DeDRM_tools/KindleBooks/lib/k4mutils.py

# standlone set of Mac OSX specific routines needed for K4DeDRM

from __future__ import with_statement

import sys
import os
import subprocess

from struct import pack, unpack, unpack_from

class DrmException(Exception):
    pass


# interface to needed routines in openssl's libcrypto
def _load_crypto_libcrypto():
    from ctypes import CDLL, byref, POINTER, c_void_p, c_char_p, c_int, c_long, \
        Structure, c_ulong, create_string_buffer, addressof, string_at, cast
    from ctypes.util import find_library

    libcrypto = find_library('crypto')
    if libcrypto is None:
        raise DrmException('libcrypto not found')
    libcrypto = CDLL(libcrypto)

    AES_MAXNR = 14
    c_char_pp = POINTER(c_char_p)
    c_int_p = POINTER(c_int)

    class AES_KEY(Structure):
        _fields_ = [('rd_key', c_long * (4 * (AES_MAXNR + 1))), ('rounds', c_int)]
    AES_KEY_p = POINTER(AES_KEY)
    
    def F(restype, name, argtypes):
        func = getattr(libcrypto, name)
        func.restype = restype
        func.argtypes = argtypes
        return func
    
    AES_cbc_encrypt = F(None, 'AES_cbc_encrypt',[c_char_p, c_char_p, c_ulong, AES_KEY_p, c_char_p,c_int])

    AES_set_decrypt_key = F(c_int, 'AES_set_decrypt_key',[c_char_p, c_int, AES_KEY_p])

    PKCS5_PBKDF2_HMAC_SHA1 = F(c_int, 'PKCS5_PBKDF2_HMAC_SHA1', 
                                [c_char_p, c_ulong, c_char_p, c_ulong, c_ulong, c_ulong, c_char_p])
    
    class LibCrypto(object):
        def __init__(self):
            self._blocksize = 0
            self._keyctx = None
            self.iv = 0

        def set_decrypt_key(self, userkey, iv):
            self._blocksize = len(userkey)
            if (self._blocksize != 16) and (self._blocksize != 24) and (self._blocksize != 32) :
                raise DrmException('AES improper key used')
                return
            keyctx = self._keyctx = AES_KEY()
            self.iv = iv
            rv = AES_set_decrypt_key(userkey, len(userkey) * 8, keyctx)
            if rv < 0:
                raise DrmException('Failed to initialize AES key')

        def decrypt(self, data):
            out = create_string_buffer(len(data))
            rv = AES_cbc_encrypt(data, out, len(data), self._keyctx, self.iv, 0)
            if rv == 0:
                raise DrmException('AES decryption failed')
            return out.raw

        def keyivgen(self, passwd, salt):
            saltlen = len(salt)
            passlen = len(passwd)
            iter = 0x3e8
            keylen = 80
            out = create_string_buffer(keylen)
            rv = PKCS5_PBKDF2_HMAC_SHA1(passwd, passlen, salt, saltlen, iter, keylen, out)
            return out.raw
    return LibCrypto

def _load_crypto():
    LibCrypto = None
    try:
        LibCrypto = _load_crypto_libcrypto()
    except (ImportError, DrmException):
        pass
    return LibCrypto

LibCrypto = _load_crypto()

#
# Utility Routines
#

# crypto digestroutines
import hashlib

def MD5(message):
    ctx = hashlib.md5()
    ctx.update(message)
    return ctx.digest()

def SHA1(message):
    ctx = hashlib.sha1()
    ctx.update(message)
    return ctx.digest()

def SHA256(message):
    ctx = hashlib.sha256()
    ctx.update(message)
    return ctx.digest()

# Various character maps used to decrypt books. Probably supposed to act as obfuscation
charMap1 = "n5Pr6St7Uv8Wx9YzAb0Cd1Ef2Gh3Jk4M"
charMap2 = "ZB0bYyc1xDdW2wEV3Ff7KkPpL8UuGA4gz-Tme9Nn_tHh5SvXCsIiR6rJjQaqlOoM" 

