Re: The TCP and UDP checksum algorithm may soon need updating

Brian E Carpenter <> Mon, 08 June 2020 20:57 UTC

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Subject: Re: The TCP and UDP checksum algorithm may soon need updating
To: Nico Williams <>, Michael Thomas <>
Cc: "" <>
References: <> <> <> <> <> <> <> <> <> <> <20200608190220.GA18021@localhost>
From: Brian E Carpenter <>
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Date: Tue, 9 Jun 2020 08:57:00 +1200
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On 09-Jun-20 07:02, Nico Williams wrote:
> On Mon, Jun 08, 2020 at 11:23:09AM -0700, Michael Thomas wrote:
>> ssl had the advantage that it 1) beat ipsec to market, and 2) wasn't subject
>> to API differences from OS layer calls like IPsec was, and with quite a bit
>> of churn as i recall too. it's really too bad, imo. we wouldn't have had to
>> do the contortions of dtls, for example. and now there's this problem. none
>> of them are earth shattering, but it would have been cleaner.
> You can sprinkle TLS anywhere you have an octet stream.  You can
> sprinkle DTLS anywhere you have datagram flows. 

Unless someone says "multicast". 


> No need for OS support
> -- it will just work.  IPsec?  IPsec requires OS support.
> Also, IPsec got a lot of things wrong.  It's simply not usable at
> Internet scale as originally intended because... it's IP-layer, so it
> deals in discrete packets and IP addresses.  Well, discrete packets do
> not define application connections/sessions[*], IP addresses are too
> dynamic and useless for authentication and authorization[**], and
> configuration is ETOOHARD.
> As you can see, a dozen years ago was already too late, but our idea
> then was to
>  - construct protection guarantees for packet flows using IPsec,
>  - to use anonymous or anonymous-like key exchanges to key IPsec,
>  - and to use channel binding from application layer protocols that can
>    authenticate more useful names than IP addresses.
> Nico
> [*] In the IPsec architecture, RFC 4301, there is no guarantee that the
>     packets making up a TCP connection, say, will have anything like
>     similar protection for the lifetime of the TCP connection.
>     Everything about how a TCP conenction is protected by IPsec depends
>     entirely on *configuration* with no standard interfaces _at all_ for
>     applications to manipulate said configuration.
> [**] Yes, in RFC 4301 you're supposed to specify things like trust
>      anchors and policies like "any peer with a certificate from this CA
>      can _claim_ IP addresses in the following prefixes/ranges".  This
>      _cannot_ scale to Internet scale.
>      Giving up on authentication and authorization in the RFC 4301
>      scheme (BTNS, RFC 5387) and constructing logical packet flows with
>      consistent protection during their lifetimes (RFC 5660), fixes the
>      problem.  It didn't get implemented -- even if it had been, TLS was
>      already king.  This would all have to have happened at least half a
>      decade earlier, if not a whole decade earlier, to have had a
>      chance.
>      What was particularly appealing at one point was the possibility of
>      having ESP offload in NIC HW.  The lower in the stack the crypto
>      happens, the easier it is to offload it.