Lets say for example I have to use a public online proxy like https://www.zend2.com
to to load a phpPHP webpage controlled by me containing sensitive data over httpsHTTPS.
How would iI make sure that the proxy in the middle doesn't have insight in the data (withoutwithout modifying the client (browser), js JavaScript and/or additional domain names &and servers only.
The solutionssolution's only goal is to prevent the public proxy attack layer. (theoretical).