# For Future Reference from .kinf approach of K4PC
charMap5 = "AzB0bYyCeVvaZ3FfUuG4g-TtHh5SsIiR6rJjQq7KkPpL8lOoMm9Nn_c1XxDdW2wE"


def encode(data, map):
    result = ""
    for char in data:
        value = ord(char)
        Q = (value ^ 0x80) // len(map)
        R = value % len(map)
        result += map[Q]
        result += map[R]
    return result

# Hash the bytes in data and then encode the digest with the characters in map
def encodeHash(data,map):
    return encode(MD5(data),map)

# Decode the string in data with the characters in map. Returns the decoded bytes
def decode(data,map):
    result = ""
    for i in range (0,len(data)-1,2):
        high = map.find(data[i])
        low = map.find(data[i+1])
        if (high == -1) or (low == -1) :
            break
        value = (((high * len(map)) ^ 0x80) & 0xFF) + low
        result += pack("B",value)
    return result

# For Future Reference from .kinf approach of K4PC
# generate table of prime number less than or equal to int n
def primes(n):
    if n==2: return [2]
    elif n<2: return []
    s=range(3,n+1,2)
    mroot = n ** 0.5
    half=(n+1)/2-1
    i=0
    m=3
    while m <= mroot:
        if s[i]:
            j=(m*m-3)/2
            s[j]=0
            while j<half:
                s[j]=0
                j+=m
        i=i+1
        m=2*i+3
    return [2]+[x for x in s if x]



# uses a sub process to get the Hard Drive Serial Number using ioreg
# returns with the serial number of drive whose BSD Name is "disk0"
def GetVolumeSerialNumber():
    sernum = os.getenv('MYSERIALNUMBER')
    if sernum != None:
        return sernum
    cmdline = '/usr/sbin/ioreg -l -S -w 0 -r -c AppleAHCIDiskDriver'
    cmdline = cmdline.encode(sys.getfilesystemencoding())
    p = subprocess.Popen(cmdline, shell=True, stdin=None, stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=False)
    out1, out2 = p.communicate()
    reslst = out1.split('\n')
    cnt = len(reslst)
    bsdname = None
    sernum = None
    foundIt = False
    for j in xrange(cnt):
        resline = reslst[j]
        pp = resline.find('"Serial Number" = "')
        if pp >= 0:
            sernum = resline[pp+19:-1]
            sernum = sernum.strip()
        bb = resline.find('"BSD Name" = "')
        if bb >= 0:
            bsdname = resline[bb+14:-1]
            bsdname = bsdname.strip()
            if (bsdname == 'disk0') and (sernum != None):
                foundIt = True
                break
    if not foundIt:
        sernum = '9999999999'
    return sernum

# uses unix env to get username instead of using sysctlbyname 
def GetUserName():
    username = os.getenv('USER')
    return username

# implements an Pseudo Mac Version of Windows built-in Crypto routine
def CryptUnprotectData(encryptedData, salt):
    sp = GetVolumeSerialNumber() + '!@#' + GetUserName()
    passwdData = encode(SHA256(sp),charMap1)
    crp = LibCrypto()
    key_iv = crp.keyivgen(passwdData, salt)
    key = key_iv[0:32]
    iv = key_iv[32:48]
    crp.set_decrypt_key(key,iv)
    cleartext = crp.decrypt(encryptedData)
    return cleartext


# Locate the .kindle-info files
def getKindleInfoFiles(kInfoFiles):
    # first search for current .kindle-info files
    home = os.getenv('HOME')
    cmdline = 'find "' + home + '/Library/Application Support" -name ".kindle-info"'
    cmdline = cmdline.encode(sys.getfilesystemencoding())
    p1 = subprocess.Popen(cmdline, shell=True, stdin=None, stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=False)
    out1, out2 = p1.communicate()
    reslst = out1.split('\n')
    kinfopath = 'NONE'
    found = False
    for resline in reslst:
        if os.path.isfile(resline):
            kInfoFiles.append(resline)
            found = True
    # For Future Reference
    # 
    # # add any .kinf files 
    # cmdline = 'find "' + home + '/Library/Application Support" -name "rainier*.kinf"'
    # cmdline = cmdline.encode(sys.getfilesystemencoding())
    # p1 = subprocess.Popen(cmdline, shell=True, stdin=None, stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=False)
    # out1, out2 = p1.communicate()
    # reslst = out1.split('\n')
    # for resline in reslst:
    #     if os.path.isfile(resline):
    #         kInfoFiles.append(resline)
    #         found = True
    if not found:
        print('No kindle-info files have been found.')
    return kInfoFiles

