I am using smtp for sending the email and attachments from my system. What I want to accomplish is that I should be able to send information in an encrypted form so that the message cannot be tempered. I am using https for sending the emails. But is there any way I can encrypt the emails and attachments with AES or SHA1 and the reciever that is recieving that email can decrypt it. For example I send an encrypted email at gmail or any mail server. The user can decrypt the email.
Thanks in advance.