def _decryptio_version1(total_head: bytes, io: IO,
encrypt_password: bytes) -> Optional[DecryptIO]:
encrypt_password = padding_key(encrypt_password, 32)
if len(total_head) < ENCRYPT_HEAD_LEN:
return
# Version 1
b_mc, magic_code, nonce_or_iv, total_origin_len = parse_head(total_head)
b_mc = aes256cbc_decrypt(b_mc, encrypt_password,
random_bytes(16, encrypt_password))
total_origin_len = u8x8_to_u64(total_origin_len)
if b_mc != BAIDUPCS_PY_CRYPTO_MAGIC_CODE:
return
if magic_code == SimpleEncryptIO.MAGIC_CODE:
return SimpleDecryptIO(io, encrypt_password, b"", total_origin_len)
elif magic_code == ChaCha20EncryptIO.MAGIC_CODE:
return ChaCha20DecryptIO(io, encrypt_password, nonce_or_iv,
total_origin_len)
elif magic_code == AES256CBCEncryptIO.MAGIC_CODE:
return AES256CBCDecryptIO(io, encrypt_password, nonce_or_iv,
total_origin_len)
else:
logging.warning(f"Unknown magic_code: {magic_code}")
return
def to_decryptio(io: IO, encrypt_key: Any):
if not encrypt_key:
return io
encrypt_key = padding_key(encrypt_key, 32)
head = io.read(ENCRYPT_HEAD_LEN)
if len(head) != ENCRYPT_HEAD_LEN:
io.seek(0, 0)
return io
b_mc, magic_code, nonce_or_iv, total_origin_len = parse_head(head)
b_mc = aes256cbc_decrypt(b_mc, encrypt_key, random_bytes(16, encrypt_key))
total_origin_len = u8x8_to_u64(total_origin_len)
if b_mc != BAIDUPCS_PY_CRYPTO_MAGIC_CODE:
io.seek(0, 0)
return io
if magic_code == SimpleEncryptIO.MAGIC_CODE:
return SimpleDecryptIO(io, encrypt_key, total_origin_len)
elif magic_code == ChaCha20EncryptIO.MAGIC_CODE:
return ChaCha20DecryptIO(io, encrypt_key, nonce_or_iv,
total_origin_len)
elif magic_code == AES256CBCEncryptIO.MAGIC_CODE:
return AES256CBCDecryptIO(io, encrypt_key, nonce_or_iv,
total_origin_len)
else:
logging.warning(f"Unknown magic_code: {magic_code}")
io.seek(0, 0)
return io
def _decryptio_version3(total_head: bytes, io: IO,
encrypt_password: bytes) -> Optional[DecryptIO]:
if len(total_head) < PADDED_ENCRYPT_HEAD_WITH_SALT_LEN:
return
enc_head, salt_for_head = (
total_head[:PADDED_ENCRYPT_HEAD_LEN],
total_head[PADDED_ENCRYPT_HEAD_LEN:],
)
encrypt_key_for_head, iv_for_head = generate_key_iv(
encrypt_password, salt_for_head, 32, 16)
head = aes256cbc_decrypt(enc_head, encrypt_key_for_head, iv_for_head)
b_mc, magic_code, padding_salt, total_origin_len = parse_head(head)
total_origin_len = u8x8_to_u64(total_origin_len)
salt = padding_salt[:8]
encrypt_key, nonce_or_iv = generate_key_iv(encrypt_password, salt, 32, 16)
if b_mc != BAIDUPCS_PY_CRYPTO_MAGIC_CODE:
return
eio = None
if magic_code == SimpleEncryptIO.MAGIC_CODE:
eio = SimpleDecryptIO(io, encrypt_key, nonce_or_iv, total_origin_len)
elif magic_code == ChaCha20EncryptIO.MAGIC_CODE:
eio = ChaCha20DecryptIO(io, encrypt_key, nonce_or_iv, total_origin_len)
elif magic_code == AES256CBCEncryptIO.MAGIC_CODE:
eio = AES256CBCDecryptIO(io, encrypt_key, nonce_or_iv,
total_origin_len)
else:
logging.warning(f"Unknown magic_code: {magic_code}")
return
eio._total_head_len = PADDED_ENCRYPT_HEAD_WITH_SALT_LEN
return eio