File Encryption

Question

Hello,.

My faculty had asked me to submit a project on File Encrypting .

Scenario is Like;

User1 will encrypt excel file using app and sebd to user 2 via any mode.

User2 can view this encrypted file via application only , he cant decrypt or save that file.

I have no idea about it .

Please help me out with this.

A develop application will be much help full for me so that i can understand and re develop accordingly.