos = (b // l) ^ (b % l)
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res += letters[pos%l]
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crc >>= 8
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return res
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class DrmStripper:
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def loadSection(self, section):
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if (section + 1 == self.num_sections):
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endoff = len(self.data_file)
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else:
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endoff = self.sections[section + 1][0]
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off = self.sections[section][0]
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return self.data_file[off:endoff]
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def patch(self, off, new):
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self.data_file = self.data_file[:off] + new + self.data_file[off+len(new):]
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def patchSection(self, section, new, in_off = 0):
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if (section + 1 == self.num_sections):
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endoff = len(self.data_file)
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else:
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endoff = self.sections[section + 1][0]
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off = self.sections[section][0]
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assert off + in_off + len(new) <= endoff
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self.patch(off + in_off, new)
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def parseDRM(self, data, count, pid):
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pid = pid.ljust(16,'\0')
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keyvec1 = "\x72\x38\x33\xB0\xB4\xF2\xE3\xCA\xDF\x09\x01\xD6\xE2\xE0\x3F\x96"
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temp_key = PC1(keyvec1, pid, False)
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temp_key_sum = sum(map(ord,temp_key)) & 0xff
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found_key = None
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for i in xrange(count):
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verification, size, type, cksum, cookie = struct.unpack('>LLLBxxx32s', data[i*0x30:i*0x30+0x30])
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cookie = PC1(temp_key, cookie)
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ver,flags,finalkey,expiry,expiry2 = struct.unpack('>LL16sLL', cookie)
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if verification == ver and cksum == temp_key_sum and (flags & 0x1F) == 1:
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found_key = finalkey
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break
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return found_key
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def __init__(self, data_file, pid):
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if checksumPid(pid[0:-2]) != pid:
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raise DrmException("invalid PID checksum")
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pid = pid[0:-2]
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self.data_file = data_file
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header = data_file[0:72]
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if header[0x3C:0x3C+8] != 'BOOKMOBI':
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raise DrmException("invalid file format")
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self.num_sections, = struct.unpack('>H', data_file[76:78])
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self.sections = []
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for i in xrange(self.num_sections):
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offset, a1,a2,a3,a4 = struct.unpack('>LBBBB', data_file[78+i*8:78+i*8+8])
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flags, val = a1, a2<<16|a3<<8|a4
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self.sections.append( (offset, flags, val) )
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sect = self.loadSection(0)
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records, = struct.unpack('>H', sect[0x8:0x8+2])
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crypto_type, = struct.unpack('>H', sect[0xC:0xC+2])
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if crypto_type != 2:
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raise DrmException("invalid encryption type: %d" % crypto_type)
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# calculate the keys
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drm_ptr, drm_count, drm_size, drm_flags = struct.unpack('>LLLL', sect[0xA8:0xA8+16])
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found_key = self.parseDRM(sect[drm_ptr:drm_ptr+drm_size], drm_count, pid)
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if not found_key:
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raise DrmException("no key found. maybe the PID is incorrect")
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# kill the drm keys
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self.patchSection(0, "\0" * drm_size, drm_ptr)
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# kill the drm pointers
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self.patchSection(0, "\xff" * 4 + "\0" * 12, 0xA8)
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# clear the crypto type
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self.patchSection(0, "\0" * 2, 0xC)
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# decrypt sections
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print "Decrypting. Please wait...",
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for i in xrange(1, records+1):
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self.patchSection(i, PC1(found_key, self.loadSection(i)))
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print "done"
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def getResult(self):
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return self.data_file
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print "MobiDeDrm v0.01. Copyright (c) 2008 The Dark Reverser"
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if len(sys.argv)<4:
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print "Removes protection from Mobipocket books"
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print "Usage: mobidedrm infile.mobi outfile.mobi PID"
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else:
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infile = sys.argv[1]
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outfile = sys.argv[2]
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pid = sys.argv[3]
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data_file = file(infile, 'rb').read()
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try:
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file(outfile, 'wb').write(DrmStripper(data_file, pid).getResult())
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except DrmException, e:
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print "Error: %s" % e |