[louiskottmann]

This is a massive change for cache in webapp templates as it makes their rendering more stable and thus more cacheable.

A key component here is that we are trusting the user's browser to not be tampered with, as it is the browser that sets the Sec-Fetch-Site header and guarantees it has not been tampered with.

I wonder if that's a new thing ? Do we already rely on browsers being correct in their implementation for something equally fundamental ?

[tptacek]

The entire web security model assumes we can trust browsers to implement web security policies!

[louiskottmann]

I appreciate that, but in the case of TLS or CSRF tokens the server is not blindly trusting the browser in the way Sec-Fetch-Site makes it.

[tptacek]

Sure it is. The same-origin rule that holds the whole web security model together is entirely a property of browser behavior.

[louiskottmann]

That's indeed a good example of prior full trusting of the browser by the server.

[nchmy]

It's a shame you talked about browser tampering, since better caching is indeed a benefit of fetch metadata headers.