How to encrypt a text file downloaded from AL11 tcode

Hi Gurus,

I have a requirement to download a file(may be a .txt format) into presentation server from AL11 t-code(Application server).

The file will have some confidential bank details,so the customer needs the file should be in encrypted format and write protected while downloaded from AL11 tcode.

How can I achieve the encryption and write protected?

Thanks & Regards

Ayyappan.V