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crypto.py
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crypto.py
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from __future__ import annotations
from Cryptodome import Random
from librespot import util
import io
import re
import struct
import typing
if typing.TYPE_CHECKING:
from librespot.core import Session
class CipherPair:
__receive_cipher: Shannon
__receive_nonce = 0
__send_cipher: Shannon
__send_nonce = 0
def __init__(self, send_key: bytes, receive_key: bytes):
self.__send_cipher = Shannon()
self.__send_cipher.key(send_key)
self.__receive_cipher = Shannon()
self.__receive_cipher.key(receive_key)
def send_encoded(self, connection: Session.ConnectionHolder, cmd: bytes,
payload: bytes) -> None:
"""
Send decrypted data to the socket
:param connection:
:param cmd:
:param payload:
:return:
"""
self.__send_cipher.nonce(self.__send_nonce)
self.__send_nonce += 1
buffer = io.BytesIO()
buffer.write(cmd)
buffer.write(struct.pack(">H", len(payload)))
buffer.write(payload)
buffer.seek(0)
contents = self.__send_cipher.encrypt(buffer.read())
mac = self.__send_cipher.finish(4)
connection.write(contents)
connection.write(mac)
connection.flush()
def receive_encoded(self, connection: Session.ConnectionHolder) -> Packet:
"""
Receive and parse decrypted data from the socket
Args:
connection: ConnectionHolder
Return:
The parsed packet will be returned
"""
try:
self.__receive_cipher.nonce(self.__receive_nonce)
self.__receive_nonce += 1
header_bytes = self.__receive_cipher.decrypt(connection.read(3))
cmd = struct.pack(">s", bytes([header_bytes[0]]))
payload_length = (header_bytes[1] << 8) | (header_bytes[2] & 0xff)
payload_bytes = self.__receive_cipher.decrypt(
connection.read(payload_length))
mac = connection.read(4)
expected_mac = self.__receive_cipher.finish(4)
if mac != expected_mac:
raise RuntimeError()
return Packet(cmd, payload_bytes)
except IndexError:
raise RuntimeError("Failed to receive packet")
class DiffieHellman:
"""
DiffieHellman Keyexchange
"""
__prime = int.from_bytes(
b'\xff\xff\xff\xff\xff\xff\xff\xff\xc9\x0f'
b'\xda\xa2!h\xc24\xc4\xc6b\x8b\x80\xdc\x1c'
b'\xd1)\x02N\x08\x8ag\xcct\x02\x0b\xbe\xa6;'
b'\x13\x9b"QJ\x08y\x8e4\x04\xdd\xef\x95\x19'
b'\xb3\xcd:C\x1b0+\nm\xf2_\x147O\xe15mmQ\xc2'
b'E\xe4\x85\xb5vb^~\xc6\xf4LB\xe9\xa6:6 \xff'
b'\xff\xff\xff\xff\xff\xff\xff',
byteorder="big")
__private_key: int
__public_key: int
def __init__(self):
key_data = Random.get_random_bytes(0x5f)
self.__private_key = int.from_bytes(key_data, byteorder="big")
self.__public_key = pow(2, self.__private_key, self.__prime)
def compute_shared_key(self, remote_key_bytes: bytes):
"""
Compute shared_key
"""
remote_key = int.from_bytes(remote_key_bytes, "big")
return pow(remote_key, self.__private_key, self.__prime)
def private_key(self) -> int:
"""
Return DiffieHellman's private key
Returns:
DiffieHellman's private key
"""
return self.__private_key
def public_key(self) -> int:
"""
Return DiffieHellman's public key
Returns:
DiffieHellman's public key
"""
return self.__public_key
def public_key_bytes(self) -> bytes:
"""
Return DiffieHellman's packed public key
Returns:
