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Support KFX VoucherEnvelope versions 2 and 3

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apprenticesakuya 2020-06-16 01:19:15 +00:00 committed by GitHub
parent 837562db66
commit 22d2b37e04
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1 changed files with 41 additions and 5 deletions
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46
DeDRM_plugin/ion.py
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@ -1,6 +1,6 @@
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Pascal implementation by lulzkabulz. Python translation by apprenticenaomi. DeDRM integration by anon.
# Pascal implementation by lulzkabulz. Python translation by apprenticenaomi. DeDRM integration by anon. VoucherEnvelope v2/v3 support by apprenticesakuya.
# BinaryIon.pas + DrmIon.pas + IonSymbols.pas
from __future__ import with_statement
@ -719,7 +719,8 @@ SYM_NAMES = [ 'com.amazon.drm.Envelope@1.0',
'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']
'com.amazon.drm.Compressed@1.0', 'page_index_table',
'com.amazon.drm.VoucherEnvelope@2.0', 'com.amazon.drm.VoucherEnvelope@3.0' ]
def addprottable(ion):
ion.addtocatalog("ProtectedData", 1, SYM_NAMES)
@ -741,8 +742,42 @@ def pkcs7unpad(msg, blocklen):
return msg[:-paddinglen]
# every VoucherEnvelope version has a corresponding "word" and magic number, used in obfuscating the shared secret
VOUCHER_VERSION_INFOS = {
2: [b'Antidisestablishmentarianism', 5],
3: [b'Floccinaucinihilipilification', 8]
}
# obfuscate shared secret according to the VoucherEnvelope version
def obfuscate(secret, version):
if version == 1: # v1 does not use obfuscation
return secret
params = VOUCHER_VERSION_INFOS[version]
word = params[0]
magic = params[1]
# extend secret so that its length is divisible by the magic number
if len(secret) % magic != 0:
secret = secret + b'\x00' * (magic - len(secret) % magic)
secret = bytearray(secret)
obfuscated = bytearray(len(secret))
wordhash = bytearray(hashlib.sha256(word).digest())
# shuffle secret and xor it with the first half of the word hash
for i in range(0, len(secret)):
index = i // (len(secret) // magic) + magic * (i % (len(secret) // magic))
obfuscated[index] = secret[i] ^ wordhash[index % 16]
return obfuscated
class DrmIonVoucher(object):
envelope = None
version = None
voucher = None
drmkey = None
license_type = "Unknown"
@ -777,9 +812,9 @@ class DrmIonVoucher(object):
else:
_assert(False, "Unknown lock parameter: %s" % param)
sharedsecret = shared.encode("UTF-8")
sharedsecret = obfuscate(shared.encode('ASCII'), self.version)
key = hmac.new(sharedsecret, sharedsecret[:5], digestmod=hashlib.sha256).digest()
key = hmac.new(sharedsecret, "PIDv3", digestmod=hashlib.sha256).digest()
aes = AES.new(key[:32], AES.MODE_CBC, self.cipheriv[:16])
b = aes.decrypt(self.ciphertext)
b = pkcs7unpad(b, 16)
@ -814,8 +849,9 @@ class DrmIonVoucher(object):
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",
_assert(self.envelope.next() == TID_STRUCT and str.startswith(self.envelope.gettypename(), "com.amazon.drm.VoucherEnvelope@"),
"Unknown type encountered in envelope, expected VoucherEnvelope")
self.version = int(self.envelope.gettypename().split('@')[1][:-2])
self.envelope.stepin()
while self.envelope.hasnext():