Re: [Cfrg] Requesting removal of CFRG co-chair
"Dan Harkins" <dharkins@lounge.org> Sat, 04 January 2014 08:24 UTC
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Date: Sat, 04 Jan 2014 00:24:15 -0800
From: Dan Harkins <dharkins@lounge.org>
To: Trevor Perrin <trevp@trevp.net>
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Cc: David McGrew <mcgrew@cisco.com>, "cfrg@irtf.org" <cfrg@irtf.org>
Subject: Re: [Cfrg] Requesting removal of CFRG co-chair
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Trevor, On Fri, December 27, 2013 7:56 am, Trevor Perrin wrote: > I'm still not sure what you're asking. Let's just look at a crude > analysis of the "40-loops" countermeasure Kevin endorsed, comparing > CFRG draft-00 vs draft-01/draft-02. > > Let's assume that modular square roots are calculated via modular > exponentiation, and that Legendre symbol calculations take less time. > Let's also ignore the variable time taken by a Legendre symbol > calculation and other conditional logic, and just count the number of > ops. > > In draft-00, the hunt-and-peck loop in 3.2.1 performs Legendre symbol > calculations until it finds a square (probability ~1/2), at which > point a square root is performed. So: > - 1 modular exponentiation > - Variable number of Legendre symbol calculations > - geometric distribution with mean ~2, variance ~2 > > In draft-01 and draft-02, the hunt-and-peck loop continues until it > completes 40 loops, with a probability ~1/2 of performing a modular > exponentiation on each iteration. So: > - Variable number of modular exponentiations > - binomial distribution with mean ~20, variance ~10 > - 40 Legendre symbol calculations > > The 40-loops algorithm was intended to reduce timing variance but > instead increases it, and increases computation cost as well. So I > think "ineffective" is a fair description. Do you agree? That is a good description of a problem. I now see how poor the text is that describes the hunting-and-pecking loop. I wish you would have put it in the form of a constructive comment, or at least separated this signal from the general noise of your posts. But nevertheless, I see that that section is poorly worded, I understand your comment, and will address it in a subsequent version of the draft. A sincere thank you for this comment! Dan.
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- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Eggert, Lars
- Re: [Cfrg] Requesting removal of CFRG co-chair Alyssa Rowan
- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
- Re: [Cfrg] Requesting removal of CFRG co-chair Trevor Perrin
- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
- Re: [Cfrg] Requesting removal of CFRG co-chair Trevor Perrin
- Re: [Cfrg] Requesting removal of CFRG co-chair Watson Ladd
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- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
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- Re: [Cfrg] Requesting removal of CFRG co-chair Paul Lambert
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- Re: [Cfrg] Requesting removal of CFRG co-chair Watson Ladd
- Re: [Cfrg] Requesting removal of CFRG co-chair Alyssa Rowan
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
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- Re: [Cfrg] Requesting removal of CFRG co-chair Mike Simpson
- Re: [Cfrg] Requesting removal of CFRG co-chair Watson Ladd
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Alyssa Rowan
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Robert Ransom
- Re: [Cfrg] Requesting removal of CFRG co-chair Adam Back
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair Yoav Nir
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- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
- Re: [Cfrg] Requesting removal of CFRG co-chair William Whyte
- Re: [Cfrg] Requesting removal of CFRG co-chair Henrick Hellström
- Re: [Cfrg] Requesting removal of CFRG co-chair Alyssa Rowan
- Re: [Cfrg] Requesting removal of CFRG co-chair John Viega
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
- Re: [Cfrg] Requesting removal of CFRG co-chair Richard Barnes
- Re: [Cfrg] Requesting removal of CFRG co-chair John Bradley
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- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair Richard Barnes
- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
- Re: [Cfrg] Requesting removal of CFRG co-chair Trevor Perrin
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
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- Re: [Cfrg] Requesting removal of CFRG co-chair John Viega
- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
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- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
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- Re: [Cfrg] Requesting removal of CFRG co-chair David McGrew
- Re: [Cfrg] Requesting removal of CFRG co-chair David McGrew
- Re: [Cfrg] Requesting removal of CFRG co-chair David McGrew
- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair David McGrew
- Re: [Cfrg] Requesting removal of CFRG co-chair Brian Weis
- Re: [Cfrg] Requesting removal of CFRG co-chair Tom Ritter
- Re: [Cfrg] Requesting removal of CFRG co-chair Brian Weis
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] CFRG and thwarting pervasive montoring Paul Lambert
- Re: [Cfrg] Requesting removal of CFRG co-chair Henrick Hellström
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Yoav Nir
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Alyssa Rowan
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair Yoav Nir
- Re: [Cfrg] Requesting removal of CFRG co-chair David McGrew
- Re: [Cfrg] Requesting removal of CFRG co-chair Alyssa Rowan
- Re: [Cfrg] Requesting removal of CFRG co-chair Trevor Perrin
- Re: [Cfrg] Requesting removal of CFRG co-chair Nikos Mavrogiannopoulos
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Watson Ladd
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Yoav Nir
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair Robert Ransom
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
- Re: [Cfrg] Requesting removal of CFRG co-chair Yoav Nir
- Re: [Cfrg] Requesting removal of CFRG co-chair Paul Hoffman
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- Re: [Cfrg] Requesting removal of CFRG co-chair Eggert, Lars
- Re: [Cfrg] Requesting removal of CFRG co-chair idontneedcoffee
- Re: [Cfrg] Requesting removal of CFRG co-chair Stephen Farrell
- Re: [Cfrg] Requesting removal of CFRG co-chair Tao Effect
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- Re: [Cfrg] CFRG and thwarting pervasive montoring Watson Ladd
- Re: [Cfrg] CFRG and thwarting pervasive montoring Paul Hoffman
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- Re: [Cfrg] misuse-resistant AEAD (was: Re: CFRG a… Watson Ladd
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- Re: [Cfrg] Requesting removal of CFRG co-chair David McGrew
- Re: [Cfrg] misuse-resistant AEAD (was: Re: CFRG a… Dan Harkins
- Re: [Cfrg] misuse-resistant AEAD (was: Re: CFRG a… Watson Ladd
- Re: [Cfrg] misuse-resistant AEAD (was: Re: CFRG a… Dan Harkins
- Re: [Cfrg] misuse-resistant AEAD David McGrew
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- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] Requesting removal of CFRG co-chair Dan Harkins
- Re: [Cfrg] changes to hunt-and-peck algorithm (Re… Trevor Perrin
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- Re: [Cfrg] Requesting removal of CFRG co-chair Daniel Kahn Gillmor