How can you do pre-processing if you are not allowed to have access to plaintext data? SyferText can help you! With SyferText, you can define pre-processing components to perform pre-processing remotely, blindly and in a completely secure fashion.
Encrypted Training of Deep Learning models with PyTorch + PySyft on MNIST
Encrypted Deep Learning Classification with PyTorch & PySyft in < 33ms on MNIST