DeDRM_tools/dedrm_src/ion.py

986 lines
30 KiB
Python

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Pascal implementation by lulzkabulz. Python translation by apprenticenaomi. DeDRM integration by anon.
# BinaryIon.pas + DrmIon.pas + IonSymbols.pas
from __future__ import with_statement
import collections
import hashlib
import hmac
import os
import os.path
import struct
try:
from cStringIO import StringIO
except ImportError:
from StringIO import StringIO
from Crypto.Cipher import AES
from Crypto.Util.py3compat import bchr, bord
try:
# lzma library from calibre 2.35.0 or later
import lzma.lzma1 as calibre_lzma
except ImportError:
calibre_lzma = None
try:
import lzma
except ImportError:
# Need pip backports.lzma on Python <3.3
try:
from backports import lzma
except ImportError:
# Windows-friendly choice: pylzma wheels
import pylzma as lzma
TID_NULL = 0
TID_BOOLEAN = 1
TID_POSINT = 2
TID_NEGINT = 3
TID_FLOAT = 4
TID_DECIMAL = 5
TID_TIMESTAMP = 6
TID_SYMBOL = 7
TID_STRING = 8
TID_CLOB = 9
TID_BLOB = 0xA
TID_LIST = 0xB
TID_SEXP = 0xC
TID_STRUCT = 0xD
TID_TYPEDECL = 0xE
TID_UNUSED = 0xF
SID_UNKNOWN = -1
SID_ION = 1
SID_ION_1_0 = 2
SID_ION_SYMBOL_TABLE = 3
SID_NAME = 4
SID_VERSION = 5
SID_IMPORTS = 6
SID_SYMBOLS = 7
SID_MAX_ID = 8
SID_ION_SHARED_SYMBOL_TABLE = 9
SID_ION_1_0_MAX = 10
LEN_IS_VAR_LEN = 0xE
LEN_IS_NULL = 0xF
VERSION_MARKER = b"\x01\x00\xEA"
# asserts must always raise exceptions for proper functioning
def _assert(test, msg="Exception"):
if not test:
raise Exception(msg)
class SystemSymbols(object):
ION = '$ion'
ION_1_0 = '$ion_1_0'
ION_SYMBOL_TABLE = '$ion_symbol_table'
NAME = 'name'
VERSION = 'version'
IMPORTS = 'imports'
SYMBOLS = 'symbols'
MAX_ID = 'max_id'
ION_SHARED_SYMBOL_TABLE = '$ion_shared_symbol_table'
class IonCatalogItem(object):
name = ""
version = 0
symnames = []
def __init__(self, name, version, symnames):
self.name = name
self.version = version
self.symnames = symnames
class SymbolToken(object):
text = ""
sid = 0
def __init__(self, text, sid):
if text == "" and sid == 0:
raise ValueError("Symbol token must have Text or SID")
self.text = text
self.sid = sid
class SymbolTable(object):
table = None
def __init__(self):
self.table = [None] * SID_ION_1_0_MAX
self.table[SID_ION] = SystemSymbols.ION
self.table[SID_ION_1_0] = SystemSymbols.ION_1_0
self.table[SID_ION_SYMBOL_TABLE] = SystemSymbols.ION_SYMBOL_TABLE
self.table[SID_NAME] = SystemSymbols.NAME
self.table[SID_VERSION] = SystemSymbols.VERSION
self.table[SID_IMPORTS] = SystemSymbols.IMPORTS
self.table[SID_SYMBOLS] = SystemSymbols.SYMBOLS
self.table[SID_MAX_ID] = SystemSymbols.MAX_ID
self.table[SID_ION_SHARED_SYMBOL_TABLE] = SystemSymbols.ION_SHARED_SYMBOL_TABLE
def findbyid(self, sid):
if sid < 1:
raise ValueError("Invalid symbol id")
if sid < len(self.table):
return self.table[sid]
else:
return ""
def import_(self, table, maxid):
for i in range(maxid):
self.table.append(table.symnames[i])
def importunknown(self, name, maxid):
for i in range(maxid):
self.table.append("%s#%d" % (name, i + 1))
