[PATCH 1 of 2] SSL: Encrypted Client Hello (ECH) support

[Maxim Dounin]

Hello!

On Tue, Sep 09, 2025 at 12:55:56PM +0100, Stephen Farrell wrote:

> Great to see that. I'll give it a try in a day or two (travelling
> at the moment). One initial question: the configuration directive
> you added differs fron what we suggested for nginx and apache (we
> suggested a directive names a directory of ECH PEM files), so I'm
> wondering if there was a specific reason to take that approach?

I personally don't think that a directory with files is a great 
approach to managing keys, and rather prefer explicit 
specification of which files to use as keys instead.  In 
particular, this approach makes it easier to check files provided 
and complain if there are any issues, such as accidental 
corruption.  It also makes it possible to easily specify which 
key(s) should be used for retries (currently the first one 
specified; can be extended to an explicit flag if more than one 
retry key will be needed).

Also, I don't think that more than 3 keys are actually needed 
here, even considering automatic rotation (that is, current key, 
next key, and previous key), and a directory for just 3 keys looks 
like an overkill to me.

Last but not least, the approach with explicitly specified keys is 
in line with what [free]nginx already uses for TLS session ticket 
keys (http://freenginx.org/r/ssl_session_ticket_key).  Using the 
same approach for Encrypted Client Hello keys is quite natural.

I believe I've previously suggested to use this approach during 
early review of your ECH patches.

[...]

-- 
Maxim Dounin
http://mdounin.ru/