I wanted to create file encryption and decrption application

Question

Hello Team,

I had asked by my faculty to create a application which in use to encrypt and decrypt a file.

Requirement is like:

User1 will select a file which he need to encrypt.
After encryption he will send file to user2 by any way.
 
User2 can only view this file in that application only ,.
File Type : .csv

Please help me out.