class ParserState:
Invalid,BeforeField,BeforeTID,BeforeValue,AfterValue,EOF = 1,2,3,4,5,6
ContainerRec = collections.namedtuple("ContainerRec", "nextpos, tid, remaining")
class BinaryIonParser(object):
eof = False
state = None
localremaining = 0
needhasnext = False
isinstruct = False
valuetid = 0
valuefieldid = 0
parenttid = 0
valuelen = 0
valueisnull = False
valueistrue = False
value = None
didimports = False
def __init__(self, stream):
self.annotations = []
self.catalog = []
self.stream = stream
self.initpos = stream.tell()
self.reset()
self.symbols = SymbolTable()
def reset(self):
self.state = ParserState.BeforeTID
self.needhasnext = True
self.localremaining = -1
self.eof = False
self.isinstruct = False
self.containerstack = []
self.stream.seek(self.initpos)
def addtocatalog(self, name, version, symbols):
self.catalog.append(IonCatalogItem(name, version, symbols))
def hasnext(self):
while self.needhasnext and not self.eof:
self.hasnextraw()
if len(self.containerstack) == 0 and not self.valueisnull:
if self.valuetid == TID_SYMBOL:
if self.value == SID_ION_1_0:
self.needhasnext = True
elif self.valuetid == TID_STRUCT:
for a in self.annotations:
if a == SID_ION_SYMBOL_TABLE:
self.parsesymboltable()
self.needhasnext = True
break
return not self.eof
def hasnextraw(self):
self.clearvalue()
while self.valuetid == -1 and not self.eof:
self.needhasnext = False
if self.state == ParserState.BeforeField:
_assert(self.valuefieldid == SID_UNKNOWN)
self.valuefieldid = self.readfieldid()
if self.valuefieldid != SID_UNKNOWN:
self.state = ParserState.BeforeTID
else:
self.eof = True
elif self.state == ParserState.BeforeTID:
self.state = ParserState.BeforeValue
self.valuetid = self.readtypeid()
if self.valuetid == -1:
self.state = ParserState.EOF
self.eof = True
break
if self.valuetid == TID_TYPEDECL:
if self.valuelen == 0:
self.checkversionmarker()
else:
self.loadannotations()
elif self.state == ParserState.BeforeValue:
self.skip(self.valuelen)
self.state = ParserState.AfterValue
elif self.state == ParserState.AfterValue:
if self.isinstruct:
self.state = ParserState.BeforeField
else:
self.state = ParserState.BeforeTID
else:
_assert(self.state == ParserState.EOF)
def next(self):
if self.hasnext():
self.needhasnext = True
return self.valuetid
else:
return -1
def push(self, typeid, nextposition, nextremaining):
self.containerstack.append(ContainerRec(nextpos=nextposition, tid=typeid, remaining=nextremaining))
def stepin(self):
_assert(self.valuetid in [TID_STRUCT, TID_LIST, TID_SEXP] and not self.eof,
"valuetid=%s eof=%s" % (self.valuetid, self.eof))
_assert((not self.valueisnull or self.state == ParserState.AfterValue) and
(self.valueisnull or self.state == ParserState.BeforeValue))
nextrem = self.localremaining
if nextrem != -1:
nextrem -= self.valuelen
if nextrem < 0:
nextrem = 0
self.push(self.parenttid, self.stream.tell() + self.valuelen, nextrem)
self.isinstruct = (self.valuetid == TID_STRUCT)
if self.isinstruct:
self.state = ParserState.BeforeField
