365 lines
15 KiB
Python
365 lines
15 KiB
Python
|
import base64
|
||
|
|
|
||
|
|
import os
|
||
|
|
import time
|
||
|
|
import binascii
|
||
|
|
|
||
|
|
from google.protobuf.message import DecodeError
|
||
|
|
from google.protobuf import text_format
|
||
|
|
|
||
|
|
from pywidevine.cdm.formats import wv_proto2_pb2 as wv_proto2
|
||
|
|
from pywidevine.cdm.session import Session
|
||
|
|
from pywidevine.cdm.key import Key
|
||
|
|
from Cryptodome.Random import get_random_bytes
|
||
|
|
from Cryptodome.Random import random
|
||
|
|
from Cryptodome.Cipher import PKCS1_OAEP, AES
|
||
|
|
from Cryptodome.Hash import CMAC, SHA256, HMAC, SHA1
|
||
|
|
from Cryptodome.PublicKey import RSA
|
||
|
|
from Cryptodome.Signature import pss
|
||
|
|
from Cryptodome.Util import Padding
|
||
|
|
import logging
|
||
|
|
|
||
|
|
class Cdm:
|
||
|
|
def __init__(self):
|
||
|
|
self.logger = logging.getLogger(__name__)
|
||
|
|
self.sessions = {}
|
||
|
|
|
||
|
|
def open_session(self, init_data_b64, device, raw_init_data = None, offline=False):
|
||
|
|
self.logger.debug("open_session(init_data_b64={}, device={}".format(init_data_b64, device))
|
||
|
|
self.logger.info("opening new cdm session")
|
||
|
|
if device.session_id_type == 'android':
|
||
|
|
# format: 16 random hexdigits, 2 digit counter, 14 0s
|
||
|
|
rand_ascii = ''.join(random.choice('ABCDEF0123456789') for _ in range(16))
|
||
|
|
counter = '01' # this resets regularly so its fine to use 01
|
||
|
|
rest = '00000000000000'
|
||
|
|
session_id = rand_ascii + counter + rest
|
||
|
|
session_id = session_id.encode('ascii')
|
||
|
|
elif device.session_id_type == 'chrome':
|
||
|
|
rand_bytes = get_random_bytes(16)
|
||
|
|
session_id = rand_bytes
|
||
|
|
else:
|
||
|
|
# other formats NYI
|
||
|
|
self.logger.error("device type is unusable")
|
||
|
|
return 1
|
||
|
|
if raw_init_data and isinstance(raw_init_data, (bytes, bytearray)):
|
||
|
|
# used for NF key exchange, where they don't provide a valid PSSH
|
||
|
|
init_data = raw_init_data
|
||
|
|
self.raw_pssh = True
|
||
|
|
else:
|
||
|
|
init_data = self._parse_init_data(init_data_b64)
|
||
|
|
self.raw_pssh = False
|
||
|
|
|
||
|
|
if init_data:
|
||
|
|
new_session = Session(session_id, init_data, device, offline)
|
||
|
|
else:
|
||
|
|
self.logger.error("unable to parse init data")
|
||
|
|
return 1
|
||
|
|
self.sessions[session_id] = new_session
|
||
|
|
self.logger.info("session opened and init data parsed successfully")
|
||
|
|
return session_id
|
||
|
|
|
||
|
|
def _parse_init_data(self, init_data_b64):
|
||
|
|
parsed_init_data = wv_proto2.WidevineCencHeader()
|
||
|
|
try:
|
||
|
|
self.logger.debug("trying to parse init_data directly")
|
||
|
|
parsed_init_data.ParseFromString(base64.b64decode(init_data_b64)[32:])
|
||
|
|
except DecodeError:
|
||
|
|
self.logger.debug("unable to parse as-is, trying with removed pssh box header")
|
||
|
|
try:
|
||
|
|
id_bytes = parsed_init_data.ParseFromString(base64.b64decode(init_data_b64)[32:])
|
||
|
|
except DecodeError:
|
||
|
|
self.logger.error("unable to parse, unsupported init data format")
|
||
|
|