DiffieHellman's packed public key
"""
return util.int_to_bytes(self.__public_key)
class Packet:
cmd: bytes
payload: bytes
def __init__(self, cmd: bytes, payload: bytes):
self.cmd = cmd
self.payload = payload
def is_cmd(self, cmd: bytes) -> bool:
return cmd == self.cmd
class Type:
secret_block = b"\x02"
ping = b"\x04"
stream_chunk = b"\x08"
stream_chunk_res = b"\x09"
channel_error = b"\x0a"
channel_abort = b"\x0b"
request_key = b"\x0c"
aes_key = b"\x0d"
aes_key_error = b"\x0e"
image = b"\x19"
country_code = b"\x1b"
pong = b"\x49"
pong_ack = b"\x4a"
pause = b"\x4b"
product_info = b"\x50"
legacy_welcome = b"\x69"
license_version = b"\x76"
login = b"\xab"
ap_welcome = b"\xac"
auth_failure = b"\xad"
mercury_req = b"\xb2"
mercury_sub = b"\xb3"
mercury_unsub = b"\xb4"
mercury_event = b"\xb5"
track_ended_time = b"\x82"
unknown_data_all_zeros = b"\x1f"
preferred_locale = b"\x74"
unknown_0x4f = b"\x4f"
unknown_0x0f = b"\x0f"
unknown_0x10 = b"\x10"
@staticmethod
def parse(val: typing.Union[bytes, None]) -> typing.Union[bytes, None]:
for cmd in [
Packet.Type.__dict__[attr] for attr in Packet.Type.__dict__
if re.search("__.+?__", attr) is None
and type(Packet.Type.__dict__[attr]) is bytes
]:
if cmd == val:
return cmd
return None
@staticmethod
def for_method(method: str) -> bytes:
if method == "SUB":
return Packet.Type.mercury_sub
if method == "UNSUB":
return Packet.Type.mercury_unsub
return Packet.Type.mercury_req
class Shannon:
n = 16
fold = n
initkonst = 0x6996c53a
keyp = 13
r: list
crc: list
init_r: list
konst: int
sbuf: int
mbuf: int
nbuf: int
def __init__(self):
self.r = [0 for _ in range(self.n)]
self.crc = [0 for _ in range(self.n)]
self.init_r = [0 for _ in range(self.n)]
def rotl(self, i: int, distance: int) -> int:
return ((i << distance) | (i >> (32 - distance))) & 0xffffffff
def sbox(self, i: int) -> int:
i ^= self.rotl(i, 5) | self.rotl(i, 7)
i ^= self.rotl(i, 19) | self.rotl(i, 22)
return i
def sbox2(self, i: int) -> int:
i ^= self.rotl(i, 7) | self.rotl(i, 22)
i ^= self.rotl(i, 5) | self.rotl(i, 19)
return i
def cycle(self) -> None:
t: int
t = self.r[12] ^ self.r[13] ^ self.konst
t = self.sbox(t) ^ self.rotl(self.r[0], 1)
for i in range(1, self.n):
self.r[i - 1] = self.r[i]
self.r[self.n - 1] = t
t = self.sbox2(self.r[2] ^ self.r[15])
self.r[0] ^= t
self.sbuf = t ^ self.r[8] ^ self.r[12]
def crc_func(self, i: int) -> None:
t: int
t = self.crc[0] ^ self.crc[2] ^ self.crc[15] ^ i
for j in range(1, self.n):
self.crc[j - 1] = self.crc[j]
self.crc[self.n - 1] = t
def mac_func(self, i: int) -> None:
self.crc_func(i)
self.r[self.keyp] ^= i
def init_state(self) -> None:
self.r[0] = 1
self.r[1] = 1
for i in range(2, self.n):
self.r[i] = self.r[i - 1] + self.r[i - 2]
self.konst = self.initkonst
def save_state(self) -> None:
for i in range(self.n):
self.init_r[i] = self.r[i]
def reload_state(self) -> None:
for i in range(self.n):
self.r[i] = self.init_r[i]
def gen_konst(self) -> None:
self.konst = self.r[0]
def add_key(self, k: int) -> None:
self.r[self.keyp] ^= k
def diffuse(self) -> None:
for _ in range(self.fold):
self.cycle()
def load_key(self, key: bytes) -> None:
i: int
j: int
t: int
padding_size = int((len(key) + 3) / 4) * 4 - len(key)
