opscrypto.py decryptfile doesn't work

```
% ../oppo_decrypt/opscrypto.py decryptfile lemonadep_22_O.05_210324.ops
Oneplus CryptTools V1.4 (c) B. Kerler 2019-2021
----------------------------

Extracting lemonadep_22_O.05_210324.ops.dec
```

top shows 100% CPU usage for this process,
`lemonadep_22_O.05_210324.ops.dec` is not appeared even in `/proc`

`decrypt` works fine with this file