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Re: [TLS] Should we require compressed points

Andrei Popov <Andrei.Popov@microsoft.com> Wed, 22 October 2014 19:39 UTC

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From: Andrei Popov <Andrei.Popov@microsoft.com>
To: Martin Thomson <martin.thomson@gmail.com>, Eric Rescorla <ekr@rtfm.com>
Thread-Topic: [TLS] Should we require compressed points
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Date: Wed, 22 Oct 2014 19:39:25 +0000
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Cc: "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Should we require compressed points
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I'm not convinced that a requirement to support multiple point compression algorithms helps eliminate complexity:).

Point compression does help save a bit of space, so that we can carry more of those lovely human-readable ALPN IDs. I agree that point compression may be a valuable feature.

While I would prefer to keep uncompressed points, this would not be a deal-breaker for me. Losing support for renegotiation concerns me much more.

Cheers,

Andrei

-----Original Message-----
From: Martin Thomson [mailto:martin.thomson@gmail.com] 
Sent: Wednesday, October 22, 2014 11:47 AM
To: Eric Rescorla
Cc: Andrei Popov; tls@ietf.org
Subject: Re: [TLS] Should we require compressed points

On 22 October 2014 11:26, Eric Rescorla <ekr@rtfm.com> wrote:
>> What are the reasons for getting rid of uncompressed points?
>
>
> Really what I want is to get rid of point negotiation, because it's 
> yet another point of complexity and it's not universally implemented 
> anyway. Given that people seem to think that compressed points are 
> better, I figured that was the way to go. If people prefer to just 
> require uncompressed points (at least for the existing X9.63 curves) I 
> could certainly live with that.

Yep, and I'll note that 32 octets isn't a trivial amount of space in a handshake.  We're particularly space constrained here.  If that's 32 octets more of application data I'd have available, I suspect that another compressed HTTP/2 request - or a good proportion of one - could fit in that space (for a 0 RTT mode in particular).

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