key = key + (b"\x00" * padding_size) + struct.pack("<I", len(key))
for i in range(0, len(key), 4):
self.r[self.keyp] = \
self.r[self.keyp] ^ \
struct.unpack("<I", key[i: i + 4])[0]
self.cycle()
for i in range(self.n):
self.crc[i] = self.r[i]
self.diffuse()
for i in range(self.n):
self.r[i] ^= self.crc[i]
def key(self, key: bytes) -> None:
self.init_state()
self.load_key(key)
self.gen_konst()
self.save_state()
self.nbuf = 0
def nonce(self, nonce: typing.Union[bytes, int]) -> None:
if type(nonce) is int:
nonce = bytes(struct.pack(">I", nonce))
self.reload_state()
self.konst = self.initkonst
self.load_key(nonce)
self.gen_konst()
self.nbuf = 0
def encrypt(self, buffer: bytes, n: int = None) -> bytes:
if n is None:
return self.encrypt(buffer, len(buffer))
buffer = bytearray(buffer)
i = 0
j: int
t: int
if self.nbuf != 0:
while self.nbuf != 0 and n != 0:
self.mbuf ^= (buffer[i] & 0xff) << (32 - self.nbuf)
buffer[i] ^= (self.sbuf >> (32 - self.nbuf)) & 0xff
i += 1
self.nbuf -= 8
n -= 1
if self.nbuf != 0:
return b""
self.mac_func(self.mbuf)
j = n & ~0x03
while i < j:
self.cycle()
t = ((buffer[i + 3] & 0xFF) << 24) | \
((buffer[i + 2] & 0xFF) << 16) | \
((buffer[i + 1] & 0xFF) << 8) | \
(buffer[i] & 0xFF)
self.mac_func(t)
t ^= self.sbuf
buffer[i + 3] = (t >> 24) & 0xFF
buffer[i + 2] = (t >> 16) & 0xFF
buffer[i + 1] = (t >> 8) & 0xFF
buffer[i] = t & 0xFF
i += 4
n &= 0x03
if n != 0:
self.cycle()
self.mbuf = 0
self.nbuf = 32
while self.nbuf != 0 and n != 0:
self.mbuf ^= (buffer[i] & 0xff) << (32 - self.nbuf)
buffer[i] ^= (self.sbuf >> (32 - self.nbuf)) & 0xff
i += 1
self.nbuf -= 8
n -= 1
return bytes(buffer)
def decrypt(self, buffer: bytes, n: int = None) -> bytes:
if n is None:
return self.decrypt(buffer, len(buffer))
buffer = bytearray(buffer)
i = 0
j: int
t: int
if self.nbuf != 0:
while self.nbuf != 0 and n != 0:
buffer[i] ^= (self.sbuf >> (32 - self.nbuf)) & 0xff
self.mbuf ^= (buffer[i] & 0xff) << (32 - self.nbuf)
i += 1
self.nbuf -= 8
n -= 1
if self.nbuf != 0:
return b""
self.mac_func(self.mbuf)
j = n & ~0x03
while i < j:
self.cycle()
t = ((buffer[i + 3] & 0xFF) << 24) | \
((buffer[i + 2] & 0xFF) << 16) | \
((buffer[i + 1] & 0xFF) << 8) | \
(buffer[i] & 0xFF)
t ^= self.sbuf
self.mac_func(t)
buffer[i + 3] = (t >> 24) & 0xFF
buffer[i + 2] = (t >> 16) & 0xFF
buffer[i + 1] = (t >> 8) & 0xFF
buffer[i] = t & 0xFF
i += 4
n &= 0x03
if n != 0:
self.cycle()
self.mbuf = 0
self.nbuf = 32
while self.nbuf != 0 and n != 0:
buffer[i] ^= (self.sbuf >> (32 - self.nbuf)) & 0xff
self.mbuf ^= (buffer[i] & 0xff) << (32 - self.nbuf)
i += 1
self.nbuf -= 8
n -= 1
return bytes(buffer)
def finish(self, n: int) -> bytes:
buffer = bytearray(4)
i = 0
j: int
if self.nbuf != 0:
self.mac_func(self.mbuf)
self.cycle()
self.add_key(self.initkonst ^ (self.nbuf << 3))
self.nbuf = 0
for j in range(self.n):
self.r[j] ^= self.crc[j]
self.diffuse()
while n > 0:
self.cycle()
if n >= 4:
buffer[i + 3] = (self.sbuf >> 24) & 0xff
buffer[i + 2] = (self.sbuf >> 16) & 0xff
buffer[i + 1] = (self.sbuf >> 8) & 0xff
buffer[i] = self.sbuf & 0xff
n -= 4
i += 4
else:
for j in range(n):
buffer[i + j] = (self.sbuf >> (i * 8)) & 0xff
break
return bytes(buffer)