return None
|
||
|
|
self.logger.debug("init_data:")
|
||
|
|
for line in text_format.MessageToString(parsed_init_data).splitlines():
|
||
|
|
self.logger.debug(line)
|
||
|
|
return parsed_init_data
|
||
|
|
|
||
|
|
def close_session(self, session_id):
|
||
|
|
self.logger.debug("close_session(session_id={})".format(session_id))
|
||
|
|
self.logger.info("closing cdm session")
|
||
|
|
if session_id in self.sessions:
|
||
|
|
self.sessions.pop(session_id)
|
||
|
|
self.logger.info("cdm session closed")
|
||
|
|
return 0
|
||
|
|
else:
|
||
|
|
self.logger.info("session {} not found".format(session_id))
|
||
|
|
return 1
|
||
|
|
|
||
|
|
def set_service_certificate(self, session_id, cert_b64):
|
||
|
|
self.logger.debug("set_service_certificate(session_id={}, cert={})".format(session_id, cert_b64))
|
||
|
|
self.logger.info("setting service certificate")
|
||
|
|
|
||
|
|
if session_id not in self.sessions:
|
||
|
|
self.logger.error("session id doesn't exist")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
session = self.sessions[session_id]
|
||
|
|
|
||
|
|
message = wv_proto2.SignedMessage()
|
||
|
|
|
||
|
|
try:
|
||
|
|
message.ParseFromString(base64.b64decode(cert_b64))
|
||
|
|
except DecodeError:
|
||
|
|
self.logger.error("failed to parse cert as SignedMessage")
|
||
|
|
|
||
|
|
service_certificate = wv_proto2.SignedDeviceCertificate()
|
||
|
|
|
||
|
|
|
||
|
|
if message.Type:
|
||
|
|
self.logger.debug("service cert provided as signedmessage")
|
||
|
|
try:
|
||
|
|
service_certificate.ParseFromString(message.Msg)
|
||
|
|
|
||
|
|
except DecodeError:
|
||
|
|
self.logger.error("failed to parse service certificate")
|
||
|
|
return 1
|
||
|
|
else:
|
||
|
|
self.logger.debug("service cert provided as signeddevicecertificate")
|
||
|
|
try:
|
||
|
|
service_certificate.ParseFromString(base64.b64decode(cert_b64))
|
||
|
|
except DecodeError:
|
||
|
|
self.logger.error("failed to parse service certificate")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
self.logger.debug("service certificate:")
|
||
|
|
for line in text_format.MessageToString(service_certificate).splitlines():
|
||
|
|
self.logger.debug(line)
|
||
|
|
|
||
|
|
session.service_certificate = service_certificate
|
||
|
|
session.privacy_mode = True
|
||
|
|
|
||
|
|
return 0
|
||
|
|
|
||
|
|
def get_license_request(self, session_id):
|
||
|
|
self.logger.debug("get_license_request(session_id={})".format(session_id))
|
||
|
|
self.logger.info("getting license request")
|
||
|
|
|
||
|
|
if session_id not in self.sessions:
|
||
|
|
self.logger.error("session ID does not exist")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
session = self.sessions[session_id]
|
||
|
|
|
||
|
|
# raw pssh will be treated as bytes and not parsed
|
||
|
|
if self.raw_pssh:
|
||
|
|
license_request = wv_proto2.SignedLicenseRequestRaw()
|
||
|
|
else:
|
||
|
|
license_request = wv_proto2.SignedLicenseRequest()
|
||
|
|
client_id = wv_proto2.ClientIdentification()
|
||
|
|
|
||
|
|
if not os.path.exists(session.device_config.device_client_id_blob_filename):
|
||
|
|
