[TLS] Re: ECH Proxy Mode

[Raghu Saxena <[e-mail]>]

Hi,

On 9/3/24 10:52 PM, 涛叔 wrote:
> This idea was derived from my attempt to implement encrypted TLS SNI Proxy. The SNI
> does not only expose privacy information, many ISP use it to block certain web site.
> Even though the current draft of ECH works to protect the ClientHello, it can only
> protect the sites that deployed the ECH.
>
> If we can adjust the current design and let the client-facing generate and response
> the accept_confirmation signal, we can make ECH everywhere without upgrading any of
> current TLS backend server. Which means the client-facing can work as an encrypted
> TLS SNI Proxy.

I'm trying to understand what exactly your use-case here is. Wouldn't a 
naive HTTPS Proxy w/ CONNECT be sufficient?

E.g. if we have the proxy domain `https://myproxy.com` , and the website 
we want to connect to is `https://supersecret.com`, then assuming a 
classic HTTPS Proxy running on `myproxy.com`, the Client would make a 
TLS handshake to `myproxy.com` and reveal the Proxy SNI, however once 
the TLS handshake with the proxy is complete, the `CONNECT` to 
`supersecret.com` will be inside the TLS tunnel, so it will be private.

I think this would be sufficient, since even in the split-example with 
ECH you mention, the `public_name` of the first client-facing server 
will be visible anyway.

Regards,

Raghu Saxena