[openssl-dev] [openssl.org #4271] Enhancement Request: Support TCP Fast Open

[Viktor Dukhovni]

On Mon, Jan 25, 2016 at 06:42:02PM +0000, Kurt Roeckx via RT wrote:

> On Mon, Jan 25, 2016 at 06:24:55PM +0000, Sara Dickinson via RT wrote:
> > Hi,
> > 
> > I would like to request that support be added to OpenSSL to enable client applications to make use use of TCP Fast Open (https://tools.ietf.org/html/rfc7413 <https://tools.ietf.org/html/rfc7413>) when initiating the TLS handshake on Linux (TCP Fast Open is available in Linux kernel > 4.1). 
> 
> I've seen that request, and I have tought about it.  I'm just
> wondering if that comes with security consequences, like replay
> attacks.  Specially in combination with what they're doing with
> TLS 1.3.
> 
> The API clearly doesn't support anything like that currently.

No security impact.  Just a saving of 1-RTT on "warm" TCP reconnects.

If the client's first flight payload also carries 0-RTT TLS 1.3
data, the exposure is the same whether TCP fast open is used or
not.

-- 
	Viktor.