# determine type of kindle info provided and return a 
# database of keynames and values
def getDBfromFile(kInfoFile):
    names = ["kindle.account.tokens","kindle.cookie.item","eulaVersionAccepted","login_date","kindle.token.item","login","kindle.key.item","kindle.name.info","kindle.device.info", "MazamaRandomNumber"]
    DB = {}
    cnt = 0
    infoReader = open(kInfoFile, 'r')
    hdr = infoReader.read(1)
    data = infoReader.read()

    if data.find('[') != -1 :

        # older style kindle-info file
        items = data.split('[')
        for item in items:
            if item != '':
                keyhash, rawdata = item.split(':')
                keyname = "unknown"
                for name in names:
                    if encodeHash(name,charMap2) == keyhash:
                        keyname = name
                        break
                if keyname == "unknown":
                    keyname = keyhash
                encryptedValue = decode(rawdata,charMap2)
                salt = '16743'
                cleartext = CryptUnprotectData(encryptedValue, salt)
                DB[keyname] = decode(cleartext,charMap1)
                cnt = cnt + 1
        if cnt == 0:
            DB = None
        return DB

    # For Future Reference taken from K4PC 1.5.0 .kinf
    # 
    # # else newer style .kinf file
    # # the .kinf file uses "/" to separate it into records
    # # so remove the trailing "/" to make it easy to use split
    # data = data[:-1]
    # items = data.split('/')
    # 
    # # loop through the item records until all are processed
    # while len(items) > 0:
    # 
    #     # get the first item record
    #     item = items.pop(0)
    # 
    #     # the first 32 chars of the first record of a group
    #     # is the MD5 hash of the key name encoded by charMap5
    #     keyhash = item[0:32]
    # 
    #     # the raw keyhash string is also used to create entropy for the actual
    #     # CryptProtectData Blob that represents that keys contents
    #     entropy = SHA1(keyhash)
    # 
    #     # the remainder of the first record when decoded with charMap5 
    #     # has the ':' split char followed by the string representation
    #     # of the number of records that follow
    #     # and make up the contents
    #     srcnt = decode(item[34:],charMap5)
    #     rcnt = int(srcnt)
    # 
    #     # read and store in rcnt records of data
    #     # that make up the contents value
    #     edlst = []
    #     for i in xrange(rcnt):
    #         item = items.pop(0)
    #         edlst.append(item)
    # 
    #     keyname = "unknown"
    #     for name in names:
    #         if encodeHash(name,charMap5) == keyhash:
    #             keyname = name
    #             break
    #     if keyname == "unknown":
    #         keyname = keyhash
    # 
    #     # the charMap5 encoded contents data has had a length 
    #     # of chars (always odd) cut off of the front and moved
    #     # to the end to prevent decoding using charMap5 from 
    #     # working properly, and thereby preventing the ensuing 
    #     # CryptUnprotectData call from succeeding.
    # 
    #     # The offset into the charMap5 encoded contents seems to be:
    #     # len(contents) - largest prime number less than or equal to int(len(content)/3)
    #     # (in other words split "about" 2/3rds of the way through)
    # 
    #     # move first offsets chars to end to align for decode by charMap5
    #     encdata = "".join(edlst)
    #     contlen = len(encdata)
    #     noffset = contlen - primes(int(contlen/3))[-1]
    # 
    #     # now properly split and recombine 
    #     # by moving noffset chars from the start of the 
    #     # string to the end of the string 
    #     pfx = encdata[0:noffset]
    #     encdata = encdata[noffset:]
    #     encdata = encdata + pfx
    # 
    #     # decode using Map5 to get the CryptProtect Data
    #     encryptedValue = decode(encdata,charMap5)
    #     DB[keyname] = CryptUnprotectData(encryptedValue, entropy, 1)
    #     cnt = cnt + 1

    if cnt == 0:
        DB = None
    return DB