TLS and Request Confidentiality

This document describes how to accomplish confidentiality of EWP HTTP requests with the use of TLS transport.

• What is the status of this document?
• See the index of all other EWP Specifications

Introduction

This is a pretty standard method of achieving HTTP request confidentiality. It simply requires TLS (HTTPS) to be used. Is assumes that such requests cannot be overheard, and it doesn't apply any additional request body encryption.

Implementing a server

You MUST acquire a CA-signed certificate for your domain(s), and install it on your servers. These are just the "regular" domain-validated certificates. You MUST serve your endpoint(s) via HTTPS.

Implementing a client

Not much more to describe here. You simply MUST make your requests via HTTPS protocol.

Security considerations

When not to use this method

In case of the server:

• If the request MAY contain private user data, and you don't trust your own internal network (the one between your actual server and your TLS terminator), then you MUST NOT include <tls/> in your <request-encryption-methods>.

In case of the client:

• If the request MAY contain private user data, and you cannot be sure that your root/intermediate CA certificate store has not been tampered with, then you MUST NOT use this method.

Main security questions

The Authentication and Security document requires each request encryption method to explicitly answer a couple of questions:

How the client's request must look like? How can the server detect that the client is using this particular method of encryption?

The client simply makes its request via HTTPS. It the request doesn't include any other indication that the client is using some other method, then the server may assume it's using this one.

How the server publishes his encryption key? How the client retrieves it securely?

The client uses HTTPS server certificate validation to make sure that it is communicating with the proper party. It receives all required encryption keys during the TLS handshake and trusts root CAs for the security of this exchange.

Note, that this only works when the clients can trust their CA certificate stores. See When not to use this method chapter above.

How to encrypt and decrypt the request? Which parts are covered by the encryption and which are not?

HTTPS does that on its own. All parts of the request are covered, including all headers, and the request target (URL's path).