else:
self.state = ParserState.BeforeTID
self.localremaining = self.valuelen
self.parenttid = self.valuetid
self.clearvalue()
self.needhasnext = True
def stepout(self):
rec = self.containerstack.pop()
self.eof = False
self.parenttid = rec.tid
if self.parenttid == TID_STRUCT:
self.isinstruct = True
self.state = ParserState.BeforeField
else:
self.isinstruct = False
self.state = ParserState.BeforeTID
self.needhasnext = True
self.clearvalue()
curpos = self.stream.tell()
if rec.nextpos > curpos:
self.skip(rec.nextpos - curpos)
else:
_assert(rec.nextpos == curpos)
self.localremaining = rec.remaining
def read(self, count=1):
if self.localremaining != -1:
self.localremaining -= count
_assert(self.localremaining >= 0)
result = self.stream.read(count)
if len(result) == 0:
raise EOFError()
return result
def readfieldid(self):
if self.localremaining != -1 and self.localremaining < 1:
return -1
try:
return self.readvaruint()
except EOFError:
return -1
def readtypeid(self):
if self.localremaining != -1:
if self.localremaining < 1:
return -1
self.localremaining -= 1
b = self.stream.read(1)
if len(b) < 1:
return -1
b = bord(b)
result = b >> 4
ln = b & 0xF
if ln == LEN_IS_VAR_LEN:
ln = self.readvaruint()
elif ln == LEN_IS_NULL:
ln = 0
self.state = ParserState.AfterValue
elif result == TID_NULL:
# Must have LEN_IS_NULL
_assert(False)
elif result == TID_BOOLEAN:
_assert(ln <= 1)
self.valueistrue = (ln == 1)
ln = 0
self.state = ParserState.AfterValue
elif result == TID_STRUCT:
if ln == 1:
ln = self.readvaruint()
self.valuelen = ln
return result
def readvarint(self):
b = bord(self.read())
negative = ((b & 0x40) != 0)
result = (b & 0x3F)
i = 0
while (b & 0x80) == 0 and i < 4:
b = bord(self.read())
result = (result << 7) | (b & 0x7F)
i += 1
_assert(i < 4 or (b & 0x80) != 0, "int overflow")
if negative:
return -result
return result
def readvaruint(self):
b = bord(self.read())
result = (b & 0x7F)
i = 0
while (b & 0x80) == 0 and i < 4:
b = bord(self.read())
result = (result << 7) | (b & 0x7F)
i += 1
_assert(i < 4 or (b & 0x80) != 0, "int overflow")
return result
def readdecimal(self):
if self.valuelen == 0:
return 0.
rem = self.localremaining - self.valuelen
self.localremaining = self.valuelen
exponent = self.readvarint()
_assert(self.localremaining > 0, "Only exponent in ReadDecimal")
_assert(self.localremaining <= 8, "Decimal overflow")
signed = False
b = [bord(x) for x in self.read(self.localremaining)]
if (b[0] & 0x80) != 0:
b[0] = b[0] & 0x7F
signed = True
# Convert variably sized network order integer into 64-bit little endian
j = 0
vb = [0] * 8
for i in range(len(b), -1, -1):
vb[i] = b[j]
j += 1
v = struct.unpack("<Q", b"".join(bchr(x) for x in vb))[0]
result = v * (10 ** exponent)
if signed:
result = -result
self.localremaining = rem
return result
def skip(self, count):
if self.localremaining != -1:
self.localremaining -= count
if self.localremaining < 0:
raise EOFError()
self.stream.seek(count, os.SEEK_CUR)
def parsesymboltable(self):
self.next() # shouldn't do anything?
