Re: [CFRG] Small subgroup question for draft-irtf-cfrg-hash-to-curve
Loup Vaillant-David <loup@loup-vaillant.fr> Fri, 09 April 2021 19:54 UTC
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From: Loup Vaillant-David <loup@loup-vaillant.fr>
To: Armando Faz <armfazh=40cloudflare.com@dmarc.ietf.org>, "Hao, Feng" <Feng.Hao@warwick.ac.uk>
Cc: IRTF CFRG <cfrg@irtf.org>
Date: Fri, 09 Apr 2021 21:54:44 +0200
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Subject: Re: [CFRG] Small subgroup question for draft-irtf-cfrg-hash-to-curve
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> The concern is akin to the generation of keys. For example, calling a > PRGN(seed) to get a key K. Of course, the key generation procedure > must ban the case of K=0. […] That is far from obvious to me. Banning a key just reduces the search space. Should we ban 0 because the attacker is more likely to test it first? Then what about 1? Or 37? Or 2^256 - 1? Any published number? In my opinion, the best solution is a uniform RNG. If we really want to maximise unpredictability, we must not ban any number. Not even zero. At least in the case of elliptic curves, one may argue that we should ban the identity point because its properties are observably different from all other points. Not just the bit pattern, but the fact that it has order 1. (And even then I'd be cautious.) Loup.
- [CFRG] Comment on draft-irtf-cfrg-hash-to-curve-10 Daira Hopwood
- Re: [CFRG] Comment on draft-irtf-cfrg-hash-to-cur… Daira Hopwood
- Re: [CFRG] Comment on draft-irtf-cfrg-hash-to-cur… Christopher Wood
- Re: [CFRG] Comment on draft-irtf-cfrg-hash-to-cur… Stanislav V. Smyshlyaev
- [CFRG] Small subgroup question for draft-irtf-cfr… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Loup Vaillant-David
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Russ Housley
- Re: [CFRG] Small subgroup question for draft-irtf… Richard Outerbridge
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Scott Fluhrer (sfluhrer)
- Re: [CFRG] Small subgroup question for draft-irtf… Scott Fluhrer (sfluhrer)
- Re: [CFRG] Small subgroup question for draft-irtf… Rene Struik
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Scott Fluhrer (sfluhrer)
- Re: [CFRG] Small subgroup question for draft-irtf… Armando Faz
- Re: [CFRG] Small subgroup question for draft-irtf… Loup Vaillant-David
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… rsw
- Re: [CFRG] Small subgroup question for draft-irtf… Björn Haase
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… rsw
- [CFRG] please use real names (was: Re: Small subg… Rene Struik
- Re: [CFRG] Small subgroup question for draft-irtf… Hugo Krawczyk
- Re: [CFRG] Small subgroup question for draft-irtf… Rene Struik
- Re: [CFRG] Small subgroup question for draft-irtf… Watson Ladd
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Rene Struik
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] Small subgroup question for draft-irtf… Watson Ladd
- Re: [CFRG] Small subgroup question for draft-irtf… rsw
- Re: [CFRG] Small subgroup question for draft-irtf… Loup Vaillant-David
- Re: [CFRG] Small subgroup question for draft-irtf… Riad S. Wahby
- Re: [CFRG] please use real names (was: Re: Small … Filippo Valsorda
- Re: [CFRG] please use real names (was: Re: Small … Scott Arciszewski
- Re: [CFRG] please use real names (was: Re: Small … Daniel Franke
- Re: [CFRG] please use real names (was: Re: Small … Watson Ladd
- Re: [CFRG] please use real names (was: Re: Small … Michael StJohns
- Re: [CFRG] please use real names (was: Re: Small … Henry de Valence
- Re: [CFRG] please use real names (was: Re: Small … Dan Harkins
- Re: [CFRG] Small subgroup question for draft-irtf… Hugo Krawczyk
- Re: [CFRG] please use real names (was: Re: Small … Peter Gutmann
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] please use real names (was: Re: Small … Squeamish Ossifrage
- Re: [CFRG] please use real names (was: Re: Small … Blumenthal, Uri - 0553 - MITLL
- Re: [CFRG] Small subgroup question for draft-irtf… Stanislav V. Smyshlyaev
- Re: [CFRG] Small subgroup question for draft-irtf… Björn Haase
- Re: [CFRG] please use real names (was: Re: Small … Soatok Dreamseeker
- Re: [CFRG] please use real names (was: Re: Small … Blumenthal, Uri - 0553 - MITLL
- Re: [CFRG] please use real names (was: Re: Small … Soatok Dreamseeker
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] please use real names (was: Re: Small … Daniel Franke
- Re: [CFRG] please use real names (was: Re: Small … Mike Hamburg
- Re: [CFRG] Small subgroup question for draft-irtf… Mike Hamburg
- Re: [CFRG] please use real names (was: Re: Small … Colin Perkins
- Re: [CFRG] please use real names (was: Re: Small … Blumenthal, Uri - 0553 - MITLL
- Re: [CFRG] please use real names (was: Re: Small … Soatok Dreamseeker
- Re: [CFRG] please use real names (was: Re: Small … Mike Hamburg
- Re: [CFRG] please use real names (was: Re: Small … Michael StJohns
- Re: [CFRG] Small subgroup question for draft-irtf… Hao, Feng
- Re: [CFRG] please use real names (was: Re: Small … Michael Sierchio
- [CFRG] Closure (was Re: Small subgroup question f… Hao, Feng
- Re: [CFRG] please use real names (was: Re: Small … Phillip Hallam-Baker
- Re: [CFRG] please use real names (was: Re: Small … Peter Gutmann
- Re: [CFRG] please use real names (was: Re: Small … David Jacobson
- Re: [CFRG] please use real names (was: Re: Small … Julia Hesse
- Re: [CFRG] Closure (was Re: Small subgroup questi… Armando Faz
- Re: [CFRG] Closure (was Re: Small subgroup questi… Hao, Feng
- Re: [CFRG] Closure (was Re: Small subgroup questi… Mike Hamburg
- Re: [CFRG] thoughts on clearing the cofactor in h… Loup Vaillant-David
- Re: [CFRG] Comment on draft-irtf-cfrg-hash-to-cur… Stanislav V. Smyshlyaev
- Re: [CFRG] Comment on draft-irtf-cfrg-hash-to-cur… Daira Hopwood
- Re: [CFRG] Comment on draft-irtf-cfrg-hash-to-cur… Riad S. Wahby
- [CFRG] (suggested language re mixing square roots… Rene Struik
- Re: [CFRG] Comment on draft-irtf-cfrg-hash-to-cur… Loup Vaillant-David
- Re: [CFRG] Comment on draft-irtf-cfrg-hash-to-cur… Daira Hopwood
- Re: [CFRG] (suggested language re mixing square r… Daira Hopwood
- Re: [CFRG] (suggested language re mixing square r… Rene Struik
- Re: [CFRG] please use real names (was: Re: Small … isis agora lovecruft