self.logger.error("no client ID blob available for this device")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
with open(session.device_config.device_client_id_blob_filename, "rb") as f:
|
||
|
|
try:
|
||
|
|
cid_bytes = client_id.ParseFromString(f.read())
|
||
|
|
except DecodeError:
|
||
|
|
self.logger.error("client id failed to parse as protobuf")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
self.logger.debug("building license request")
|
||
|
|
if not self.raw_pssh:
|
||
|
|
license_request.Type = wv_proto2.SignedLicenseRequest.MessageType.Value('LICENSE_REQUEST')
|
||
|
|
license_request.Msg.ContentId.CencId.Pssh.CopyFrom(session.init_data)
|
||
|
|
else:
|
||
|
|
license_request.Type = wv_proto2.SignedLicenseRequestRaw.MessageType.Value('LICENSE_REQUEST')
|
||
|
|
license_request.Msg.ContentId.CencId.Pssh = session.init_data # bytes
|
||
|
|
|
||
|
|
if session.offline:
|
||
|
|
license_type = wv_proto2.LicenseType.Value('OFFLINE')
|
||
|
|
else:
|
||
|
|
license_type = wv_proto2.LicenseType.Value('DEFAULT')
|
||
|
|
license_request.Msg.ContentId.CencId.LicenseType = license_type
|
||
|
|
license_request.Msg.ContentId.CencId.RequestId = session_id
|
||
|
|
license_request.Msg.Type = wv_proto2.LicenseRequest.RequestType.Value('NEW')
|
||
|
|
license_request.Msg.RequestTime = int(time.time())
|
||
|
|
license_request.Msg.ProtocolVersion = wv_proto2.ProtocolVersion.Value('CURRENT')
|
||
|
|
if session.device_config.send_key_control_nonce:
|
||
|
|
license_request.Msg.KeyControlNonce = random.randrange(1, 2**31)
|
||
|
|
|
||
|
|
if session.privacy_mode:
|
||
|
|
if session.device_config.vmp:
|
||
|
|
self.logger.debug("vmp required, adding to client_id")
|
||
|
|
self.logger.debug("reading vmp hashes")
|
||
|
|
vmp_hashes = wv_proto2.FileHashes()
|
||
|
|
with open(session.device_config.device_vmp_blob_filename, "rb") as f:
|
||
|
|
try:
|
||
|
|
vmp_bytes = vmp_hashes.ParseFromString(f.read())
|
||
|
|
except DecodeError:
|
||
|
|
self.logger.error("vmp hashes failed to parse as protobuf")
|
||
|
|
return 1
|
||
|
|
client_id._FileHashes.CopyFrom(vmp_hashes)
|
||
|
|
self.logger.debug("privacy mode & service certificate loaded, encrypting client id")
|
||
|
|
self.logger.debug("unencrypted client id:")
|
||
|
|
for line in text_format.MessageToString(client_id).splitlines():
|
||
|
|
self.logger.debug(line)
|
||
|
|
cid_aes_key = get_random_bytes(16)
|
||
|
|
cid_iv = get_random_bytes(16)
|
||
|
|
|
||
|
|
cid_cipher = AES.new(cid_aes_key, AES.MODE_CBC, cid_iv)
|
||
|
|
|
||
|
|
encrypted_client_id = cid_cipher.encrypt(Padding.pad(client_id.SerializeToString(), 16))
|
||
|
|
|
||
|
|
service_public_key = RSA.importKey(session.service_certificate._DeviceCertificate.PublicKey)
|
||
|
|
|
||
|
|
service_cipher = PKCS1_OAEP.new(service_public_key)
|
||
|
|
|
||
|
|
encrypted_cid_key = service_cipher.encrypt(cid_aes_key)
|
||
|
|
|
||
|
|
encrypted_client_id_proto = wv_proto2.EncryptedClientIdentification()
|
||
|
|
|
||
|
|
encrypted_client_id_proto.ServiceId = session.service_certificate._DeviceCertificate.ServiceId
|
||
|
|
encrypted_client_id_proto.ServiceCertificateSerialNumber = session.service_certificate._DeviceCertificate.SerialNumber