_assert(self.valuetid == TID_STRUCT)
if self.didimports:
return
self.stepin()
fieldtype = self.next()
while fieldtype != -1:
if not self.valueisnull:
_assert(self.valuefieldid == SID_IMPORTS, "Unsupported symbol table field id")
if fieldtype == TID_LIST:
self.gatherimports()
fieldtype = self.next()
self.stepout()
self.didimports = True
def gatherimports(self):
self.stepin()
t = self.next()
while t != -1:
if not self.valueisnull and t == TID_STRUCT:
self.readimport()
t = self.next()
self.stepout()
def readimport(self):
version = -1
maxid = -1
name = ""
self.stepin()
t = self.next()
while t != -1:
if not self.valueisnull and self.valuefieldid != SID_UNKNOWN:
if self.valuefieldid == SID_NAME:
name = self.stringvalue()
elif self.valuefieldid == SID_VERSION:
version = self.intvalue()
elif self.valuefieldid == SID_MAX_ID:
maxid = self.intvalue()
t = self.next()
self.stepout()
if name == "" or name == SystemSymbols.ION:
return
if version < 1:
version = 1
table = self.findcatalogitem(name)
if maxid < 0:
_assert(table is not None and version == table.version, "Import %s lacks maxid" % name)
maxid = len(table.symnames)
if table is not None:
self.symbols.import_(table, min(maxid, len(table.symnames)))
else:
self.symbols.importunknown(name, maxid)
def intvalue(self):
_assert(self.valuetid in [TID_POSINT, TID_NEGINT], "Not an int")
self.preparevalue()
return self.value
def stringvalue(self):
_assert(self.valuetid == TID_STRING, "Not a string")
if self.valueisnull:
return ""
self.preparevalue()
return self.value
def symbolvalue(self):
_assert(self.valuetid == TID_SYMBOL, "Not a symbol")
self.preparevalue()
result = self.symbols.findbyid(self.value)
if result == "":
result = "SYMBOL#%d" % self.value
return result
def lobvalue(self):
_assert(self.valuetid in [TID_CLOB, TID_BLOB], "Not a LOB type: %s" % self.getfieldname())
if self.valueisnull:
return None
result = self.read(self.valuelen)
self.state = ParserState.AfterValue
return result
def decimalvalue(self):
_assert(self.valuetid == TID_DECIMAL, "Not a decimal")
self.preparevalue()
return self.value
def preparevalue(self):
if self.value is None:
self.loadscalarvalue()
def loadscalarvalue(self):
if self.valuetid not in [TID_NULL, TID_BOOLEAN, TID_POSINT, TID_NEGINT,
TID_FLOAT, TID_DECIMAL, TID_TIMESTAMP,
TID_SYMBOL, TID_STRING]:
return
if self.valueisnull:
self.value = None
return
if self.valuetid == TID_STRING:
self.value = self.read(self.valuelen).decode("UTF-8")
elif self.valuetid in (TID_POSINT, TID_NEGINT, TID_SYMBOL):
if self.valuelen == 0:
self.value = 0
else:
_assert(self.valuelen <= 4, "int too long: %d" % self.valuelen)
v = 0
for i in range(self.valuelen - 1, -1, -1):
v = (v | (bord(self.read()) << (i * 8)))
if self.valuetid == TID_NEGINT:
self.value = -v
else:
self.value = v
elif self.valuetid == TID_DECIMAL:
self.value = self.readdecimal()
#else:
# _assert(False, "Unhandled scalar type %d" % self.valuetid)
self.state = ParserState.AfterValue
def clearvalue(self):
self.valuetid = -1
self.value = None
self.valueisnull = False
self.valuefieldid = SID_UNKNOWN
self.annotations = []
def loadannotations(self):
ln = self.readvaruint()
maxpos = self.stream.tell() + ln
while self.stream.tell() < maxpos:
self.annotations.append(self.readvaruint())
self.valuetid = self.readtypeid()
def checkversionmarker(self):
for i in VERSION_MARKER:
_assert(self.read() == i, "Unknown version marker")
self.valuelen = 0
self.valuetid = TID_SYMBOL
self.value = SID_ION_1_0
self.valueisnull = False
self.valuefieldid = SID_UNKNOWN
self.state = ParserState.AfterValue
