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Re: [Cfrg] Schnorr just as vulnerable to bad RNG

Rene Struik <rstruik.ext@gmail.com> Fri, 25 July 2014 14:16 UTC

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Date: Fri, 25 Jul 2014 10:15:49 -0400
From: Rene Struik <rstruik.ext@gmail.com>
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To: Bodo Moeller <bmoeller@acm.org>
References: <20140725131738.6639765.60290.17138@certicom.com> <CADMpkcJD_qXkNFECQ4YoBUhyxQJNrh1=K6gAGfJ23jFWaD51-Q@mail.gmail.com>
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Subject: Re: [Cfrg] Schnorr just as vulnerable to bad RNG
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RFC 6979 - Deterministic Usage of the Digital Signature Algorithm (DSA) 
and Elliptic Curve Digital Signature Algorithm (ECDSA) (August 2013)

On 7/25/2014 10:09 AM, Bodo Moeller wrote:
> Dan Brown <dbrown@certicom.com <mailto:dbrown@certicom.com>>:
>
>     Some people propose using deriving the ephemerals from the message
>     and a long term key. This does not seem any better as an algorithm
>     than the DRBG approach, provided the X9.62 algorithm is adhered to.
>
>     There's an RFC melding both these ideas, but that is trying fix
>     something that is not broken, at the algorithm level.
>
>
> It's certainly not broken, but more fragile than necessary. If you use 
> an appropriate PRNG with proper seeding, there's no problem, but in 
> practice, sometimes you *think* you have proper seeding when you 
> actually don't.  That's usually bad in any case, but it can be less 
> bad with the hash-based approach.  Since the additional cost of 
> hashing is minor, I think hashing is a good idea for implementations.
>
> (What document are you referring to?  Really an RFC?)
>
> Bodo
>
>
>
>
>
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