mirror of
https://github.com/malmeloo/FindMy.py.git
synced 2026-04-18 07:54:04 +02:00
72 lines
2.4 KiB
Python
72 lines
2.4 KiB
Python
"""Pure-python NIST P-224 Elliptic Curve cryptography. Used for some Apple algorithms."""
|
|
|
|
import hashlib
|
|
import hmac
|
|
|
|
from cryptography.hazmat.primitives import hashes, padding
|
|
from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
|
|
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
|
|
from cryptography.hazmat.primitives.kdf.x963kdf import X963KDF
|
|
|
|
P224_N = 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFF16A2E0B8F03E13DD29455C5C2A3D
|
|
|
|
|
|
def encrypt_password(password: str, salt: bytes, iterations: int) -> bytes:
|
|
"""Encrypt password using PBKDF2-HMAC."""
|
|
p = hashlib.sha256(password.encode("utf-8")).digest()
|
|
kdf = PBKDF2HMAC(
|
|
algorithm=hashes.SHA256(),
|
|
length=32,
|
|
salt=salt,
|
|
iterations=iterations,
|
|
)
|
|
return kdf.derive(p)
|
|
|
|
|
|
def decrypt_spd_aes_cbc(session_key: bytes, data: bytes) -> bytes:
|
|
"""Decrypt SPD data using SRP session key."""
|
|
extra_data_key = hmac.new(session_key, b"extra data key:", hashlib.sha256).digest()
|
|
extra_data_iv = hmac.new(session_key, b"extra data iv:", hashlib.sha256).digest()
|
|
# Get only the first 16 bytes of the iv
|
|
extra_data_iv = extra_data_iv[:16]
|
|
|
|
# Decrypt with AES CBC
|
|
cipher = Cipher(algorithms.AES(extra_data_key), modes.CBC(extra_data_iv))
|
|
decryptor = cipher.decryptor()
|
|
data = decryptor.update(data) + decryptor.finalize()
|
|
# Remove PKCS#7 padding
|
|
padder = padding.PKCS7(128).unpadder()
|
|
return padder.update(data) + padder.finalize()
|
|
|
|
|
|
def x963_kdf(value: bytes, si: bytes, length: int) -> bytes:
|
|
"""Single pass of X9.63 KDF with SHA1."""
|
|
return X963KDF(
|
|
algorithm=hashes.SHA256(),
|
|
sharedinfo=si,
|
|
length=length,
|
|
).derive(value)
|
|
|
|
|
|
def bytes_to_int(value: bytes) -> int:
|
|
"""Convert bytes in big-endian format to int."""
|
|
return int.from_bytes(value, "big")
|
|
|
|
|
|
def derive_ps_key(privkey: bytes, sk: bytes) -> bytes:
|
|
"""
|
|
Derive a primary or secondary key used by an accessory.
|
|
|
|
:param privkey: Private key generated during pairing
|
|
:param sk: Current secret key for this time period.
|
|
Use SKN to derive the primary key, SKS for secondary.
|
|
"""
|
|
priv_int = bytes_to_int(privkey)
|
|
|
|
at = x963_kdf(sk, b"diversify", 72)
|
|
u = bytes_to_int(at[:36]) % (P224_N - 1) + 1
|
|
v = bytes_to_int(at[36:]) % (P224_N - 1) + 1
|
|
|
|
key = (u * priv_int + v) % P224_N
|
|
return key.to_bytes(28, "big")
|