def findcatalogitem(self, name):
for result in self.catalog:
if result.name == name:
return result
def forceimport(self, symbols):
item = IonCatalogItem("Forced", 1, symbols)
self.symbols.import_(item, len(symbols))
def getfieldname(self):
if self.valuefieldid == SID_UNKNOWN:
return ""
return self.symbols.findbyid(self.valuefieldid)
def getfieldnamesymbol(self):
return SymbolToken(self.getfieldname(), self.valuefieldid)
def gettypename(self):
if len(self.annotations) == 0:
return ""
return self.symbols.findbyid(self.annotations[0])
@staticmethod
def printlob(b):
if b is None:
return "null"
result = ""
for i in b:
result += ("%02x " % bord(i))
if len(result) > 0:
result = result[:-1]
return result
def ionwalk(self, supert, indent, lst):
while self.hasnext():
if supert == TID_STRUCT:
L = self.getfieldname() + ":"
else:
L = ""
t = self.next()
if t in [TID_STRUCT, TID_LIST]:
if L != "":
lst.append(indent + L)
L = self.gettypename()
if L != "":
lst.append(indent + L + "::")
if t == TID_STRUCT:
lst.append(indent + "{")
else:
lst.append(indent + "[")
self.stepin()
self.ionwalk(t, indent + " ", lst)
self.stepout()
if t == TID_STRUCT:
lst.append(indent + "}")
else:
lst.append(indent + "]")
else:
if t == TID_STRING:
L += ('"%s"' % self.stringvalue())
elif t in [TID_CLOB, TID_BLOB]:
L += ("{%s}" % self.printlob(self.lobvalue()))
elif t == TID_POSINT:
L += str(self.intvalue())
elif t == TID_SYMBOL:
tn = self.gettypename()
if tn != "":
tn += "::"
L += tn + self.symbolvalue()
elif t == TID_DECIMAL:
L += str(self.decimalvalue())
else:
L += ("TID %d" % t)
lst.append(indent + L)
def print_(self, lst):
self.reset()
self.ionwalk(-1, "", lst)
SYM_NAMES = [ 'com.amazon.drm.Envelope@1.0',
'com.amazon.drm.EnvelopeMetadata@1.0', 'size', 'page_size',
'encryption_key', 'encryption_transformation',
'encryption_voucher', 'signing_key', 'signing_algorithm',
'signing_voucher', 'com.amazon.drm.EncryptedPage@1.0',
'cipher_text', 'cipher_iv', 'com.amazon.drm.Signature@1.0',
'data', 'com.amazon.drm.EnvelopeIndexTable@1.0', 'length',
'offset', 'algorithm', 'encoded', 'encryption_algorithm',
'hashing_algorithm', 'expires', 'format', 'id',
'lock_parameters', 'strategy', 'com.amazon.drm.Key@1.0',
'com.amazon.drm.KeySet@1.0', 'com.amazon.drm.PIDv3@1.0',
'com.amazon.drm.PlainTextPage@1.0',
'com.amazon.drm.PlainText@1.0', 'com.amazon.drm.PrivateKey@1.0',
'com.amazon.drm.PublicKey@1.0', 'com.amazon.drm.SecretKey@1.0',
'com.amazon.drm.Voucher@1.0', 'public_key', 'private_key',
'com.amazon.drm.KeyPair@1.0', 'com.amazon.drm.ProtectedData@1.0',
'doctype', 'com.amazon.drm.EnvelopeIndexTableOffset@1.0',
'enddoc', 'license_type', 'license', 'watermark', 'key', 'value',
'com.amazon.drm.License@1.0', 'category', 'metadata',
'categorized_metadata', 'com.amazon.drm.CategorizedMetadata@1.0',
'com.amazon.drm.VoucherEnvelope@1.0', 'mac', 'voucher',
'com.amazon.drm.ProtectedData@2.0',
'com.amazon.drm.Envelope@2.0',
'com.amazon.drm.EnvelopeMetadata@2.0',
'com.amazon.drm.EncryptedPage@2.0',
'com.amazon.drm.PlainText@2.0', 'compression_algorithm',
'com.amazon.drm.Compressed@1.0', 'priority', 'refines']
def addprottable(ion):
ion.addtocatalog("ProtectedData", 1, SYM_NAMES)
def pkcs7pad(msg, blocklen):
paddinglen = blocklen - len(msg) % blocklen
padding = bchr(paddinglen) * paddinglen
return msg + padding
def pkcs7unpad(msg, blocklen):
_assert(len(msg) % blocklen == 0)
paddinglen = bord(msg[-1])
_assert(paddinglen > 0 and paddinglen <= blocklen, "Incorrect padding - Wrong key")
