Adding public key to encrypted file

I am new to ABAP encryption and need some assistance. I have been trying to find a correct way to secure file before it is being sent to the recipient. I have used cl_hard_wired_encryptor to cipher my file but the only problem is that i do not know how to secure it using Public Key so that only those who have the key can access the file. Please correct me if this is not the way to go about this. I am willing to share my code which i used to encrypt file for farther corrections and assistance. Thank you guys