|
||
|
|
encrypted_client_id_proto.EncryptedClientId = encrypted_client_id
|
||
|
|
encrypted_client_id_proto.EncryptedClientIdIv = cid_iv
|
||
|
|
encrypted_client_id_proto.EncryptedPrivacyKey = encrypted_cid_key
|
||
|
|
|
||
|
|
license_request.Msg.EncryptedClientId.CopyFrom(encrypted_client_id_proto)
|
||
|
|
else:
|
||
|
|
license_request.Msg.ClientId.CopyFrom(client_id)
|
||
|
|
|
||
|
|
if session.device_config.private_key_available:
|
||
|
|
key = RSA.importKey(open(session.device_config.device_private_key_filename).read())
|
||
|
|
session.device_key = key
|
||
|
|
else:
|
||
|
|
self.logger.error("need device private key, other methods unimplemented")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
self.logger.debug("signing license request")
|
||
|
|
|
||
|
|
hash = SHA1.new(license_request.Msg.SerializeToString())
|
||
|
|
signature = pss.new(key).sign(hash)
|
||
|
|
|
||
|
|
license_request.Signature = signature
|
||
|
|
|
||
|
|
session.license_request = license_request
|
||
|
|
|
||
|
|
self.logger.debug("license request:")
|
||
|
|
for line in text_format.MessageToString(session.license_request).splitlines():
|
||
|
|
self.logger.debug(line)
|
||
|
|
self.logger.info("license request created")
|
||
|
|
self.logger.debug("license request b64: {}".format(base64.b64encode(license_request.SerializeToString())))
|
||
|
|
return license_request.SerializeToString()
|
||
|
|
|
||
|
|
def provide_license(self, session_id, license_b64):
|
||
|
|
self.logger.debug("provide_license(session_id={}, license_b64={})".format(session_id, license_b64))
|
||
|
|
self.logger.info("decrypting provided license")
|
||
|
|
|
||
|
|
if session_id not in self.sessions:
|
||
|
|
self.logger.error("session does not exist")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
session = self.sessions[session_id]
|
||
|
|
|
||
|
|
if not session.license_request:
|
||
|
|
self.logger.error("generate a license request first!")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
license = wv_proto2.SignedLicense()
|
||
|
|
try:
|
||
|
|
license.ParseFromString(base64.b64decode(license_b64))
|
||
|
|
except DecodeError:
|
||
|
|
self.logger.error("unable to parse license - check protobufs")
|
||
|
|
return 1
|
||
|
|
|
||
|
|
session.license = license
|
||
|
|
|
||
|
|
self.logger.debug("license:")
|
||
|
|
for line in text_format.MessageToString(license).splitlines():
|
||
|
|
self.logger.debug(line)
|
||
|
|
|
||
|
|
self.logger.debug("deriving keys from session key")
|
||
|
|
|
||
|
|
oaep_cipher = PKCS1_OAEP.new(session.device_key)
|
||
|
|
|
||
|
|
session.session_key = oaep_cipher.decrypt(license.SessionKey)
|
||
|
|
|
||
|
|
lic_req_msg = session.license_request.Msg.SerializeToString()
|
||
|
|
|
||
|
|
enc_key_base = b"ENCRYPTION\000" + lic_req_msg + b"\0\0\0\x80"
|
||
|
|
auth_key_base = b"AUTHENTICATION\0" + lic_req_msg + b"\0\0\2\0"
|
||
|
|
|
||
|
|
enc_key = b"\x01" + enc_key_base
|
||
|
|
auth_key_1 = b"\x01" + auth_key_base
|
||
|
|
auth_key_2 = b"\x02" + auth_key_base
|
||
|
|
auth_key_3 = b"\x03" + auth_key_base
|
||
|
|