_assert(msg[-paddinglen:] == bchr(paddinglen) * paddinglen, "Incorrect padding - Wrong key")
return msg[:-paddinglen]
class DrmIonVoucher(object):
envelope = None
voucher = None
drmkey = None
license_type = "Unknown"
encalgorithm = ""
enctransformation = ""
hashalgorithm = ""
lockparams = None
ciphertext = b""
cipheriv = b""
secretkey = b""
def __init__(self, voucherenv, dsn, secret):
self.dsn,self.secret = dsn,secret
self.lockparams = []
self.envelope = BinaryIonParser(voucherenv)
addprottable(self.envelope)
def decryptvoucher(self):
shared = "PIDv3" + self.encalgorithm + self.enctransformation + self.hashalgorithm
self.lockparams.sort()
for param in self.lockparams:
if param == "ACCOUNT_SECRET":
shared += param + self.secret
elif param == "CLIENT_ID":
shared += param + self.dsn
else:
_assert(False, "Unknown lock parameter: %s" % param)
sharedsecret = shared.encode("UTF-8")
key = hmac.new(sharedsecret, sharedsecret[:5], digestmod=hashlib.sha256).digest()
aes = AES.new(key[:32], AES.MODE_CBC, self.cipheriv[:16])
b = aes.decrypt(self.ciphertext)
b = pkcs7unpad(b, 16)
self.drmkey = BinaryIonParser(StringIO(b))
addprottable(self.drmkey)
_assert(self.drmkey.hasnext() and self.drmkey.next() == TID_LIST and self.drmkey.gettypename() == "com.amazon.drm.KeySet@1.0",
"Expected KeySet, got %s" % self.drmkey.gettypename())
self.drmkey.stepin()
while self.drmkey.hasnext():
self.drmkey.next()
if self.drmkey.gettypename() != "com.amazon.drm.SecretKey@1.0":
continue
self.drmkey.stepin()
while self.drmkey.hasnext():
self.drmkey.next()
if self.drmkey.getfieldname() == "algorithm":
_assert(self.drmkey.stringvalue() == "AES", "Unknown cipher algorithm: %s" % self.drmkey.stringvalue())
elif self.drmkey.getfieldname() == "format":
_assert(self.drmkey.stringvalue() == "RAW", "Unknown key format: %s" % self.drmkey.stringvalue())
elif self.drmkey.getfieldname() == "encoded":
self.secretkey = self.drmkey.lobvalue()
self.drmkey.stepout()
break
self.drmkey.stepout()
def parse(self):
self.envelope.reset()
_assert(self.envelope.hasnext(), "Envelope is empty")
_assert(self.envelope.next() == TID_STRUCT and self.envelope.gettypename() == "com.amazon.drm.VoucherEnvelope@1.0",
"Unknown type encountered in envelope, expected VoucherEnvelope")
self.envelope.stepin()
while self.envelope.hasnext():
self.envelope.next()
field = self.envelope.getfieldname()
if field == "voucher":
self.voucher = BinaryIonParser(StringIO(self.envelope.lobvalue()))
addprottable(self.voucher)
continue
elif field != "strategy":
continue
_assert(self.envelope.gettypename() == "com.amazon.drm.PIDv3@1.0", "Unknown strategy: %s" % self.envelope.gettypename())
self.envelope.stepin()
while self.envelope.hasnext():
self.envelope.next()
field = self.envelope.getfieldname()
if field == "encryption_algorithm":
self.encalgorithm = self.envelope.stringvalue()
elif field == "encryption_transformation":
self.enctransformation = self.envelope.stringvalue()
elif field == "hashing_algorithm":
self.hashalgorithm = self.envelope.stringvalue()
elif field == "lock_parameters":
self.envelope.stepin()
while self.envelope.hasnext():
_assert(self.envelope.next() == TID_STRING, "Expected string list for lock_parameters")
self.lockparams.append(self.envelope.stringvalue())
self.envelope.stepout()
self.envelope.stepout()
self.parsevoucher()
def parsevoucher(self):
_assert(self.voucher.hasnext(), "Voucher is empty")
_assert(self.voucher.next() == TID_STRUCT and self.voucher.gettypename() == "com.amazon.drm.Voucher@1.0",
"Unknown type, expected Voucher")
self.voucher.stepin()
while self.voucher.hasnext():
