I have to transfer some sensitive information over a JavaScript AJAX Call, over an unencrypted channel (HTTP, not HTTPS).
I'd like to encrypt the data, but encryption on the JavaScript side means I expose the key, which makes symmetric encryption only an exercise in security by obscurity.
Is there any asymmetric encryption for JavaScript? That way, I can keep the Server decryption key secret. (I'm not worried about the security of Server > JavaScript messages, only about the security of a certain JavaScript > Server message)
Best Answer
The reason why you need encryption at all is probably to protect against a man-in-the-middle. There are scenarios where an attacker is able to sniff at the traffic without being able to change it. This solution would protect against that threat, but it would provide no protection at all against a man-in-the-middle that is able to modify the traffic.
If the attacker can change the traffic, then he will also be able to change the script that does the encryption. The easiest attack would be to just remove the encryption completely from the script. If you don't have https, and a man-in-the-middle is possible (which is the case in almost every scenario) then you don't have any control at all over the html or javascript that is presented to the end user. The attacker may rewrite your html code and javascript completely, disablign encryption, creating new form fields in your form etc. Https is a prerequisite for secure communication in the web-channel.