Re: The TCP and UDP checksum algorithm may soon need updating
Craig Partridge <craig@tereschau.net> Tue, 09 June 2020 19:32 UTC
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From: Craig Partridge <craig@tereschau.net>
Date: Tue, 9 Jun 2020 13:31:58 -0600
Message-ID: <CAHQj4CcRanB9c6_cEVcLgUNJBFMqXb_aH6eBBSaR0-_rQO5i9Q@mail.gmail.com>
Subject: Re: The TCP and UDP checksum algorithm may soon need updating
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Following up on notes from various folks, most notably John K. and Christian H., about checksums and encryption-based integrity protection, I wanted to make a couple of clarifying points. * If you are not worried about an adversary who seeks to alter your data in transit, then integrity protection is a lousy method for ensuring the received data is correct. The reality is that a checksum of width X bits can potentially catch 10x as many errors as an integrity check of X bits and will likely require 1/X computational power to compute. The requirement to make an integrity check proof against an adversary makes it less good. [Happy to explain more -- just trying to keep this note short]. * Some folks have assumed the TCP checksum, at 16 bits, misses an error about 1 in 2^16 times. That's not correct. There are classes of errors that TCP catches 100% of the time (e.g. single-bit errors). There are also classes of errors that the TCP checksum misses about 1 in 2^10 times. This latter is because the TCP checksum is not terribly good -- a better designed checksum would miss only about 1 in 2^16. Thanks! Craig -- ***** Craig Partridge's email account for professional society activities and mailing lists.
- The TCP and UDP checksum algorithm may soon need … Craig Partridge
- Re: The TCP and UDP checksum algorithm may soon n… Joe Touch
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Craig Partridge
- Re: The TCP and UDP checksum algorithm may soon n… Richard Barnes
- Re: The TCP and UDP checksum algorithm may soon n… Craig Partridge
- Re: The TCP and UDP checksum algorithm may soon n… Brian E Carpenter
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Richard Barnes
- Re: The TCP and UDP checksum algorithm may soon n… Richard Barnes
- Re: The TCP and UDP checksum algorithm may soon n… Christian Huitema
- Re: The TCP and UDP checksum algorithm may soon n… Christian Huitema
- Re: The TCP and UDP checksum algorithm may soon n… Phillip Hallam-Baker
- Re: The TCP and UDP checksum algorithm may soon n… Joseph Touch
- Re: The TCP and UDP checksum algorithm may soon n… Stewart Bryant
- Re: The TCP and UDP checksum algorithm may soon n… Phillip Hallam-Baker
- Re: The TCP and UDP checksum algorithm may soon n… Joseph Touch
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Michael Richardson
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Craig Partridge
- Re: The TCP and UDP checksum algorithm may soon n… Masataka Ohta
- Re: The TCP and UDP checksum algorithm may soon n… John Levine
- Re: The TCP and UDP checksum algorithm may soon n… Phillip Hallam-Baker
- Re: The TCP and UDP checksum algorithm may soon n… Joseph Touch
- Re: The TCP and UDP checksum algorithm may soon n… Christian Huitema
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Joseph Touch
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Salz, Rich
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Salz, Rich
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Michael Richardson
- Re: The TCP and UDP checksum algorithm may soon n… Benjamin Kaduk
- Re: The TCP and UDP checksum algorithm may soon n… Nick Hilliard
- Re: The TCP and UDP checksum algorithm may soon n… Carsten Bormann
- Re: The TCP and UDP checksum algorithm may soon n… Nick Hilliard
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Joe Touch
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Nick Hilliard
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Nick Hilliard
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Carsten Bormann
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… John C Klensin
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Richard Barnes
- Re: The TCP and UDP checksum algorithm may soon n… Russ Housley
- Re: The TCP and UDP checksum algorithm may soon n… Brian E Carpenter
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Warren Kumari
- Re: The TCP and UDP checksum algorithm may soon n… John C Klensin
- Re: The TCP and UDP checksum algorithm may soon n… Christian Huitema
- Re: The TCP and UDP checksum algorithm may soon n… John C Klensin
- Re: The TCP and UDP checksum algorithm may soon n… Craig Partridge
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Eric Rescorla
- Re: The TCP and UDP checksum algorithm may soon n… Craig Partridge
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Nico Williams
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… John Levine
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas
- Re: The TCP and UDP checksum algorithm may soon n… Brian E Carpenter
- Re: The TCP and UDP checksum algorithm may soon n… Warren Kumari
- Re: The TCP and UDP checksum algorithm may soon n… John R Levine
- Re: The TCP and UDP checksum algorithm may soon n… tom petch
- Re: The TCP and UDP checksum algorithm may soon n… Salz, Rich
- Re: The TCP and UDP checksum algorithm may soon n… Carsten Bormann
- Re: The TCP and UDP checksum algorithm may soon n… Salz, Rich
- Re: The TCP and UDP checksum algorithm may soon n… Craig Partridge
- Re: The TCP and UDP checksum algorithm may soon n… Michael Thomas