Try to add support for new K4PC

Co-authored-by: Andrew Innes <andrew.c12@gmail.com>
Co-authored-by: Satsuoni <satsuoni@hotmail.com>
This commit is contained in:
NoDRM 2023-06-23 19:30:06 +02:00
parent fb8b003444
commit 740b46546f
2 changed files with 120 additions and 5 deletions

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@ -89,3 +89,4 @@ List of changes since the fork of Apprentice Harper's repository:
- PDF: Ignore invalid PDF objids unless the script is running in strict mode. Fixes some PDFs, apparently. Fixes #233. - PDF: Ignore invalid PDF objids unless the script is running in strict mode. Fixes some PDFs, apparently. Fixes #233.
- Bugfix: EPUBs with remaining content in the encryption.xml after decryption weren't written correctly. - Bugfix: EPUBs with remaining content in the encryption.xml after decryption weren't written correctly.
- Support for Adobe's 'aes128-cbc-uncompressed' encryption method (fixes #242). - Support for Adobe's 'aes128-cbc-uncompressed' encryption method (fixes #242).
- Two bugfixes for Amazon DeDRM from Satuoni ( https://github.com/noDRM/DeDRM_tools/issues/315#issuecomment-1508305428 ) and andrewc12 ( https://github.com/andrewc12/DeDRM_tools/commit/d9233d61f00d4484235863969919059f4d0b2057 ) that might make the plugin work with newer versions.

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@ -835,6 +835,107 @@ def obfuscate(secret, version):
return obfuscated return obfuscated
# scramble() and obfuscate2() from https://github.com/andrewc12/DeDRM_tools/commit/d9233d61f00d4484235863969919059f4d0b2057
def scramble(st,magic):
ret=bytearray(len(st))
padlen=len(st)
for counter in range(len(st)):
ivar2=(padlen//2)-2*(counter%magic)+magic+counter-1
ret[ivar2%padlen]=st[counter]
return ret
def obfuscate2(secret, version):
if version == 1: # v1 does not use obfuscation
return secret
magic, word = OBFUSCATION_TABLE["V%d" % version]
# 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)
obfuscated = bytearray(len(secret))
wordhash = bytearray(hashlib.sha256(word).digest()[16:])
#print(wordhash.hex())
shuffled = bytearray(scramble(secret,magic))
for i in range(0, len(secret)):
obfuscated[i] = shuffled[i] ^ wordhash[i % 16]
return obfuscated
# scramble3() and obfuscate3() from https://github.com/Satsuoni/DeDRM_tools/commit/da6b6a0c911b6d45fe1b13042b690daebc1cc22f
def scramble3(st,magic):
ret=bytearray(len(st))
padlen=len(st)
divs = padlen // magic
cntr = 0
iVar6 = 0
offset = 0
if (0 < ((magic - 1) + divs)):
while True:
if (offset & 1) == 0 :
uVar4 = divs - 1
if offset < divs:
iVar3 = 0
uVar4 = offset
else:
iVar3 = (offset - divs) + 1
if uVar4>=0:
iVar5 = uVar4 * magic
index = ((padlen - 1) - cntr)
while True:
if (magic <= iVar3): break
ret[index] = st[iVar3 + iVar5]
iVar3 = iVar3 + 1
cntr = cntr + 1
uVar4 = uVar4 - 1
iVar5 = iVar5 - magic
index -= 1
if uVar4<=-1: break
else:
if (offset < magic):
iVar3 = 0
else :
iVar3 = (offset - magic) + 1
if (iVar3 < divs):
uVar4 = offset
if (magic <= offset):
uVar4 = magic - 1
index = ((padlen - 1) - cntr)
iVar5 = iVar3 * magic
while True:
if (uVar4 < 0) : break
iVar3 += 1
ret[index] = st[uVar4 + iVar5]
uVar4 -= 1
index=index-1
iVar5 = iVar5 + magic;
cntr += 1;
if iVar3>=divs: break
offset = offset + 1
if offset >= ((magic - 1) + divs) :break
return ret
#not sure if the third variant is used anywhere, but it is in Kindle, so I tried to add it
def obfuscate3(secret, version):
if version == 1: # v1 does not use obfuscation
return secret
magic, word = OBFUSCATION_TABLE["V%d" % version]
# 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())
#print(wordhash.hex())
shuffled=bytearray(scramble3(secret,magic))
#print(shuffled)
# shuffle secret and xor it with the first half of the word hash
for i in range(0, len(secret)):
obfuscated[i] = shuffled[i] ^ wordhash[i % 16]
return obfuscated
class DrmIonVoucher(object): class DrmIonVoucher(object):
envelope = None envelope = None
version = None version = None
@ -878,12 +979,25 @@ class DrmIonVoucher(object):
else: else:
_assert(False, "Unknown lock parameter: %s" % param) _assert(False, "Unknown lock parameter: %s" % param)
sharedsecret = obfuscate(shared, self.version)
key = hmac.new(sharedsecret, b"PIDv3", digestmod=hashlib.sha256).digest() sharedsecrets = [obfuscate(shared, self.version),obfuscate2(shared, self.version),obfuscate3(shared, self.version)]
aes = AES.new(key[:32], AES.MODE_CBC, self.cipheriv[:16]) decrypted=False
b = aes.decrypt(self.ciphertext) ex=None
b = pkcs7unpad(b, 16) for sharedsecret in sharedsecrets:
key = hmac.new(sharedsecret, b"PIDv3", digestmod=hashlib.sha256).digest()
aes = AES.new(key[:32], AES.MODE_CBC, self.cipheriv[:16])
try:
b = aes.decrypt(self.ciphertext)
b = pkcs7unpad(b, 16)
decrypted=True
print("Decryption succeeded")
break
except Exception as ex:
print("Decryption failed, trying next fallback ")
if not decrypted:
raise ex
sharedsecret = obfuscate(shared, self.version)
self.drmkey = BinaryIonParser(BytesIO(b)) self.drmkey = BinaryIonParser(BytesIO(b))
addprottable(self.drmkey) addprottable(self.drmkey)