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

Nick Hilliard <> Mon, 08 June 2020 17:24 UTC

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Subject: Re: The TCP and UDP checksum algorithm may soon need updating
To: Michael Thomas <>
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From: Nick Hilliard <>
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Date: Mon, 8 Jun 2020 18:24:07 +0100
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Michael Thomas wrote on 08/06/2020 17:59:
> On 6/8/20 2:09 AM, Nick Hilliard wrote:
>> in their current incarnations, transport mode ipsec and tcp-ao aren't 
>> deployable at scale in the same way that tls is.
> why would you say that? what layer the crypto is performed seems sort of 
> irrelevant: rsa, aes and sha don't care who calls them. i assume that 
> you can hack ipsec to emulate clients not having certs. what's left?

Usability?  How about you put someone's granny in front of a computer 
and give her the simple task of transferring some data over tls, or 
tcp-ao, or ipsec.  Any data would do, e.g a http GET, or a one-line 
message to her grand-daughter to say happy birthday.

>> Regarding transport layer integrity, there are distant echoes of the 
>> old circuit-switched vs packet-switched arguments going on here. 
>> tcp/ip made circuit switching redundant by loosening its assumptions 
>> about transport layer reliability.  I wonder are we now seeing 
>> something similar with TLS, which no longer depends on either 
>> underlying transport or ip header integrity by pushing data stream 
>> integrity management higher up the stack.
> Quic seems to have done the opposite by moving it down. But do I trust 
> higher levels to deal with congestion avoidance correctly? Not at all. 
> That's a tragedy of the commons waiting to melt down.

The other aspect of these distant echoes related to how previous 
incumbencies gave pretty serious push-back due to their concerns about 
people not paying enough attention to lower-layer considerations.