auth_key_4 = b"\x04" + auth_key_base
|
||
|
|
|
||
|
|
cmac_obj = CMAC.new(session.session_key, ciphermod=AES)
|
||
|
|
cmac_obj.update(enc_key)
|
||
|
|
|
||
|
|
enc_cmac_key = cmac_obj.digest()
|
||
|
|
|
||
|
|
cmac_obj = CMAC.new(session.session_key, ciphermod=AES)
|
||
|
|
cmac_obj.update(auth_key_1)
|
||
|
|
auth_cmac_key_1 = cmac_obj.digest()
|
||
|
|
|
||
|
|
cmac_obj = CMAC.new(session.session_key, ciphermod=AES)
|
||
|
|
cmac_obj.update(auth_key_2)
|
||
|
|
auth_cmac_key_2 = cmac_obj.digest()
|
||
|
|
|
||
|
|
cmac_obj = CMAC.new(session.session_key, ciphermod=AES)
|
||
|
|
cmac_obj.update(auth_key_3)
|
||
|
|
auth_cmac_key_3 = cmac_obj.digest()
|
||
|
|
|
||
|
|
cmac_obj = CMAC.new(session.session_key, ciphermod=AES)
|
||
|
|
cmac_obj.update(auth_key_4)
|
||
|
|
auth_cmac_key_4 = cmac_obj.digest()
|
||
|
|
|
||
|
|
auth_cmac_combined_1 = auth_cmac_key_1 + auth_cmac_key_2
|
||
|
|
auth_cmac_combined_2 = auth_cmac_key_3 + auth_cmac_key_4
|
||
|
|
|
||
|
|
session.derived_keys['enc'] = enc_cmac_key
|
||
|
|
session.derived_keys['auth_1'] = auth_cmac_combined_1
|
||
|
|
session.derived_keys['auth_2'] = auth_cmac_combined_2
|
||
|
|
|
||
|
|
self.logger.debug('verifying license signature')
|
||
|
|
|
||
|
|
lic_hmac = HMAC.new(session.derived_keys['auth_1'], digestmod=SHA256)
|
||
|
|
lic_hmac.update(license.Msg.SerializeToString())
|
||
|
|
|
||
|
|
self.logger.debug("calculated sig: {} actual sig: {}".format(lic_hmac.hexdigest(), binascii.hexlify(license.Signature)))
|
||
|
|
|
||
|
|
if lic_hmac.digest() != license.Signature:
|
||
|
|
self.logger.info("license signature doesn't match - writing bin so they can be debugged")
|
||
|
|
with open("original_lic.bin", "wb") as f:
|
||
|
|
f.write(base64.b64decode(license_b64))
|
||
|
|
with open("parsed_lic.bin", "wb") as f:
|
||
|
|
f.write(license.SerializeToString())
|
||
|
|
self.logger.info("continuing anyway")
|
||
|
|
|
||
|
|
self.logger.debug("key count: {}".format(len(license.Msg.Key)))
|
||
|
|
for key in license.Msg.Key:
|
||
|
|
if key.Id:
|
||
|
|
key_id = key.Id
|
||
|
|
else:
|
||
|
|
key_id = wv_proto2.License.KeyContainer.KeyType.Name(key.Type).encode('utf-8')
|
||
|
|
encrypted_key = key.Key
|
||
|
|
iv = key.Iv
|
||
|
|
type = wv_proto2.License.KeyContainer.KeyType.Name(key.Type)
|
||
|
|
|
||
|
|
cipher = AES.new(session.derived_keys['enc'], AES.MODE_CBC, iv=iv)
|
||
|
|
decrypted_key = cipher.decrypt(encrypted_key)
|
||
|
|
if type == "OPERATOR_SESSION":
|
||
|
|
permissions = []
|
||
|
|
perms = key._OperatorSessionKeyPermissions
|
||
|
|
for (descriptor, value) in perms.ListFields():
|
||
|
|
if value == 1:
|
||
|
|
permissions.append(descriptor.name)
|
||
|
|
print(permissions)
|
||
|
|
else:
|
||
|
|
permissions = []
|
||
|
|
session.keys.append(Key(key_id, type, Padding.unpad(decrypted_key, 16), permissions))
|
||
|
|
|
||
|
|
self.logger.info("decrypted all keys")
|
||
|
|
return 0
|
||
|
|
|
||
|
|
def get_keys(self, session_id):
|
||
|
|
if session_id in self.sessions:
|
||
|
|
return self.sessions[session_id].keys
|
||
|
|
else:
|
||
|
|
self.logger.error("session not found")
|
||
|
|
return 1
|