self.voucher.next()
if self.voucher.getfieldname() == "cipher_iv":
self.cipheriv = self.voucher.lobvalue()
elif self.voucher.getfieldname() == "cipher_text":
self.ciphertext = self.voucher.lobvalue()
elif self.voucher.getfieldname() == "license":
_assert(self.voucher.gettypename() == "com.amazon.drm.License@1.0",
"Unknown license: %s" % self.voucher.gettypename())
self.voucher.stepin()
while self.voucher.hasnext():
self.voucher.next()
if self.voucher.getfieldname() == "license_type":
self.license_type = self.voucher.stringvalue()
self.voucher.stepout()
def printenvelope(self, lst):
self.envelope.print_(lst)
def printkey(self, lst):
if self.voucher is None:
self.parse()
if self.drmkey is None:
self.decryptvoucher()
self.drmkey.print_(lst)
def printvoucher(self, lst):
if self.voucher is None:
self.parse()
self.voucher.print_(lst)
def getlicensetype(self):
return self.license_type
class DrmIon(object):
ion = None
voucher = None
vouchername = ""
key = b""
onvoucherrequired = None
def __init__(self, ionstream, onvoucherrequired):
self.ion = BinaryIonParser(ionstream)
addprottable(self.ion)
self.onvoucherrequired = onvoucherrequired
def parse(self, outpages):
self.ion.reset()
_assert(self.ion.hasnext(), "DRMION envelope is empty")
_assert(self.ion.next() == TID_SYMBOL and self.ion.gettypename() == "doctype", "Expected doctype symbol")
_assert(self.ion.next() == TID_LIST and self.ion.gettypename() in ["com.amazon.drm.Envelope@1.0", "com.amazon.drm.Envelope@2.0"],
"Unknown type encountered in DRMION envelope, expected Envelope, got %s" % self.ion.gettypename())
while True:
if self.ion.gettypename() == "enddoc":
break
self.ion.stepin()
while self.ion.hasnext():
self.ion.next()
if self.ion.gettypename() in ["com.amazon.drm.EnvelopeMetadata@1.0", "com.amazon.drm.EnvelopeMetadata@2.0"]:
self.ion.stepin()
while self.ion.hasnext():
self.ion.next()
if self.ion.getfieldname() != "encryption_voucher":
continue
if self.vouchername == "":
self.vouchername = self.ion.stringvalue()
self.voucher = self.onvoucherrequired(self.vouchername)
self.key = self.voucher.secretkey
_assert(self.key is not None, "Unable to obtain secret key from voucher")
else:
_assert(self.vouchername == self.ion.stringvalue(),
"Unexpected: Different vouchers required for same file?")
self.ion.stepout()
elif self.ion.gettypename() in ["com.amazon.drm.EncryptedPage@1.0", "com.amazon.drm.EncryptedPage@2.0"]:
decompress = False
ct = None
civ = None
self.ion.stepin()
while self.ion.hasnext():
self.ion.next()
if self.ion.gettypename() == "com.amazon.drm.Compressed@1.0":
decompress = True
if self.ion.getfieldname() == "cipher_text":
ct = self.ion.lobvalue()
elif self.ion.getfieldname() == "cipher_iv":
civ = self.ion.lobvalue()
if ct is not None and civ is not None:
self.processpage(ct, civ, outpages, decompress)
self.ion.stepout()
self.ion.stepout()
if not self.ion.hasnext():
break
self.ion.next()
def print_(self, lst):
self.ion.print_(lst)
def processpage(self, ct, civ, outpages, decompress):
aes = AES.new(self.key[:16], AES.MODE_CBC, civ[:16])
msg = pkcs7unpad(aes.decrypt(ct), 16)
if not decompress:
outpages.write(msg)
return
_assert(msg[0] == b"\x00", "LZMA UseFilter not supported")
if calibre_lzma is not None:
with calibre_lzma.decompress(msg[1:], bufsize=0x1000000) as f:
f.seek(0)
outpages.write(f.read())
return
decomp = lzma.LZMADecompressor(format=lzma.FORMAT_ALONE)
while not decomp.eof:
segment = decomp.decompress(msg[1:])
msg = b"" # Contents were internally buffered after the first call
outpages.write(segment)